Shell and tube evaporators considered as the main heat exchange equipment.
Shell and tube evaporator
Shell and tube evaporator designed to cool the fresh water circulating in the system. Heat from the water pipes passed the boiling water in evaporator. The evaporator can be used to cool other fluids in agreement with the manufacturer. The surface of the shell and tube evaporator is treated by specially designed heat isolating compound, for more efficient operation.
Shell and tube evaporators considered as the main heat exchange equipment.
Shell and tube evaporators considered as the main heat exchange equipment.
How do ASME specification numbers for different materials and alloys differ from those given by the ASTM?
What role do the ASTM Standards play in specifying the materials?
ASTM has various committees that evaluate the materials based upon the wide experiences the committee members have. They also give a specific number to the material.
How do ASME specification numbers for different materials and alloys differ from those given by the ASTM?
ASME prefixes an S, e.g., SA202. It generally indicates that the material A202 specified by the ASTM has been adopted by the ASME Code, although it may not be true in all cases. Not all ASTM specified materials adopted by the ASME Code.
Types of Hot Water Systems
The basic setup of a solar hot water system includes:
- solar collectors;
- storage tank;
- various control devices;
- network of piping.
Indirect heating systems circulate water or fluid through a continuous pipe loop and transfer heat via a heat exchanger.
Direct heating systems run fresh water through the collector’s piping and into the home for direct use.
Hot water heating systems can be also defined by their means of circulation:
1. Active heating systems use an electric pump to move the water or fluid mechanically.
2. Passive heating systems move water without the use of pumps. As the water in the collector heats up, it rises up into a storage tank while cold water refills the collector tubes.
Solar heating systems for domestic heating needs may include a separate storage tank that feeds preheated water into a standard tank-style hot water heater or a tankless on-demand water heater. That way it’s easier to boost the temperature of the water for use, as needed. In other systems, solar-heated water is fed directly into a single hot water tank, which typically contains its own conventional heat source.
- solar collectors;
- storage tank;
- various control devices;
- network of piping.
Indirect heating systems circulate water or fluid through a continuous pipe loop and transfer heat via a heat exchanger.
Direct heating systems run fresh water through the collector’s piping and into the home for direct use.
Hot water heating systems can be also defined by their means of circulation:
1. Active heating systems use an electric pump to move the water or fluid mechanically.
2. Passive heating systems move water without the use of pumps. As the water in the collector heats up, it rises up into a storage tank while cold water refills the collector tubes.
Solar heating systems for domestic heating needs may include a separate storage tank that feeds preheated water into a standard tank-style hot water heater or a tankless on-demand water heater. That way it’s easier to boost the temperature of the water for use, as needed. In other systems, solar-heated water is fed directly into a single hot water tank, which typically contains its own conventional heat source.
Florida Solar Energy Center
The FSEC is the Florida state energy research institute. Among its roles in the solar industry, the FSEC conducts tests to compare efficiency and economics of flat plate collectors. The FSEC website (http://www.fsec.ucf.edu/) provides a list of tested products by manufacturer, as well as numerous educational tools for consumers thinking about going solar.
Solar Hot Water Heating Systems
In a basic solar hot water heating system, water or antifreeze fluid is circulating through rooftop solar collectors, then down into the house or swimming pool, where it feed a system to supply domestic hot water or to supplement space heating equipment.
Solar hot water heating systems are used in many different climates and are inexpensive and reliable. In addition to environmental benefits, solar hot water heating systems can yield quick financial returns.
Most of the times, solar heating systems are used in conjunction with conventional heating equipment, such as a hot water heater or boiler, providing preheated water to the system to reduce its net energy use.
On average, solar heating systems for domestic heating needs are most cost effective when they supply around 70 percent of home’s hot water.
Solar heating systems supplementing heating equipment are most cost-effective when designed to offset 40 to 80 percent of the home’s annual demand.
Solar hot water heating systems are used in many different climates and are inexpensive and reliable. In addition to environmental benefits, solar hot water heating systems can yield quick financial returns.
Most of the times, solar heating systems are used in conjunction with conventional heating equipment, such as a hot water heater or boiler, providing preheated water to the system to reduce its net energy use.
On average, solar heating systems for domestic heating needs are most cost effective when they supply around 70 percent of home’s hot water.
Solar heating systems supplementing heating equipment are most cost-effective when designed to offset 40 to 80 percent of the home’s annual demand.
How to install tankless water heater?
1. Attach the mounting hardware to the framing members as recommended. Make sure the unit will be level and positioned so the tankless water heater will meet minimum clearance requirement.
2. Set the tankless water heater onto the mounting hardware. Run code-approved vent pipe from unit out of the house. Follow local code regarding length of the vent and placement of the termination.
3. Attach the exhaust connector and gasket at the exhaust condensate tube or trap in the exhaust line of required by code.
4. Run gas supply line from the main and connect to the tankless water heater unit as directed. Pipe material and size must meet minimum standards for the unit. Flexible copper lines generally are not allowed. Black iron pipes are preferred for natural gas. While installing tankless water heater, make sure that line is equipped with a manual shutoff valve near the heater unit.
5. Run cold water supply to the water inlet port on the tankless water heater unit and connect as directed. Insert an inlet filter screen between the supply line and the inlet port.
6. Connect a pressure relief valve (PRV) to the hot supply line; confirm that any shutoff valves located downstream from the pressure relief valves. Connect the hot water outlet to the correct outlet port with a compression fitting. Attach a discharge line to the pressure relief valve if required by code.
7. Follow manufacturer’s instructions to make the electrical connections to operate the blower fan and control panel. Most tankless water heater units must be independently grounded. Replace cover plate when finished. Tankless water heater must pass the inspection before use. This typically includes leak and pressure inspections on the gas and water lines. Replace cover plate when finished.
8. Test the gas line for leaks by brushing soap suds onto the connections. Leaking gas will cause the suds to bubble up. Follow the manufacturer’s instructions for setting up, operating, and maintaining your tankless water heater unit.
2. Set the tankless water heater onto the mounting hardware. Run code-approved vent pipe from unit out of the house. Follow local code regarding length of the vent and placement of the termination.
3. Attach the exhaust connector and gasket at the exhaust condensate tube or trap in the exhaust line of required by code.
4. Run gas supply line from the main and connect to the tankless water heater unit as directed. Pipe material and size must meet minimum standards for the unit. Flexible copper lines generally are not allowed. Black iron pipes are preferred for natural gas. While installing tankless water heater, make sure that line is equipped with a manual shutoff valve near the heater unit.
5. Run cold water supply to the water inlet port on the tankless water heater unit and connect as directed. Insert an inlet filter screen between the supply line and the inlet port.
6. Connect a pressure relief valve (PRV) to the hot supply line; confirm that any shutoff valves located downstream from the pressure relief valves. Connect the hot water outlet to the correct outlet port with a compression fitting. Attach a discharge line to the pressure relief valve if required by code.
7. Follow manufacturer’s instructions to make the electrical connections to operate the blower fan and control panel. Most tankless water heater units must be independently grounded. Replace cover plate when finished. Tankless water heater must pass the inspection before use. This typically includes leak and pressure inspections on the gas and water lines. Replace cover plate when finished.
8. Test the gas line for leaks by brushing soap suds onto the connections. Leaking gas will cause the suds to bubble up. Follow the manufacturer’s instructions for setting up, operating, and maintaining your tankless water heater unit.
Ways to heat your home with wood
Heating home with outside wood furnace is especially beneficial to people suffering from asthma and other respiratory diseases, as outside wood furnace burns wood away from the home, thus eliminating smoke and ashes inside the house.
If you live in a suburb, smoke from outside wood furnace may disturb the neighbors, if chimney is low. This is not a problem for rural areas.
Tankless Water Heaters Advantages
Tankless water heaters can be fueled by natural gas or propane. The operating principle of tankless water heaters is quite simple: cold water enters the tankless water heater and flows through the coils, exiting the heater at temperatures of 100-140 degree F.
A moderate size tankless water heater can deliver 6-8 gallons of heated water per minute. This is enough to supply a shower and 1-2 sink faucets.
Tankless water heaters with higher output rates, such as 10 gallons per minute, are able to supply multiple bathrooms that are used concurrently with heated hot water.
There are always other options available, such as to install multiple tankless water heaters to supply various zones of your home with hot water.
Gas tankless water heaters must be independently vented out of the house with gas rated vent pipe. In many cases, tankless water heaters should be installed with twin-pipe vent system, where fresh air is piped directly into a sealed burner from outdoors.
From cost-of-operation and efficiency standpoint, installing gas-fueled tankless water heaters makes a lot of sense. But installing tankless water heaters yourself is extremely challenging and dangerous task. A permit and on-site inspection are required.
Which types of water heaters qualify for tax credit?
There are currently three types of water heaters that qualify for the tax credit for energy-efficiency:
- Whole house tankless water heaters;
- Solar water heaters;
- Electric heat pump water heaters.
To qualify for the tax credit water heater must have:
- Energy Star designation;
- Manufacturer Certification Statement.
FAQ – Do any high-efficiency gas storage water heaters qualify for the tax credit?
A – No. Only tankless water heaters, solar, and electric heat pump types qualify for the tax credit for energy-efficiency.
FAQ – Do small tankless water heaters qualify for the tax credit?
A – No. The minimum approved flow is 2.5 GPM over a 77 degree rise.
FAQ – If I install the water heater myself, can I add the cost of my labor to the total price for calculating the tax credit amount?
A – No, but check http://www.energystar.gov/ before filling out your tax return to make sure the rule hasn’t changed.
- Whole house tankless water heaters;
- Solar water heaters;
- Electric heat pump water heaters.
To qualify for the tax credit water heater must have:
- Energy Star designation;
- Manufacturer Certification Statement.
Water Heater FAQs:
FAQ – Do any high-efficiency gas storage water heaters qualify for the tax credit?
A – No. Only tankless water heaters, solar, and electric heat pump types qualify for the tax credit for energy-efficiency.
FAQ – Do small tankless water heaters qualify for the tax credit?
A – No. The minimum approved flow is 2.5 GPM over a 77 degree rise.
FAQ – If I install the water heater myself, can I add the cost of my labor to the total price for calculating the tax credit amount?
A – No, but check http://www.energystar.gov/ before filling out your tax return to make sure the rule hasn’t changed.
How to choose Water Heaters to get Tax Credit?
