An air cooled heat exchanger is a sub device which acts as a pressure vessel and is used for cooling a circulating fluid by rejecting heat from it. Further, this circulating cooled liquid absorbs the heat from the surroundings and lowers down the temperature. This type of heat exchanger is used in air conditioning systems and refrigeration system. It exists not only in big sizes but small size as well. For example: radiator used in the cars is also a type of the air cooled heat exchanger.
The air which is cooled by this type of heat exchanger is called as dry cooling because it does not require cool water supply, which is also an advantage. One unit can exist in very large sizes, such that it can act as condensation unit for a turbine exhaust. This big unit consists of two big fans of diameter 60 feet which are able to move by 500 horsepower motors.
There are wide spread applications and advantages of air cooled heat exchangers (air to water heat exchangers) which includes, generally all HVAC industries, engine cooling system of automobiles, condensing the gases, in cooling the reactors in power plants, in steam condensers, in hospitals, and in refineries industries.
Find Local A/C & Heating Contractors at http://hvac.networx.com/ – FREE Heating & Air Conditioning Quotes.
Fundamental principle of an air to water heat exchangers is the well known Newton’s law of cooling which is “To lower down the temperature of a body, extract the heat from it.” It generally contains some tubes which are filled with some specific fluid i.e. liquid or gas, which plays the role of heat transfer from one media to another.
One unit of air to water heat exchangers contains many components but the construction of this unit is not complex. These components include header, tubes successions, fan, nozzle, plenum, fan ring, column support, cove bell and a driving system for fans. Motors are used for driving the fan in air to water heat exchangers. Size of the fan is related to the power of motor, high power motor will be required for driving the fan with a bigger diameter.
The tubes used in air to water heat exchangers are the basic parts; these tubes have to resist high pressure and low temperature depending upon the type of tube. They are made up of materials like metal alloy, such as aluminum steel with high carbon concentration, brass and stainless steel. The standard size of these tubes is one inch of diameter.
Headers play a vital role in construction, they are the boxes connected with tubes and these boxes circulate the cooled fluid in the tubes. Further headers are of many types like cover plate and bonnet headers. These are made up of materials like stainless steel and exotic alloys as aluminum.
There exist many types of air to water heat exchangers. Few of them are plate, plate fin, shell and tube type air to water heat exchangers. Every type of air to water heat exchangers has its own working efficiency depending upon the construction. And the most important point to mention here is that a good regular maintenance is required in all types of air cooled heat exchangers. The compressors fitted in these heat exchangers can blast due to steep fluctuations in pressures, which can be hazardous. So, a proper control for these devices is required.
