How Does Coaxial Heat Exchanger Work?

What is a coaxial heat exchanger?

A coaxial heat exchanger is a kind kind of tube heat exchanger, it is usually used as condenser or evaporator  in a heat pump, marine air conditioner, swimming pool, water chiller etc. Mostly it is a water cold heat exchanger. The structure can be as round, rectangle, spiral, double helix and so on.

The structure of coaxial heat exchanger

The coaxial heat exchanger is designed as a "tube in tube" structure. Usually the outer tube is made of steel/copper, and the inner tube can be titanium, copper, copper-nickel depending on the requirements of working condition.  For the inner tube is has many spiral grooves on the surface, which will enlarge the connection surface and get more heat transferred.

How does the heat exchange in the coaxial heat exchanger?

Mostly water flow  in the inner tube and refrigeration flow between the outer & inner tube(refrigeration loop). The temperature of refrigeration and water are different, so heat will transfer from one with high temperature to the other one. The mostly it is counterflow.

Above is a kind of coaxial heat exchanger from HZSS. The water flow into the inner tube from bottom and flow out from the top. Refrigeration gas will flow into the refrigeration loop from the copper tube whose diameter is large, and refrigeration liquid flow out from the small diameter one.