In an average household, hot water costs accounts roughly at 15 cents out of every dollar paid for utility bills. However, much of this money actually spent for just keeping the water in the storage tank hot. Conventional hot water heaters are relatively inexpensive, but high utility bills will eat up that initial savings within first few years.
Conventional Water Heaters are simply large steel tank wrapped with a thin layer of insulation. In conventional water heaters, water is warmed by a gas or electric heating element that kicks on whenever the water temperature drops below the specified settings.
High-efficiency Water Heaters have basic design similar to conventional water heaters, but use better burners, power venting, and have more insulation to achieve lower energy usage. Many high-efficiency water heaters received the Energy Star designation, but almost none of them are efficient enough to qualify for energy-efficiency tax credit.
Gas-condensing Water Heaters also do not qualify yet for energy-efficiency tax credit.
Solar Hot Water Heaters store water like conventional water heaters do, but the energy used for hot water heating comes from solar collectors. Typically solar hot water heaters use a backup heat source for cloudy days. Solar hot water heaters with energy star label qualify for energy-efficiency tax credit.
Electric Heat Pump Water Heaters are relatively a new technology. They work like air source heat pumps, extracting heat from air with a liquid refrigerant and then passing the heated refrigerant through coils in the hot water heater, where the heat is transferred to the water.
What is a thermal plate in brazed plate heat exchanger?
Thermal plate is the one that transfers heat. In brazed plate heat exchangers and PHEs, the end plates do not transfer any heat. End plates in brazed plate heat exchangers and PHEs simply contain the fluid and prevent it from touching the pressure plates, which are generally made of mild steel and mot not suitable for a particular fluid.
Thus, in a brazed plate heat exchanger and PHE with a total of 40 plates, only 38 plates are thermal plates, regardless of the number of passes.
However, if one connector plate is used in between the plate pack, so that on fluid exchangers heat with two others, the plates on either side of the connector plate also do not transfer any heat, and out of total of 20 plates, only 16 will be thermal plates.
Thus, in a brazed plate heat exchanger and PHE with a total of 40 plates, only 38 plates are thermal plates, regardless of the number of passes.
However, if one connector plate is used in between the plate pack, so that on fluid exchangers heat with two others, the plates on either side of the connector plate also do not transfer any heat, and out of total of 20 plates, only 16 will be thermal plates.
What are the different ways of fabricating a product from pieces?
There are different ways of fabricating a product from pieces, such as:
- Mechanical joining – using rivets, bolts and nuts, screws, or interlocking joints
- Welding – metallurgical bond by applying heat or pressure
- Brazing and soldering – metallurgical bond by inserting a metal having a lower melting point than the parts
- Adhesive bonding – using adhesives or resins
- Mechanical joining – using rivets, bolts and nuts, screws, or interlocking joints
- Welding – metallurgical bond by applying heat or pressure
- Brazing and soldering – metallurgical bond by inserting a metal having a lower melting point than the parts
- Adhesive bonding – using adhesives or resins
Electric Radiant Heating Systems
Any electrical conductor that offers resistance to the flow of electricity generates a certain amount of heat. That amount of heat is in direct proportion to the degree of resistance. This method of generating heat is employed in radiant floor heating systems.
The conductor typically used in radiant heating systems is an electric heating cable embedded in the floors, walls, or ceilings. Those electric cables can be installed at the site (as it is the case with a new construction), or may come in the form of prewired, factory-assembled, panel-type units. The heat generated by the cables is transferred to the occupants and surfaces in the room by low-intensity radiation.
Site installed heating cables or prewired and assembled panel units are used in the following types of radiant heating systems:
- radiant ceiling panel systems;
- radiant wall panel systems;
- radiant floor panel systems.
The conductor typically used in radiant heating systems is an electric heating cable embedded in the floors, walls, or ceilings. Those electric cables can be installed at the site (as it is the case with a new construction), or may come in the form of prewired, factory-assembled, panel-type units. The heat generated by the cables is transferred to the occupants and surfaces in the room by low-intensity radiation.
Site installed heating cables or prewired and assembled panel units are used in the following types of radiant heating systems:
- radiant ceiling panel systems;
- radiant wall panel systems;
- radiant floor panel systems.
Advantages of Electric Heating and Cooling
Among the principal advantages of using electric heating and cooling systems are:
• greater safety
• quiet operation
• economy of space
• reduction of drafts
• reduction of outside noise
• uniform temperature
• structural design flexibility
Although the chances of an explosion in gas- or oil-fired heating systems have become very small because of the safety features built into these systems, an explosion simply cannot occur in electric heating system.
A properly installed electric heating and cooling system will last for years without any problems. If a problem occurs, resistance builds up in the line to the fuse or circuit breaker box. At certain point, the fuse will blow or the circuit breaker will trip, which will automatically shut off the electricity before any damage occurs.
Electric heating units are very compact and therefore utilize very little space. In baseboard systems, there is no need for ducts or pipes to carry a heat medium from its source to the space being heated. These factors offer a great degree of structural design flexibility because duct and pipe arrangements do not have to be taken into consideration. In addition, no chimney or flue arrangement is necessary.
If a structure is properly insulated for electric heating and cooling, there is a noticeable reduction of drafts and the degree of outside noise penetration. Moreover, uniform temperatures will prevail.
Finally, an electric heating system is generally quieter than other types because fewer mechanical parts involved in the electric system design. Quiet operation is particularly a characteristic of baseboard-type installations.
• greater safety
• quiet operation
• economy of space
• reduction of drafts
• reduction of outside noise
• uniform temperature
• structural design flexibility
Although the chances of an explosion in gas- or oil-fired heating systems have become very small because of the safety features built into these systems, an explosion simply cannot occur in electric heating system.
A properly installed electric heating and cooling system will last for years without any problems. If a problem occurs, resistance builds up in the line to the fuse or circuit breaker box. At certain point, the fuse will blow or the circuit breaker will trip, which will automatically shut off the electricity before any damage occurs.
Electric heating units are very compact and therefore utilize very little space. In baseboard systems, there is no need for ducts or pipes to carry a heat medium from its source to the space being heated. These factors offer a great degree of structural design flexibility because duct and pipe arrangements do not have to be taken into consideration. In addition, no chimney or flue arrangement is necessary.
If a structure is properly insulated for electric heating and cooling, there is a noticeable reduction of drafts and the degree of outside noise penetration. Moreover, uniform temperatures will prevail.
Finally, an electric heating system is generally quieter than other types because fewer mechanical parts involved in the electric system design. Quiet operation is particularly a characteristic of baseboard-type installations.
What is the difference between low-carbon steel and high-carbon steel?
Low-carbon steel has ≤0.2 percent carbon, can be easily welded, but cannot be hardened.
High-carbon steel has 0.7-2 percent carbon, can be hardened, but cannot be easily welded. Welding results in a change in the structure of the material and redistribution of the carbon and thus affects the strength of steel adversely.
High-carbon steel has 0.7-2 percent carbon, can be hardened, but cannot be easily welded. Welding results in a change in the structure of the material and redistribution of the carbon and thus affects the strength of steel adversely.
Disadvantages of Electric Heating and Cooling Systems
An electrically heated and cooled structure offers certain disadvantages when compared with other types of heating and cooling systems. When choosing an energy source for heating and cooling system, it is always necessary to weight the advantages and disadvantages of the system and its energy source carefully against the requirements you demand from them.
An electrically heated or cooled structure must be well insulated against heat gain or loss. If it isn’t, the cost of heating or cooling can be extremely high. For that reason, electric systems are rarely installed in existing structures, except in situations where a room is added or a basement is finished.
Electric heating and cooling systems generally have higher operating costs. These energy costs depend on the insulation type of the structure, orientation of the building, the total number of windows (total glass area), the cost of electricity where the structure is located, and the energy use habits of the occupants.
Another disadvantage of electric furnaces is that they are frequently oversized. An oversized electric furnace heats up and cools down too rapidly to maintain acceptable comfort levels in the rooms of the building. However, oversizing is not a problem limited to electric furnaces.
An electrically heated or cooled structure must be well insulated against heat gain or loss. If it isn’t, the cost of heating or cooling can be extremely high. For that reason, electric systems are rarely installed in existing structures, except in situations where a room is added or a basement is finished.
Electric heating and cooling systems generally have higher operating costs. These energy costs depend on the insulation type of the structure, orientation of the building, the total number of windows (total glass area), the cost of electricity where the structure is located, and the energy use habits of the occupants.
Another disadvantage of electric furnaces is that they are frequently oversized. An oversized electric furnace heats up and cools down too rapidly to maintain acceptable comfort levels in the rooms of the building. However, oversizing is not a problem limited to electric furnaces.
Infiltration Heat Loss
During the heating season, a portion of heat loss is attributed to the infiltration of cooler outside air into the interior of the structure through cracks around doors and windows and other openings. The amount of air entering the structure by infiltration is important in estimating the requirements of the heating system, as well as composition of the air.
A pound of air is composed both from dry air and moisture particles, which are combined so that each one retains individual characteristics. The distinction of these two basic components of air is important, because each involved with a different type of heat; dry air with specific heat, and moisture content with latent heat.
Each heating system must be designed with the capability of warming the cooler infiltrated dry air to the temperature of the air inside the structure. This amount of heat referred to as sensible heat loss and is expressed in Btu/hr.
The most common methods of calculating heat loss by infiltration are:
1) the crack method;
2) the air-change method.
A pound of air is composed both from dry air and moisture particles, which are combined so that each one retains individual characteristics. The distinction of these two basic components of air is important, because each involved with a different type of heat; dry air with specific heat, and moisture content with latent heat.
Each heating system must be designed with the capability of warming the cooler infiltrated dry air to the temperature of the air inside the structure. This amount of heat referred to as sensible heat loss and is expressed in Btu/hr.
The most common methods of calculating heat loss by infiltration are:
1) the crack method;
2) the air-change method.
Calculating Heat Loss in Slab Construction
The heat loss for residential and small commercial buildings constructed on a concrete slab at or near grade level is computed on the basis of heat loss per foot of exposed edge.
For example, a concrete slab 20 ft x 25 ft would have an exposed edge of 90 ft (on a perimeter of the exposed edge of a concrete slab). The heat loss depends on the thickness of insulation along the exposed edge of the concrete slab and the outside design temperature range. This information can be obtained from ASHRAE publications.
To calculate a heat loss in Btu/hr, simply multiply the total length of the exposed edge by the heat loss in Btu/hr per lineal foot (lin ft).
