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When you put your pot on the stove element, the heat from the element is exchanged to the pot, and then to the liquid in it.
The refrigerator in your home has a heat exchanger usually located on the outside back wall of the cabinet. The heat that is being pumped out of your fridge travels through the intricate web of lines on the back of the cabinet, and with the abundance of surface area available to the cooler kitchen air, heat from within your fridge is ‘exchanged’ with the cooler air surrounding the lines.
The radiator in your car is a heat exchanger. The hot coolant from your engine is pumped through the lines in the radiator, and as air passes through and around the ‘fins’ of the rad, heat is exchanged, the liquid within the lines of the rad is cooled, and is ready to go back to your engine to pick up more heat. And of course, the coolant ‘heat exchanges’ within the engine block to cool the block down.
Heat exchangers are everywhere and there are many different kinds.
In our case, the ‘fluid’ we are concerned with is the compressed air exiting our compressor receiver, heading for the plant air mains. The other fluid is the water surrounding the air line which is there to effect heat exchange.
The heat exchanger referred to here is a water jacket type.
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The hot compressed air from the receiver is still carrying lots of water in vapour form. Click here to find out why there is water in your compressed air and the receiver.
If we don’t lower the compressed air temperature down past the dew point right here, before the air gets to the mains and the drop lines, then the compressed air will de-water in the lines, creating free water there instead. This is not good!
If you haven’t see what problems can occur with water in your compressed air lines, visit this link.
In the water jacket heat exchanger, the two fluids (compressed air and cool water) will be separated by the metal pipe of the air line.
Cold water will flow around the air pipe, and heat exchange will take place.
The aim of this heat exchanger is to make sure that the surface area of exchanger is large enough – or the ‘dwell time’ of the two fluids in the exchanger is long enough, for the required amount of heat to be transferred from the hot compressed air to the cold water.
Things you’ll need to know to help determine the size of your heat exchanger are:
With this information, your heat exchanger vendor should be able to help you determine the size you need.
If you wish more details on the science of heat exchanging, look up the following topics in the search box below:
“The first law of thermodynamics”
“Fourier’s law of conduction”
“Newton’s law of cooling”
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