Transcript
Heat Exchanger
What is a Heat Exchanger?
• It is a specially engineered device, permitting the transfer of heat from one fluid to another, without the mixing of two fluids.
• The exchanger transfers only the heat and not the fluid that carries it.
• The fluid medium may be a liquid or gas.
• A metal separator separates the two fluids, restricting them from mixing.
Flow arrangement in Heat Exchanger
1. Commonly, they are classified based on their flow arrangement.
2. These exchangers are divided into three primary categories, namely parallel, counter and cross – flow.
• In Parallel flow arrangement, the fluids (either liquids or moving gases) enter the exchanger from one end, moving parallel together to meet the other end.
• If the Counter – flow arrangement, the fluids enter the exchanger from the opposite ends.
• The fluids in the Cross – flow exchanger flow in a perpendicular pattern to each other.
• The Counter - flow arrangement is the most efficient, transporting maximum amount of heat from the fluid medium.
• Parallel arrangement of fluid allows uniform wall temperatures.
How does a heat exchanger work?1. A heat exchanger functions to
retrieve warm air from waste, deplete gases and liquids, to transfer it directly to a different medium, for reuse.
2. In the air to air heat exchanger, the humidity of the dirty air travels to the heat exchanger, to be transferred to the incoming fresh air.
3. Ducts, solid separators inside the device separate the incoming and outgoing air.
3. It is through this air – duct system that the dirty air is replaced by the same amount of fresh outside air.
4. Due to the existence of many ducts inside the device, the fresh air does not mix with the dirty air, though they cross the same path.
5. As a result, the heat of the warm air leaving your house meets the cold outside air entering inside.
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