Heat loss of a concrete slab = length of the exposed edge x heat loss per lineal foot
For example, a 90 ft exposed edge with 2-in-edge insulation at n outdoor design temperature of 35 degrees F can be calculated as follows:
90 lin ft x 45 Btu/hr/lin ft = 4,050 Btu/hr
For example, a concrete slab 20 ft x 25 ft would have an exposed edge of 90 ft (on a perimeter of the exposed edge of a concrete slab). The heat loss depends on the thickness of insulation along the exposed edge of the concrete slab and the outside design temperature range. This information can be obtained from ASHRAE publications.
To calculate a heat loss in Btu/hr, simply multiply the total length of the exposed edge by the heat loss in Btu/hr per lineal foot (lin ft).
Heat loss of a concrete slab = length of the exposed edge x heat loss per lineal foot
For example, a 90 ft exposed edge with 2-in-edge insulation at n outdoor design temperature of 35 degrees F can be calculated as follows:
90 lin ft x 45 Btu/hr/lin ft = 4,050 Btu/hr
Calculating Heat Loss in Basement
Heat loss in basement depends on many different variables. One of them ground temperature, which functions as outdoor design temperature in the heat loss transmission formula. The ground temperatures vary by geographical location.
The usual method for calculating heat loss transmission through basement walls is to view them as being divided into 2 (two) sections. The upper section extends from the frost line to the basement ceiling and includes portions of the wall that are exposed to outdoor air temperatures. The heat loss for the upper section is calculated the same way that other surfaces exposed to the outside temperature are calculated.
The lower section, the wall extending from the frost line to the basement floor and the floor itself can be calculated on the basis of the ground temperature. The ground temperature is substituted for the outside design temperature when calculating heat loss.
The usual method for calculating heat loss transmission through basement walls is to view them as being divided into 2 (two) sections. The upper section extends from the frost line to the basement ceiling and includes portions of the wall that are exposed to outdoor air temperatures. The heat loss for the upper section is calculated the same way that other surfaces exposed to the outside temperature are calculated.
The lower section, the wall extending from the frost line to the basement floor and the floor itself can be calculated on the basis of the ground temperature. The ground temperature is substituted for the outside design temperature when calculating heat loss.
Calculating Heat Loss for a Door
It’s not easy to calculate the coefficient of heat transmission (U-value) for a door, because doors vary by size, thickness, and materials.
A fairly accurate rule-of-thumb method of calculating heat loss is to use the U-value for a comparable size single-pane glass window.
If you wish to compute the coefficient of heat transmission for a door, the necessary data can be found in ASHRAE publications. The same source can be used for calculating the coefficient of heat transmission of windows.
A fairly accurate rule-of-thumb method of calculating heat loss is to use the U-value for a comparable size single-pane glass window.
If you wish to compute the coefficient of heat transmission for a door, the necessary data can be found in ASHRAE publications. The same source can be used for calculating the coefficient of heat transmission of windows.
Snow melt and retention devices
Snow retention systems on the roof just needed to spring compressed snow and ice blocks are uniformly melted and descended from the roof, scratching her and threatening the inhabitants of the house. Snow retention protects the eaves and gutters of the truncation of the weight of ice blocks.
Snow retention - is an artificial process that protects the roof from scratches and prevents rainwater from gutters to tearing because of the snow weight. Snow retention for roofing, as well as heating of the roof, ensure the safety of residential homes, as a necessary element for the design of its insurance. Modern models of snow melt and snow retention:
Lattice snow melt or retention devices set for high roofs of urban buildings, as well as the tiled roofs of private houses. Thus, the detention occurs even small pieces of ice. Snow retention is due to the lattice, which is attached to the edge of the roof. Such snow melt or retention devices mounted with universal supports.
Plastic snow melt or retention devices made of the same material as the usual metal. They are inexpensive, but reliable, used on slopes with an inclination of 30 degrees.
Snow retention - is an artificial process that protects the roof from scratches and prevents rainwater from gutters to tearing because of the snow weight. Snow retention for roofing, as well as heating of the roof, ensure the safety of residential homes, as a necessary element for the design of its insurance. Modern models of snow melt and snow retention:
- Tubular
- Lattice
- point
- Plate
Lattice snow melt or retention devices set for high roofs of urban buildings, as well as the tiled roofs of private houses. Thus, the detention occurs even small pieces of ice. Snow retention is due to the lattice, which is attached to the edge of the roof. Such snow melt or retention devices mounted with universal supports.
Plastic snow melt or retention devices made of the same material as the usual metal. They are inexpensive, but reliable, used on slopes with an inclination of 30 degrees.
Brazing of flat plate heat exchanger
Brazing is well-suited to making leak-tight tubing joints like this because once everything gets hot enough the filler metal (the thin rod) melts it runs all the way around the joint.
Heating pipes - a necessary decision.
Heated pipe - a system which includes the heating part (heating cable and accessories), distribution and information network (special cables, junction boxes, fasteners), a control system (control cabinet, temperature controllers, sensors for cable heating systems, etc. etc.).Heating cables, through which water is heated - is the main element of the heating system that provides the reliability and efficiency. Cable heating plumbing and piping needed for many reasons:
- there is no destruction of water after freezing;
- constant temperature of hot water;
- heating gutters - getting rid of stagnation on the roof of melt water;
- stops the formation of condensation on the surface of the pipe.
Heated water pipes can be carried out both inside and outside the structure. It is also possible industrial heating piping, which occurs when self-regulatory means of a heating cable. These same elements are used performing heating tanks and vessels.
Why and how roof heating works?
Also, when heating cables roof is not delayed in the water on the roof in the autumn-spring period, shall not be harmful mechanical cleaning of the roof. Thus, a safe anti-icing for roofs. Heating systems that share a roof on:
• System heating cables;
• hydrophobic de-icing compositions.
The heating system is a roof heating cable eliminates the formation of ice dams and smooth performance drain in the autumn and winter. Heating of the roof is provided with special seals heating cable that is laid in the ground water accumulation. Cable changing power depending on temperature prevents the formation of ice coatings of different origin.
Heating is unnecessary on sunny days and should be done once the temperature falls to frosting degrees, so the heating system should be equipped with temperature control. Heating cables are installed in the way of water, which is formed from melting ice. De-icing for the roof should be divided into sections when it comes to complex systems.
Hydrophobic de-icing for the roof involves the installation of the composition, which does not prevent the formation of ice, and helps him run off quickly. De-icing for the roof - is anti-corrosive, environmentally friendly, and water-proofing.
Electric Cable Heating for steps, stairs, ramps, outdoor areas, lawns and loading platforms:
Cable heating for steps, stairs, ramps, outdoor areas, lawns and loading platforms:
Heating systems are applicable in open areas, anywhere you want to keep clear of snow and ice: steps, stairs, ramps, and entrances to the garages, lawns, loading platforms. Pure ice and snow, stairs, walkways - is security, and excellent appearance of your home, office, construction site.
Heating pads provide safe pedestrian walking in the cold season. Heating stages frees people from strewing the snow or ice, salt, chipping ice, etc. Heating protects against injury in freezing temperatures.
These tasks are performed by a special system of Anti-ice for the open areas of land. The main task of the heating system is to prevent freezing in sub-zero temperatures.
Heating ramps and other areas is usually done with a heating cable, and special heating mats. They represent the heating section, which is assembled with shielded twisted pair cable with heating properties. Heating pads used almost everywhere:
* In private homes, in country houses and sites;
* Stores and hypermarkets;
* Office buildings, etc.
Effective heating ramps achieved thanks to a special cable that fits into the soil under the sand or gravel, withstanding load transport. The advantage of de-icing system for open areas are:
1. Big time savings on manual labor to clear the land of ice or snow;
2. Heating ramps, stairs and other areas extends the road and pavement surface;
3. Such a heating system fairly easily installed under a different cover: granite, ceramics, concrete, stone, etc.
Energy savings for heating pads provide thermostats. It is worth noting that one of the heating elements can be implemented simultaneously heating steps and the nearest sites.
Heating pads provide safe pedestrian walking in the cold season. Heating stages frees people from strewing the snow or ice, salt, chipping ice, etc. Heating protects against injury in freezing temperatures.
These tasks are performed by a special system of Anti-ice for the open areas of land. The main task of the heating system is to prevent freezing in sub-zero temperatures.
Heating ramps and other areas is usually done with a heating cable, and special heating mats. They represent the heating section, which is assembled with shielded twisted pair cable with heating properties. Heating pads used almost everywhere:
* In private homes, in country houses and sites;
* Stores and hypermarkets;
* Office buildings, etc.
Effective heating ramps achieved thanks to a special cable that fits into the soil under the sand or gravel, withstanding load transport. The advantage of de-icing system for open areas are:
1. Big time savings on manual labor to clear the land of ice or snow;
2. Heating ramps, stairs and other areas extends the road and pavement surface;
3. Such a heating system fairly easily installed under a different cover: granite, ceramics, concrete, stone, etc.
Energy savings for heating pads provide thermostats. It is worth noting that one of the heating elements can be implemented simultaneously heating steps and the nearest sites.
Cable heating in agriculture? Is it really needed?
The use of cable systems for these purposes can increase profitability, to extend the harvest season.
The use of cable systems for space heating in greenhouses, winter gardens, for heating the soil in greenhouses, seedbed, the beds will give you the opportunity to get great results and a rich harvest. You'll get the extension of the fruiting season, accelerate the growth of cultures in greenhouses, accelerate the germination of seeds. Heating cable enables you to grow heat-loving plants, native to the country are tropical and subtropical climate latitudes.
Conservatory and a greenhouse - these are special structures that are designed to grow vegetables, flowers, fruits and other plants in any season. Each of them need a special electrical heating system.
Heating of greenhouses and other buildings can get excellent results:
• Heated greenhouses promotes effective acceleration of growth of plants;
• Heated greenhouses can extend the season to collect the necessary crop;
• Heated greenhouses helps to grow exotic and heat-loving plants.
Heating conservatories, greenhouses, and cold framesis usually done by cable heating systems. Electric heating systems consists of electric heating heating cables with some power. This heating cable provides the necessary temperature for plants growing in greenhouses. Special cable provides heating the soil to the required temperature. This is all done as follows:
1. A specific layer of soil is taken off;
2. Then it is replased by special foundation of sand;
3. Insulating coating laid out;
4. Heating cable laid throughout the buildings, so that heating of greenhouses is the most effective;
5. all this layer of loose soil and watered with water.
Also, in order to produce heating of the soil seed beds, install a heating cable in the prepared concrete screed, and then fill it with the specific layer of soil. There should be available reinforcing mesh and sand bags.
Conservatory and a greenhouse - these are special structures that are designed to grow vegetables, flowers, fruits and other plants in any season. Each of them need a special electrical heating system.
Heating of greenhouses and other buildings can get excellent results:
• Heated greenhouses promotes effective acceleration of growth of plants;
• Heated greenhouses can extend the season to collect the necessary crop;
• Heated greenhouses helps to grow exotic and heat-loving plants.
Heating conservatories, greenhouses, and cold framesis usually done by cable heating systems. Electric heating systems consists of electric heating heating cables with some power. This heating cable provides the necessary temperature for plants growing in greenhouses. Special cable provides heating the soil to the required temperature. This is all done as follows:
1. A specific layer of soil is taken off;
2. Then it is replased by special foundation of sand;
3. Insulating coating laid out;
4. Heating cable laid throughout the buildings, so that heating of greenhouses is the most effective;
5. all this layer of loose soil and watered with water.
Also, in order to produce heating of the soil seed beds, install a heating cable in the prepared concrete screed, and then fill it with the specific layer of soil. There should be available reinforcing mesh and sand bags.
Electric heating cable - a little theory.
Electric heating is one of the most common types of floor heating. In the device is placed in a certain way sex electric heating cable or tape. By this device the cable connects electricity through the heating thermostat. Electric warm floor heating cable is outwardly similar to conventional cable. Its main purpose - not to transfer to a distance of power and electrical signals and convert them to the thermoelectric current.
A small part of electricity in any drive or the cable is converted into heat. This energy is only 2%, while forcing a full range of measures to reduce it. With regard to heating cables, here the situation is reversed: 100% capacity should be transformed into heat, and its selection at the cable unit - it is the most important element of the heating cable. This process of heating cables are called specific heat.
Cable floor heating takes the form of specially selected heating mats, as well as sections. Presented heating sections are placed directly into the concrete screed, but the heating mats - in a special layer of tile adhesive, already on the outdated screed. In the heating elements used for heating cable of two types:
1.dvuhzhilny heating cable;
2.odnozhilny heating cable.
When laid solid conductors, then both ends folded into one single point, but when laying double-core cable, one end does not return to the starting point. Cable heating is quite effective way to provide heating floor. At the moment quite well known and quality is the warm floor Nexans, which is characterized by security of heating any room.
A small part of electricity in any drive or the cable is converted into heat. This energy is only 2%, while forcing a full range of measures to reduce it. With regard to heating cables, here the situation is reversed: 100% capacity should be transformed into heat, and its selection at the cable unit - it is the most important element of the heating cable. This process of heating cables are called specific heat.
Cable floor heating takes the form of specially selected heating mats, as well as sections. Presented heating sections are placed directly into the concrete screed, but the heating mats - in a special layer of tile adhesive, already on the outdated screed. In the heating elements used for heating cable of two types:
1.dvuhzhilny heating cable;
2.odnozhilny heating cable.
When laid solid conductors, then both ends folded into one single point, but when laying double-core cable, one end does not return to the starting point. Cable heating is quite effective way to provide heating floor. At the moment quite well known and quality is the warm floor Nexans, which is characterized by security of heating any room.
What is electric heating?
After all, it is well known that the house is a good host is distinguished not only beauty, but also warm. And electric heated floors - the sine qua non of comfort. Underfloor heating systems can be used as a supplementary source of heat in the harsh temperature zones, and used as a substitute in the middle and southern belts with a small spread of seasonal temperatures.
Currently, electric heating - this is the most acceptable from the standpoint of economy, security and ease of installation method of creating a comfortable temperature in the room. Cable heating - is the simplicity and convenience, cheapness and ease of operation. Applying an electric floor heating, you warrant comfort yourself and your loved ones.
Currently, electric heating - this is the most acceptable from the standpoint of economy, security and ease of installation method of creating a comfortable temperature in the room. Cable heating - is the simplicity and convenience, cheapness and ease of operation. Applying an electric floor heating, you warrant comfort yourself and your loved ones.
Types of Y Strainers
A Y strainer, as the name suggests, is shaped like a Y. These are used in liquid of gas pressurized lines and also in vacuum and suction conditions. Y strainers are used to capture the solids; and screen collecting the solids must be cleaned at regular intervals.
There are basically two common types of Y strainers and they are:
· NPT threaded – These are primarily used to strain dirt from pipelines thereby providing protection to meters, pumps, turbines, traps and compressors. The connections can be either socket weld or screwed.
· Flanged – In these Y strainers the connections are flanged and these are also used to separate dirt from fluids in pipelines. These are used more often in the dental industry.
The best part is that Y strainers can be made of a variety of materials and hence each of the above mentioned options can be made of either of the following:
Brazed plate heat exchangers are used in combination with Y strainers to deliver the best results. These exchangers are used to transfer heat from one liquid to another extremely efficiently and effectively. It usually has stainless steel plates brazed together and is compatible with a number of fluids.
There are basically two common types of Y strainers and they are:
· NPT threaded – These are primarily used to strain dirt from pipelines thereby providing protection to meters, pumps, turbines, traps and compressors. The connections can be either socket weld or screwed.
· Flanged – In these Y strainers the connections are flanged and these are also used to separate dirt from fluids in pipelines. These are used more often in the dental industry.
The best part is that Y strainers can be made of a variety of materials and hence each of the above mentioned options can be made of either of the following:
- Cast iron
- Bronze
- Cast steel
- Stainless steel
Brazed plate heat exchangers are used in combination with Y strainers to deliver the best results. These exchangers are used to transfer heat from one liquid to another extremely efficiently and effectively. It usually has stainless steel plates brazed together and is compatible with a number of fluids.
Heating Fundamentals: Heat and Work relationship
Heat is a form of energy in transit between its source and destination point as a result of temperature differences between them. Heat energy exists as such only while flowing between the source and destination.
Prior to 1929, Btu was defined as the amount of heat necessary to raise the temperature of one pound of water by one degree Fahrenheit. Due to the difficulty in measuring an exact value of a Btu, it was later defined in terms of the more fundamental physical unit.
Since 1929, British thermal unit has been defined on the following basis:
1 Btu = 251.996 IT (International Steam Table) calories =778.26 foot-pounds of mechanical energy units (works) = approximately 1/3 watt-hour.
Work is measured by a foot-pound. Foot-pound may be defined as the amount of work done in raising one pound a distance of one foot, or overcoming a pressure of one pound through a distance of one foot.
The relationship between heat and work is called a mechanical equivalent of heat. One unit of heat being equal to 778.26 ft-lb.
1 Btu = 778.26 ft-lb
British Thermal Unit
Heat energy is measured by British thermal unit (Btu). Each thermal unit is regarded as equivalent of one unit of heat (heat energy).Prior to 1929, Btu was defined as the amount of heat necessary to raise the temperature of one pound of water by one degree Fahrenheit. Due to the difficulty in measuring an exact value of a Btu, it was later defined in terms of the more fundamental physical unit.
Since 1929, British thermal unit has been defined on the following basis:
1 Btu = 251.996 IT (International Steam Table) calories =778.26 foot-pounds of mechanical energy units (works) = approximately 1/3 watt-hour.
Heat and Work relationship
Work is the overcoming of resistance through a certain distance by the expenditure of energy.Work is measured by a foot-pound. Foot-pound may be defined as the amount of work done in raising one pound a distance of one foot, or overcoming a pressure of one pound through a distance of one foot.
The relationship between heat and work is called a mechanical equivalent of heat. One unit of heat being equal to 778.26 ft-lb.
1 Btu = 778.26 ft-lb
Advantages of Forced Warm Air Heating System (FWA)
The advantages of (FWA) forced-warm-air heating system are as follows:
- Lower installation costs than those for hot water or steam heating systems.
- Heat delivery is usually quicker than in other heating systems.
- Heat delivery can be shut off immediately.
- Air filters replacement is easier, cheaper and quicker than maintenance for other types of heating systems.
- Humidity level of the air can be controlled more easily.
- Air conditioning can be added without incurring great expenses.
- Furnace can be placed in a number of different locations in a building structure.
Disadvantages of (FWA) forced-warm-air heating system are as follows:
- Noise: Both the operation of the blower and the expansion and contraction of the ducts as the air temperature rises or falls can cause distracting noise.
- Furniture placement and room decorating problems: in order to operate effectively, furniture or carpets should not block warm-air outlets. This restricts furniture arrangement and placement of carpets.
- Dust: Ordinary filters remove larger dust particles, but are not very effective against the smaller ones. High air turbulence results in dust deposits on walls, furniture, and other surfaces.
- Various room temperatures: Forced-warm air heating systems supply convected heat through forced-air movements, which results in bursts, when the thermostat temperature is adjusted, rather than continuous steady flow. Temperature variations can be reduced if by setting the fan switch for continuous blower operation.
- Lower installation costs than those for hot water or steam heating systems.
- Heat delivery is usually quicker than in other heating systems.
- Heat delivery can be shut off immediately.
- Air filters replacement is easier, cheaper and quicker than maintenance for other types of heating systems.
- Humidity level of the air can be controlled more easily.
- Air conditioning can be added without incurring great expenses.
- Furnace can be placed in a number of different locations in a building structure.
Disadvantages of (FWA) forced-warm-air heating system are as follows:
- Noise: Both the operation of the blower and the expansion and contraction of the ducts as the air temperature rises or falls can cause distracting noise.
- Furniture placement and room decorating problems: in order to operate effectively, furniture or carpets should not block warm-air outlets. This restricts furniture arrangement and placement of carpets.
- Dust: Ordinary filters remove larger dust particles, but are not very effective against the smaller ones. High air turbulence results in dust deposits on walls, furniture, and other surfaces.
- Various room temperatures: Forced-warm air heating systems supply convected heat through forced-air movements, which results in bursts, when the thermostat temperature is adjusted, rather than continuous steady flow. Temperature variations can be reduced if by setting the fan switch for continuous blower operation.
Heating and Cooling systems
The heating and cooling system is the heart of the house. When buying a house, at least you need to know:
- what kind of heating and cooling system is in place?
- what condition it is now?
- how much does it cost to operate?
The most common heating systems include:
- what kind of heating and cooling system is in place?
- what condition it is now?
- how much does it cost to operate?
Heating system types:
The most common heating systems include:
1) Forced Warm Air (FWA)
This is the most common type of the heating system. A furnace heats air, and a blower sends the hot air through the house. Return vents and pipes bring the cool air back to the furnace to be heated. Furnaces have a capacity rated in BTU's, which are simply British Thermal Units. The number of BTU's given represents the furnace's heat output from either gas, oil or electric firing.2) Steam heating system
This kind of system usually found in older homes. A furnace heats water until steam forms. The steam circulates through pipes into radiators in the rooms. As steam cools, it turns back into water, which then returns to the furnace.3) Hot water heating
This system works like a steam heat, but instead of circulating steam, it circulates hot water that heats the rooms.4) Baseboard / electric heating
This system uses heating elements placed along the baseboards of walls.5) Radiant heating system
This type of system uses pipes built into the floor and/or walls to heat the rooms.Energy Guide labels
Heating and cooling systems are some of the most important investments that can be made for the home. Buying a new house? Renovating an old one? Making an emergency purchase because the old one finally conked out? A lot depends on the choices you make. Comfort and safety are at stake, and so your money.
According to the Department of Energy (DOE), typically about 45 % of utility bills goes toward “space conditioning,” or heating and cooling a home. While the price of equipment and cost of repairs and maintenance are important to consider, do not forget about system operating costs. Hefty space conditioning costs may be lowered by choosing the most energy-efficient equipment that meets your needs and fits your budget.
The Federal Trade Commission, the nation’s consumer protection agency, wants you to know that it enforces the Appliance Labeling Rule, which requires EnergyGuide labels on certain appliances, including:
• room and central air conditioners,
• furnaces, boilers and heat pumps.
The labels let you know how energy efficient a model is compared to others like it.
According to the Department of Energy (DOE), typically about 45 % of utility bills goes toward “space conditioning,” or heating and cooling a home. While the price of equipment and cost of repairs and maintenance are important to consider, do not forget about system operating costs. Hefty space conditioning costs may be lowered by choosing the most energy-efficient equipment that meets your needs and fits your budget.
The Federal Trade Commission, the nation’s consumer protection agency, wants you to know that it enforces the Appliance Labeling Rule, which requires EnergyGuide labels on certain appliances, including:
• room and central air conditioners,
• furnaces, boilers and heat pumps.
The labels let you know how energy efficient a model is compared to others like it.
Koi Pond Heaters
There are many reasons for heating your koi pond, maybe you just want to see your enjoy your pond in all seasons. Whatever your reason we just want to give you some insight to make it easy to accomplish. There is now new technology, energy efficient heaters being developed for pond heating. Therefore we recommend electric koi pond heaters, submersible heaters, heat exchangers and floating pond heaters.
Pond heating Considerations:
First you must determine whether you want to de-ice or actually heat your pond to a specific temperature. Deicers melt the ice to provide an opening for harmful gas exchange only. Heating your pond to obtain a specific temperature can be a bit technical, so if your not sure about the heater sizing we recommend that you contact our koi pond heating specialists. The outside low temperature is the key to your kilowatt requirements and unfortunately it can vary. Your heater output kilowatts are calculated based on your low ambient temperature and if your geographical area drops far below that normal low temperature a safety factor should be included in the calculations. We recommend submersible pond heaters for small to medium size ponds and energy efficient heat exchangers for large ponds
Koi Pond Information:
One period when koi keepers traditionally have their most difficult time with health problems is during the transition from winter to spring. As waters begin to warm up, pathogens are able to multiply at a more rapid rate than koi can defend themselves leading to an increase in the likelihood of disease. If a pond is heated over winter, then this risky period is removed from the koi owners. View info Pond Heaters
The major reasons for pond heater failures:
Pond water is usually high in calcium chloride and other minerals,this causes build up on heaters. In time the build up prevents heat transfer and the heater internally burns out. Our new technology completely eliminates any build up.
Salt additives to pond water eventually corrodes the heater surface. We have developed heaters that can’t be attacked chemically. The most popular cause of pond heater failure is low liquid burnout. Our new pond heaters don't burn from lack of liquid, they can run in air and will shut themselves down before burnout. Visit our web site Heating Your Pond.
By Kirk Rogers
Pond heating Considerations:
First you must determine whether you want to de-ice or actually heat your pond to a specific temperature. Deicers melt the ice to provide an opening for harmful gas exchange only. Heating your pond to obtain a specific temperature can be a bit technical, so if your not sure about the heater sizing we recommend that you contact our koi pond heating specialists. The outside low temperature is the key to your kilowatt requirements and unfortunately it can vary. Your heater output kilowatts are calculated based on your low ambient temperature and if your geographical area drops far below that normal low temperature a safety factor should be included in the calculations. We recommend submersible pond heaters for small to medium size ponds and energy efficient heat exchangers for large ponds
Koi Pond Information:
One period when koi keepers traditionally have their most difficult time with health problems is during the transition from winter to spring. As waters begin to warm up, pathogens are able to multiply at a more rapid rate than koi can defend themselves leading to an increase in the likelihood of disease. If a pond is heated over winter, then this risky period is removed from the koi owners. View info Pond Heaters
The major reasons for pond heater failures:
Pond water is usually high in calcium chloride and other minerals,this causes build up on heaters. In time the build up prevents heat transfer and the heater internally burns out. Our new technology completely eliminates any build up.
Salt additives to pond water eventually corrodes the heater surface. We have developed heaters that can’t be attacked chemically. The most popular cause of pond heater failure is low liquid burnout. Our new pond heaters don't burn from lack of liquid, they can run in air and will shut themselves down before burnout. Visit our web site Heating Your Pond.
By Kirk Rogers
Koi Pond Heating
There are many reasons for heating your koi pond,maybe you just want to see your enjoy your pond in all seasons.Whatever your reason we just want to give you some insight to make it easy to accomplish. There is now new technology,enery efficient heaters being developed for pond heating.Therefore we recommend electric koi pond heaters,submersible heaters,heat exchangers and floating pond heaters.Pond heating Considerations: First you must determine whether you want to de-ice or actually heat your pond to a specific temperature .Deicers melt the ice to provide an opening for harmful gas exchange only. Heating your pond to obtain a specific temperature can be a bit technical, so if your not sure about the heater sizing we recommend that you contact our koi pond heating specialists. The outside low temperature is the key to your kilowatt requirements and unfortunately it can vary. Your heater output kilowatts are calculated based on your low ambient temperature and if your geographical area drops far below that normal low temperature a safety factor should be included in the calculations.We recommend submersible pond heaters for small to medium size ponds and energy efficient heat exchangers for large ponds.
* Pond Heating: There are conditions that effect pond heaters and make it more difficult controlling pond temperature.
* Pond Waterfalls are used for aeration and beauty,but they cool the water and work against the heating process.
* Pond Water Depth a good designed koi pond should be at least three foot in depth,shallow large exposed surface area ponds are easily effected by wind chill factors and require larger pond heaters to maintain temperature.
Koi Pond Information: One period when koi keepers traditionally have their most difficult time with health problems is during the transition from winter to spring. As waters begin to warm up, pathogens are able to multiply at a more rapid rate than koi can defend themselves leading to an increase in the likelihood of disease. If a pond is heated over winter, then this risky period is removed from the koi owners.
Do not raise the koi's water temperature too fast. Parasites and bacteria can also grow more quickly in warm water. The fishes system takes time to adjust but the disease organisms do not. Raise the temperature from ambient at 3 - 5 degree intervals every 24 hours to 80 - 84 degrees Fahrenheit. Maintain a stable temperature with less than 2 degrees variable per day Treat with 0.3% salt and parasiticides or antibiotics during the adjustment period, and continue with medication if necessary until cure is affected. Maintain temp. for 4 - 6 weeks after cure, then slowly drop the temperature to match that of the pond water. This will ensure a stronger Koi and ease the fishes transition back to the pond.
By Kirk Rogers
* Pond Heating: There are conditions that effect pond heaters and make it more difficult controlling pond temperature.
* Pond Waterfalls are used for aeration and beauty,but they cool the water and work against the heating process.
* Pond Water Depth a good designed koi pond should be at least three foot in depth,shallow large exposed surface area ponds are easily effected by wind chill factors and require larger pond heaters to maintain temperature.
Koi Pond Information: One period when koi keepers traditionally have their most difficult time with health problems is during the transition from winter to spring. As waters begin to warm up, pathogens are able to multiply at a more rapid rate than koi can defend themselves leading to an increase in the likelihood of disease. If a pond is heated over winter, then this risky period is removed from the koi owners.
Do not raise the koi's water temperature too fast. Parasites and bacteria can also grow more quickly in warm water. The fishes system takes time to adjust but the disease organisms do not. Raise the temperature from ambient at 3 - 5 degree intervals every 24 hours to 80 - 84 degrees Fahrenheit. Maintain a stable temperature with less than 2 degrees variable per day Treat with 0.3% salt and parasiticides or antibiotics during the adjustment period, and continue with medication if necessary until cure is affected. Maintain temp. for 4 - 6 weeks after cure, then slowly drop the temperature to match that of the pond water. This will ensure a stronger Koi and ease the fishes transition back to the pond.
By Kirk Rogers
The Importance of Keeping your Heat Exchanger Clean
An air-to-water heat exchanger is highly specialized equipment intended to be used when ambient or air temperatures are higher than 130 degrees Fahrenheit. Industrial air conditioners are unable to cool machinery when the ambient temperature is at that level, because the refrigerant their compressors produce is at around 150 degrees Fahrenheit, and there is too little difference between the two temperatures for the refrigerant to do its job. In cases such as these, air-to-water heat exchangers come into play. They bring the enclosure interior below the temperature of the ambient air so that the equipment can function properly.
At its most basic, heat exchanger air water cleaning is simply making certain that both the air and the water utilized to dissipate the heat from your process system are kept clean. If for instance the mechanism of your system that brings in the air is a cooling tower, you will have to realize that when it brings the air into your system, all the debris that happens to be in the air will enter the system along with it. This debris can then enter the system, build up within it, and restrict proper operation – and eventually cause a malfunction, perhaps even a serious one. So simply keeping your heat exchanger system clean would appear to be the solution to this problem.
However, critics have compared this to taking a cold tablet when one has a cold, and with good reason. While cleaning the heat-exchange system will ensure that it is free of anything that could cause problems, it does nothing whatsoever to prevent the problem from recurring, especially in areas where there is plenty of debris that could potentially cause some sort of jam. In that sense, simple cleaning will not be enough.
The ultimate solution, then, would be to install excellent filtration technology to keep the debris from entering the system in the first place, and combine this with diligent cleaning.
So ensure that you install the proper filters and filtration technology and religiously perform your heat exchanger air water cleaning operations to enable your entire system to function optimally.
By Sabrina Rocca
Cleaning Your Heat Exchanger Tubes
Cleaning your heat exchanger tubes is a job anyone can do if they know how. If you are a do it yourselfer then you should have no trouble with this task.
There are several methods to clean exchanger tubes. Here are a few of them; one is to use chemicals for the cleaning. Another is to use high-pressure water system. One last method is to employ mechanical cleaning using brushes, scrapers and abrasive balls. These are the best ways to clean the tubes.
Regular cleaning of the exchanger tubes should prolong the life of the entire unit. It will help it work at its maximum efficiency as well.
Many people use a heat exchanger system to heat their swimming pools these days. Having the ability to clean your own exchanger tubes would be a good way to save money and keep your system in top working order.
It would be beneficial to clean the exchanger tubes every few months. At least inspect them to see if they need to be cleaned. If they do not need to be cleaned, and then make sure that, they are thoroughly cleaned twice a year.
In order to clean the exchanger tubes properly, they must be removed from the system. Remove any loose material that is near the ends of the tubes and inside them as well. Use a brush and push it down the tube to get the cleaning started. The brush should have good strong nylon bristles. This helps to loosen and remove any loose materials inside.
During this brushing process, you may find that there is some material stuck to the sidewall of the exchanger tube. A plastic or metal scraper will help to remove anything that is stuck to the wall. Be careful not to damage the tube. Do not use a scraper that is harder than the material of the wall of the tube.
Try not to scratch the wall of the exchanger tubes as it could cause the tube to not function as well as it should because particles could stick to the scratches in the tube. Therefore, a plastic scraper would be best.
As a last step in cleaning the exchanger tubes, you could use a water jet to force out any loose particles that were missed with the previous methods. If you have any calcium deposits on the tubes then you will need chemicals to remove them.
Now you have the basics for cleaning your exchanger tubes. Gather as much information as possible before tackling this do it yourself job.
By M. Applebaum
(ArticlesBase SC #720822)
There are several methods to clean exchanger tubes. Here are a few of them; one is to use chemicals for the cleaning. Another is to use high-pressure water system. One last method is to employ mechanical cleaning using brushes, scrapers and abrasive balls. These are the best ways to clean the tubes.
Regular cleaning of the exchanger tubes should prolong the life of the entire unit. It will help it work at its maximum efficiency as well.
Many people use a heat exchanger system to heat their swimming pools these days. Having the ability to clean your own exchanger tubes would be a good way to save money and keep your system in top working order.
It would be beneficial to clean the exchanger tubes every few months. At least inspect them to see if they need to be cleaned. If they do not need to be cleaned, and then make sure that, they are thoroughly cleaned twice a year.
In order to clean the exchanger tubes properly, they must be removed from the system. Remove any loose material that is near the ends of the tubes and inside them as well. Use a brush and push it down the tube to get the cleaning started. The brush should have good strong nylon bristles. This helps to loosen and remove any loose materials inside.
During this brushing process, you may find that there is some material stuck to the sidewall of the exchanger tube. A plastic or metal scraper will help to remove anything that is stuck to the wall. Be careful not to damage the tube. Do not use a scraper that is harder than the material of the wall of the tube.
Try not to scratch the wall of the exchanger tubes as it could cause the tube to not function as well as it should because particles could stick to the scratches in the tube. Therefore, a plastic scraper would be best.
As a last step in cleaning the exchanger tubes, you could use a water jet to force out any loose particles that were missed with the previous methods. If you have any calcium deposits on the tubes then you will need chemicals to remove them.
Now you have the basics for cleaning your exchanger tubes. Gather as much information as possible before tackling this do it yourself job.
By M. Applebaum
(ArticlesBase SC #720822)
The use of plate heat exchange equipment for winemaking
In the winemaking process heat exchange equipment is used at all stages of the process, such as for processing grapes, mash, to accelerate the maturation of wines. It used for specialized types of wines, as well as filling and in the production of sparkling wine - in preparing the fermentation mixture, the secondary fermentation, bottling of the finished champagne, the stabilization of brandies, to accelerate maturation of brandy spirits.
This is because the heating and cooling, as purely physical methods of impact on the wine, not associated with the introduction into it of other, not peculiar substances. On the other hand, these techniques cause the complex physics-chemical and biochemical processes, many of which are similar to the processes taking place during maturation and aging of wine in the wild. For all these technological stages, heat transfer equipment of various types is used, and, in the first place - frame plate heat exchangers.
Heat transfer surface of the plate heat exchanger consists of a set of plates with seals, pairs of lines for the passage of fluids. Pack plates secured between the stationary and the pressure plate and hermetically tightened bolts.
Figure 1: Construction of one-section plate heat exchanger
The plates are assembled into the package through many contact points, thus ensuring resistance of the design to high pressure. Corrugation pattern of the plates enhances turbulence, and reduces the probability of sediments on the plate surface. The minimum temperature difference between heating medium inlet and outlet can be 1 ° C, which is particularly valuable for the section of regeneration in the pasteurization equipment.
Package can consist of plates with different corrugation patterns.
Plates with horizontally oriented profile characterized by high heat transfer rates with relatively large pressure differences, whereas for a plate with a vertically oriented profiles are characterized by small variations in pressure with less heat transfer rates.
Combining the horizontal and vertical profiles can obtain the optimal values of hydraulic resistance and heat transfer coefficients.
Large variety of types of plates makes effective use of plate heat exchangers for different processes.
This is because the heating and cooling, as purely physical methods of impact on the wine, not associated with the introduction into it of other, not peculiar substances. On the other hand, these techniques cause the complex physics-chemical and biochemical processes, many of which are similar to the processes taking place during maturation and aging of wine in the wild. For all these technological stages, heat transfer equipment of various types is used, and, in the first place - frame plate heat exchangers.
Heat transfer surface of the plate heat exchanger consists of a set of plates with seals, pairs of lines for the passage of fluids. Pack plates secured between the stationary and the pressure plate and hermetically tightened bolts.
Figure 1: Construction of one-section plate heat exchanger
The plates are assembled into the package through many contact points, thus ensuring resistance of the design to high pressure. Corrugation pattern of the plates enhances turbulence, and reduces the probability of sediments on the plate surface. The minimum temperature difference between heating medium inlet and outlet can be 1 ° C, which is particularly valuable for the section of regeneration in the pasteurization equipment.
Package can consist of plates with different corrugation patterns.
Plates with horizontally oriented profile characterized by high heat transfer rates with relatively large pressure differences, whereas for a plate with a vertically oriented profiles are characterized by small variations in pressure with less heat transfer rates.
Combining the horizontal and vertical profiles can obtain the optimal values of hydraulic resistance and heat transfer coefficients.
Large variety of types of plates makes effective use of plate heat exchangers for different processes.
How Heat Transfer Works
Heat transfer occurs when there is a difference in temperature between two mediums. Heat will travel from the hot source to the cold source. The rate at which the heat transfer occurs at is determined by many factors such as the heat conductivity of the two materials andthe difference in temperatures of the two mediums. Convectiuve heat transfer occurs when the materials are moving against each other.
Plate heat exchangers have significantly good heat transfer rates because they use metal plates which have high heat conductivity rates and the plates are extremely thin. The plate heat exchangers also achieve high amounts of heat transfer through convective forces with both working fluids. With large temperature differentials, great amounts of heat transfer can be achieved using a plate heat exchanger.
Plate heat exchangers have significantly good heat transfer rates because they use metal plates which have high heat conductivity rates and the plates are extremely thin. The plate heat exchangers also achieve high amounts of heat transfer through convective forces with both working fluids. With large temperature differentials, great amounts of heat transfer can be achieved using a plate heat exchanger.
Compact heat exchangers
Applications and advantages of brazed heat exchangers
Brazed plate heat exchangers are designed for highly efficient transfer of energy between liquid, vapor and gaseous environments.
Brazed plate heat exchangers have the following advantages:
- High reliability due to design features and advanced technology manufacturing;
- High efficiency plate heat exchanger;
- Wide range of operating temperatures;
- High working pressure;
- High corrosion resistance of plate heat exchanger;
- Compactness and light weight plate heat exchanger;
- Small internal volume;
- Wide range of capacities and dimensions;
- Ease of installation and maintenance of plate heat exchanger;
- Low cost of plate heat exchanger.
Applications of brazed plate heat exchangers:
- Heating and hot water (steam and water heaters);
- Ventilation systems;
- Air conditioning in rooms and buildings;
- Refrigeration: Evaporators, Condensers;
- Consisting of heat pumps: evaporators, condensers, intermediate heaters and coolers;
- For different technological needs (coolers, heaters);
- Water heaters in pools, etc.
Brazed plate heat exchangers have the following advantages:
- High reliability due to design features and advanced technology manufacturing;
- High efficiency plate heat exchanger;
- Wide range of operating temperatures;
- High working pressure;
- High corrosion resistance of plate heat exchanger;
- Compactness and light weight plate heat exchanger;
- Small internal volume;
- Wide range of capacities and dimensions;
- Ease of installation and maintenance of plate heat exchanger;
- Low cost of plate heat exchanger.
Applications of brazed plate heat exchangers:
- Heating and hot water (steam and water heaters);
- Ventilation systems;
- Air conditioning in rooms and buildings;
- Refrigeration: Evaporators, Condensers;
- Consisting of heat pumps: evaporators, condensers, intermediate heaters and coolers;
- For different technological needs (coolers, heaters);
- Water heaters in pools, etc.
The design of brazed plate heat exchangers
Brazed Heat Exchangers consist of high quality steel plates that are vacuum brazed into one compact, pressure resistant block. For the solder are widely used copper or nickel. In assembling each second plate is rotated 180 degrees, forming a channel separation for the heat transfer medium.
For special applications (depending on type) may create a parallel stream media. Some profile plates or extra built-in turbulence plate provides a high degree of turbulence, which ensures efficient heat transfer even at low volume and reduces costs to a minimum the risk of contamination.
Heat exchangers for chiller applications
Understanding the thermodynamic and transport properties of fluids - combined with simple calculations to define a specific heat transfer problem - will help you select the appropriate heat exchanger for your liquid chiller application.
Numerous types of heat exchangers are used in chiller applications. They serve the specific purpose of controlling a system’s temperature by removing thermal energy. Although there are numerous sizes, levels of complexity and types of heat exchangers, they all use a thermally conducting element, typically in the form of a tube or plate, to separate two fluids so that one can transfer energy to the other.
When selecting the proper type of heat exchanger, one faces the fundamental challenge of fully defining the problem to be solved, which requires an understanding of thermodynamic and transport properties of fluids. This knowledge can be combined with simple calculations to define a specific heat transfer problem and to select the appropriate heat exchanger to use.
Fluid Flow Properties
Fluid flow inside the heat exchanger is a major consideration when selecting what type of exchanger is the best choice in a specific application. Fluid flow will be either turbulent or laminar. Laminar flow heat transfer relies entirely on the thermal conductivity of fluid to transfer heat to the heat exchanger surface. Laminar flows have lower film coefficients than turbulent flows.
Turbulent flows rely not only on thermal conduction but also thermal convection due to the increased fluid movement created in this type flow, thus producing better heat transfer. The higher film coefficients create less resistance to heat transfer.
The heat exchanger’s fluid flow can be determined from its Reynolds number. If the Reynolds number is less than 2,300, the fluid flow will be laminar. Fully turbulent fluid flow has a Reynolds number greater than 10,000. The transition region between laminar and turbulent flow produces higher thermal performance as the Reynolds number increases.
The type of flow determines how much pressure a fluid loses as it moves through the heat exchanger. This factor is important because higher pressure drops require greater pumping requirements. Laminar flow produces less pressure drop and increases linearly with the flow velocity.
This heat exchanger consists of a vertical set of plates welded together to form a cavity through which the colder fluid flows while the hotter fluid flows over the outside of the plates. The hot fluid cools as the fluid film flows down the plates. Most falling-film plates are embossed with intermittent welds placed throughout the plate surface. They can be single (top right) or double (bottom right) embossed.
Many types of heat exchangers are utilized in chiller applications. These range from shell and tube, brazed plate, semi-welded plate, welded plate and vertical falling-film plate. Each has specific characteristics that should be considered during the engineering selection process of a chiller system.
Shell-and-tube heat exchangers are used in applications where high temperatures and pressure demands are of great consequence. This type of design consists of a bundle of parallel tubes typically in a U-tube configuration. The bundle is supported by a series of baffles, which also helps to direct the flow across the tubes. Tubesheets close the ends and separate the two fluids.
The process fluid typically flows through the tubes to take advantage of the higher pressure capabilities inside the tubes and ease cleaning. The thermal performance of the shell-and-tube design generally is less than a plate design but the pressure rating is generally higher.
Brazed plate heat exchangers, like other plate heat exchangers, provide higher turbulent flow and heat transfer coefficients in a much smaller footprint. The plate material is typically AISI 316 type stainless steel. The herringbone plates are vacuum brazed to form the heat exchanger.
Brazed plate heat exchangers provide a highly efficient compact unit that will conserve space and reduce fluid volume requirements. Dual-circuit and double-wall models allow for numerous design options. The major factor to take into consideration is the fouling factor of the smaller channels. Because these units cannot be dismantled, filtration should be used on these heat exchangers.
Another variation of plate heat exchangers is the semi-welded plate heat exchanger. This type of heat exchanger utilizes the chevron-plate design to increase turbulent flow within the plate channels. The semi-welded heat exchanger consists of two plates laser-welded together into what is called a cassette. Plate gaskets seal between each cassette, and the cassettes are bolted together between end frames to retain the complete cassette pack. One fluid flows in the welded channel while the other flows through the gasketed channel.
Semi-welded plate heat exchangers have the same inherent advantages as all plate designs: higher turbulent flows, greater heat transfer coefficients and reduced fluid volume requirements. The largest difference with this design is the opportunity for expansion and ease of opening the unit for repair or cleaning. Cassettes can be added to increase the capacity of the heat exchanger.
The vertical falling-film plate heat exchanger design takes advantage of a large surface area for heat and mass transfer at the boundary of the two fluid flows. This design utilizes a vertical set of plates welded together to form a cavity through which the colder fluid flows. The hotter fluid flows over the external sides of the plates and is cooled when the film of fluid flows down the plate length. Typically, the plates are made of stainless steel for compatibility with sanitary fluids. An upper pan controls the external fluid flow with holes located over the plates.
This type heat exchanger allows closer approach temperatures between the fluids. The internal design of the plate cavity is critical. Most of these type of plates have an embossed design with intermittent welds throughout the plate surface. This helps to increase the turbulent flow inside the plates for higher heat transfer coefficients.
By considering the characteristics of the different types of heat exchangers at the beginning of a chiller selection, a more efficient system can be achieved.
Numerous types of heat exchangers are used in chiller applications. They serve the specific purpose of controlling a system’s temperature by removing thermal energy. Although there are numerous sizes, levels of complexity and types of heat exchangers, they all use a thermally conducting element, typically in the form of a tube or plate, to separate two fluids so that one can transfer energy to the other.
When selecting the proper type of heat exchanger, one faces the fundamental challenge of fully defining the problem to be solved, which requires an understanding of thermodynamic and transport properties of fluids. This knowledge can be combined with simple calculations to define a specific heat transfer problem and to select the appropriate heat exchanger to use.
Fluid Flow Properties
Fluid flow inside the heat exchanger is a major consideration when selecting what type of exchanger is the best choice in a specific application. Fluid flow will be either turbulent or laminar. Laminar flow heat transfer relies entirely on the thermal conductivity of fluid to transfer heat to the heat exchanger surface. Laminar flows have lower film coefficients than turbulent flows.
Turbulent flows rely not only on thermal conduction but also thermal convection due to the increased fluid movement created in this type flow, thus producing better heat transfer. The higher film coefficients create less resistance to heat transfer.
The heat exchanger’s fluid flow can be determined from its Reynolds number. If the Reynolds number is less than 2,300, the fluid flow will be laminar. Fully turbulent fluid flow has a Reynolds number greater than 10,000. The transition region between laminar and turbulent flow produces higher thermal performance as the Reynolds number increases.
The type of flow determines how much pressure a fluid loses as it moves through the heat exchanger. This factor is important because higher pressure drops require greater pumping requirements. Laminar flow produces less pressure drop and increases linearly with the flow velocity.
This heat exchanger consists of a vertical set of plates welded together to form a cavity through which the colder fluid flows while the hotter fluid flows over the outside of the plates. The hot fluid cools as the fluid film flows down the plates. Most falling-film plates are embossed with intermittent welds placed throughout the plate surface. They can be single (top right) or double (bottom right) embossed.
Many types of heat exchangers are utilized in chiller applications. These range from shell and tube, brazed plate, semi-welded plate, welded plate and vertical falling-film plate. Each has specific characteristics that should be considered during the engineering selection process of a chiller system.
Shell-and-tube heat exchangers are used in applications where high temperatures and pressure demands are of great consequence. This type of design consists of a bundle of parallel tubes typically in a U-tube configuration. The bundle is supported by a series of baffles, which also helps to direct the flow across the tubes. Tubesheets close the ends and separate the two fluids.
The process fluid typically flows through the tubes to take advantage of the higher pressure capabilities inside the tubes and ease cleaning. The thermal performance of the shell-and-tube design generally is less than a plate design but the pressure rating is generally higher.
Brazed plate heat exchangers, like other plate heat exchangers, provide higher turbulent flow and heat transfer coefficients in a much smaller footprint. The plate material is typically AISI 316 type stainless steel. The herringbone plates are vacuum brazed to form the heat exchanger.
Brazed plate heat exchangers provide a highly efficient compact unit that will conserve space and reduce fluid volume requirements. Dual-circuit and double-wall models allow for numerous design options. The major factor to take into consideration is the fouling factor of the smaller channels. Because these units cannot be dismantled, filtration should be used on these heat exchangers.
Another variation of plate heat exchangers is the semi-welded plate heat exchanger. This type of heat exchanger utilizes the chevron-plate design to increase turbulent flow within the plate channels. The semi-welded heat exchanger consists of two plates laser-welded together into what is called a cassette. Plate gaskets seal between each cassette, and the cassettes are bolted together between end frames to retain the complete cassette pack. One fluid flows in the welded channel while the other flows through the gasketed channel.
Semi-welded plate heat exchangers have the same inherent advantages as all plate designs: higher turbulent flows, greater heat transfer coefficients and reduced fluid volume requirements. The largest difference with this design is the opportunity for expansion and ease of opening the unit for repair or cleaning. Cassettes can be added to increase the capacity of the heat exchanger.
The vertical falling-film plate heat exchanger design takes advantage of a large surface area for heat and mass transfer at the boundary of the two fluid flows. This design utilizes a vertical set of plates welded together to form a cavity through which the colder fluid flows. The hotter fluid flows over the external sides of the plates and is cooled when the film of fluid flows down the plate length. Typically, the plates are made of stainless steel for compatibility with sanitary fluids. An upper pan controls the external fluid flow with holes located over the plates.
This type heat exchanger allows closer approach temperatures between the fluids. The internal design of the plate cavity is critical. Most of these type of plates have an embossed design with intermittent welds throughout the plate surface. This helps to increase the turbulent flow inside the plates for higher heat transfer coefficients.
By considering the characteristics of the different types of heat exchangers at the beginning of a chiller selection, a more efficient system can be achieved.
Biological Fouling
The attachment of microorganisms (bacteria, algae, and fungi) and macroorganisms (barnacles, sponges, fishes, seaweed, etc.) on heat-transfer surfaces where the cooling water is used in as drawn condition from river, lake, sea and coastal water, etc., is commonly referred to as biological fouling. On contact with heat-transfer surfaces, these organisms can attach and breed, sometimes completely clogging the fluid passages, as well as entrapping silt or other suspended solids and giving rise to deposit corrosion. Concentration of microorganisms in cooling-water systems may be relatively low before problems of biofouling are initiated. Corrosion due to biological attachment to heat transfer surfaces is known as microbiologically influenced corrosion.
The techniques that can be effective in controlling biological fouling include the following:
1. Select materials that posses good biocidal properties.
2. Mechanical cleaning techniques like upstream filtration, air bumping, back flushing, passing brushes, sponge rubber balls, grit coated rubber balls, and scrapers.
3. Chemical cleaning techniques that employ biocides such as chlorine, chlorine dioxide, bromine, ozone, surfactants, pH changes, and/or salt additions.
4. Thermal shock treatment by application of heat, or deslugging with steam or hot water.
5. Ultraviolet radiation.
The techniques that can be effective in controlling biological fouling include the following:
1. Select materials that posses good biocidal properties.
2. Mechanical cleaning techniques like upstream filtration, air bumping, back flushing, passing brushes, sponge rubber balls, grit coated rubber balls, and scrapers.
3. Chemical cleaning techniques that employ biocides such as chlorine, chlorine dioxide, bromine, ozone, surfactants, pH changes, and/or salt additions.
4. Thermal shock treatment by application of heat, or deslugging with steam or hot water.
5. Ultraviolet radiation.
Fouling Resistance - Impurities
Fluids are rarely pure. Intrusion of minute amounts of impurities can initiate or substantially increase fouling. They can either deposit as a fouling layer or acts as catalysts to the fouling processes.
In crystallization fouling, the presence of small particles of impurities may initiate the deposition process by seeding. Sometimes impurities such as sand or other suspended particles in cooling water may have a scouring action, which will reduce or remove deposits.
Read the full article about fouling resistance.
In crystallization fouling, the presence of small particles of impurities may initiate the deposition process by seeding. Sometimes impurities such as sand or other suspended particles in cooling water may have a scouring action, which will reduce or remove deposits.
Read the full article about fouling resistance.
Fouling Resistance -Velocity and Hydrodynamic Effects
Some of the parameters that known to influence fouling resistance are:
Velocity and Hydrodynamic Effects
Hydrodynamic effects, such as flow velocity and shear stress at the surface, influence fouling. Within the pressure drop considerations, the higher the velocity, higher will be the thermal performance of the exchanger and less will be the fouling. Uniform and constant flow of process fluids past the heat exchanger favors less fouling. Foulants suspended in the process fluids will deposit in low-velocity regions. Higher shear stress promotes dislodging of deposits from surfaces. Maintain relatively uniform velocities across the heat exchanger to reduce the incidence of sedimentation and accumulation of deposits.
Read the full article about fouling resistance.
Velocity and Hydrodynamic Effects
Hydrodynamic effects, such as flow velocity and shear stress at the surface, influence fouling. Within the pressure drop considerations, the higher the velocity, higher will be the thermal performance of the exchanger and less will be the fouling. Uniform and constant flow of process fluids past the heat exchanger favors less fouling. Foulants suspended in the process fluids will deposit in low-velocity regions. Higher shear stress promotes dislodging of deposits from surfaces. Maintain relatively uniform velocities across the heat exchanger to reduce the incidence of sedimentation and accumulation of deposits.
Read the full article about fouling resistance.
Parameters that influence fouling resistances
Many operational and design variables have been identified as having well-defined effect on fouling. One of those parameters is Fluid Temperature.
A good practical rule to follow is to expect more fouling as the temperature rises. This is due to a “baking on” effect, scaling tendencies, increased corrosion rate, faster reactions, crystal formation and polymerization, and loss in activity by some antifoulants.
Lower temperatures produce slower fouling buildup, and usually deposits that are easily removable. However, for some process fluids, low surface temperature promotes crystallization and solidification fouling. For those applications, it is better to use an optimum surface temperature to overcome these problems.
Biological fouling is a strong function of temperature. At higher temperatures, chemical and enzyme reactions proceed at a higher rate with a consequent increase in cell growth rate.
A good practical rule to follow is to expect more fouling as the temperature rises. This is due to a “baking on” effect, scaling tendencies, increased corrosion rate, faster reactions, crystal formation and polymerization, and loss in activity by some antifoulants.
Lower temperatures produce slower fouling buildup, and usually deposits that are easily removable. However, for some process fluids, low surface temperature promotes crystallization and solidification fouling. For those applications, it is better to use an optimum surface temperature to overcome these problems.
Biological fouling is a strong function of temperature. At higher temperatures, chemical and enzyme reactions proceed at a higher rate with a consequent increase in cell growth rate.
Heat Exchanger Fouling
Fouling is defined as the formation of undesired deposits on heat transfer surfaces, which increase the resistance to fluid flow, resulting in higher pressure drop and reduced heat transfer. The growth of deposits causes the thermohydraulic performance of heat exchanger to degrade over time. Fouling affects the energy consumption and therefore increases the amount of extra material or fuel required to generate the required amount of heat transfer.
Principles of Heat Transfer
To understand how heat losses occur and how they can be minimized needed to understand the principles of heat transfer. Heat transfer finds application in equipment sizing as well. For instance, a heat exchanger is used to transfer heat load from one fluid to another. Thus, heat transfer applications are involved with energy transfer in equipment, piping systems, and building design.
Heat transfer is determined by the effects of conduction, radiation and convection.
Conduction - heat transfer is based on one space surrendering heat while another one gains it by the ability of the dividing surface to conduct heat. Metals are the best conductors of heat, while wood, asbestos, and felt are the poorer ones.
Radiation - heat transfer is based on the properties of light, where no surface or fluid needed to carry heat from one object to another
Convection - heat transfer is based on the exchange of heat between a fluid, gas, or liquid as it transverses a conducting surface.
Heat transfer is determined by the effects of conduction, radiation and convection.
Conduction - heat transfer is based on one space surrendering heat while another one gains it by the ability of the dividing surface to conduct heat. Metals are the best conductors of heat, while wood, asbestos, and felt are the poorer ones.
Radiation - heat transfer is based on the properties of light, where no surface or fluid needed to carry heat from one object to another
Convection - heat transfer is based on the exchange of heat between a fluid, gas, or liquid as it transverses a conducting surface.
Wort Cooling Systems
Wort cooling systems are employed to bring the wort to a temperature suitable for fermentation. Closed systems with plate heat exchangers have been used for several decades to prevent the danger of infection and energy loss.
Wort cooling systems extract heat from the wort and generate hot water, brine, and propylene glycol solutions, as well as direct expansion of ammonia.
Wort coolers can be classified into: single stage (chilled water only) or multiple stage (ambient water, brine). Dimensions of the wort cooler depend on the amount of hot water required in the brewery for the needed fermentation temperature.
The cooling process is quite simple. Wort enters the heat exchanger and cools to a pitching temperature.
Heat exchangers require scheduled cleaning and proper maintenance for optimal heat transfer. The wort should be properly clarified before entering the cooler to reduce fouling.
Wort cooling systems extract heat from the wort and generate hot water, brine, and propylene glycol solutions, as well as direct expansion of ammonia.
Wort coolers can be classified into: single stage (chilled water only) or multiple stage (ambient water, brine). Dimensions of the wort cooler depend on the amount of hot water required in the brewery for the needed fermentation temperature.
The cooling process is quite simple. Wort enters the heat exchanger and cools to a pitching temperature.
Heat exchangers require scheduled cleaning and proper maintenance for optimal heat transfer. The wort should be properly clarified before entering the cooler to reduce fouling.
Pressure drop in heat exchangers
Fluids need to be pumped through the heat exchanger in most applications. It is essential to determine the fluid pumping power required as part of the system design and operating cost analysis.
The fluid pumping power is proportional to the fluid pressure drop, which is associated with fluid friction and other pressure drop contributions along the fluid flow path. The fluid pressure drop has a direct relationship with heat transfer, operation, size mechanical characteristics, and other factors including economic considerations.
The fluid pumping power is proportional to the fluid pressure drop, which is associated with fluid friction and other pressure drop contributions along the fluid flow path. The fluid pressure drop has a direct relationship with heat transfer, operation, size mechanical characteristics, and other factors including economic considerations.
Evolution of plate heat exchangers
Since the introduction in the 1920s for commercial usage plate-and-frame heat exchangers has evolved over the last several decades and various modifications were developed.
Some of these modifications were driven by new strategies for making more compact equipment, some focused on overcoming disadvantages of PHEs, others on expanding the applications spectrum. That resulted mostly in variations of corrugation patterns of plate’s surfaces and altered construction.
Brazed plate heat exchangers are the most compact type of heat exchangers available on a market today. And it is the most efficient one.
Brazed plate heat exchangers are made of a pack of thin corrugated plates that are brazed together to form a durable, self-contained unit. Brazing eliminates the need of frames and gaskets, and results in a unit able to withstand higher pressure and temperatures compared to PHEs. They are compact and lightweight due to absence of frames.
Typical applications of brazed plate heat exchangers include heating and cooling in the process industry, evaporation and condensation in refrigeration systems, and other HVAC installations.
Some of these modifications were driven by new strategies for making more compact equipment, some focused on overcoming disadvantages of PHEs, others on expanding the applications spectrum. That resulted mostly in variations of corrugation patterns of plate’s surfaces and altered construction.
Brazed plate heat exchangers are the most compact type of heat exchangers available on a market today. And it is the most efficient one.
Brazed plate heat exchangers are made of a pack of thin corrugated plates that are brazed together to form a durable, self-contained unit. Brazing eliminates the need of frames and gaskets, and results in a unit able to withstand higher pressure and temperatures compared to PHEs. They are compact and lightweight due to absence of frames.
Typical applications of brazed plate heat exchangers include heating and cooling in the process industry, evaporation and condensation in refrigeration systems, and other HVAC installations.
Classification of heat exchangers according to transfer process
There are 2 major categories:
1) Indirect contact type;
2) Direct contact type.
Indirect Contact Type Heat Exchangers
In this type of heat exchangers, the fluid streams remain separate, and the heat transfer takes place continuously through a separating wall. There is no direct mixing of the fluids because each fluid flows in separate fluid passages.
Direct Contact Type Heat Exchangers
In this type of heat exchangers, the two fluids are not separated by a wall. Here, closer temperature approaches are attained and the heat transfer process is also accompanied by a mass transfer.
1) Indirect contact type;
2) Direct contact type.
Indirect Contact Type Heat Exchangers
In this type of heat exchangers, the fluid streams remain separate, and the heat transfer takes place continuously through a separating wall. There is no direct mixing of the fluids because each fluid flows in separate fluid passages.
Direct Contact Type Heat Exchangers
In this type of heat exchangers, the two fluids are not separated by a wall. Here, closer temperature approaches are attained and the heat transfer process is also accompanied by a mass transfer.
Compact heat exchangers
Compact heat exchangers are used in a wide variety of applications. Typical among them are the heat exchangers used in air conditioning, beer and wort chilling, solar and geothermal systems, waste and process heat recovery. The need for light-weight, space-saving, and economical heat exchangers has driven the development of compact surfaces.
Specific characteristics of compact heat exchangers include the following:
- a high heat-transfer surface area per unit volume;
- fluids must be clean and relatively non-fouling because of relatively small flow passages and difficulty in cleaning;
- pressure drop consideration;
- operating pressures and temperatures are limited to a certain extent compared to shell and tube exchangers due to joining of the plates by brazing;
etc.
Subscribe to:
Posts (Atom)