Evaporator Shell and Tube Heat

Exchanger for Rooftop Air Conditioning Unit

Dry evaporator for freon refrigeration system. In this evaporator, the filling amount of the refrigerant liquid

is small, which is about 35% to 40% of the internal volume of the pipe group, and the refrigerant does not

have a free liquid surface during the vaporization process. It is widely used in refrigeration and air

conditioning, there is the replacement of full-liquid evaporator development trend. According to the

arrangement of the tube in the shell can be divided into straight tube and U-tube two.

Straight tube dry evaporator. Its structure and full-liquid evaporator similar, the difference is in a number

of horizontal smooth copper tube with a number of blocks on the reverse arrangement of the cut arc of the

circular baffle area, the more important is the work process is completely different. In a dry evaporator, the

liquid of the refrigerant evaporates in the tube while the liquid refrigerant (water or brine) is cooled outside

the tube.

The liquid freon is decompressed by the throttle valve and enters the tube from the lower end of the cap.

With the flow in the tube, the absorption tube of water or brine heat, liquid freon gradually vaporized, the

steam from the top cover to take over the return to the compressor. As long as the tube freon flow rate is

greater than a certain value, you can ensure that the smooth return of lubricants compressor. Dry

evaporators are generally made of steel pipe, can use light pipe, can also be used with longitudinal fins of

the finned tube. The use of light tube when the heat transfer coefficient is small, the number of processes.

With the inner fin tube when the heat transfer coefficient is large, the number of processes can be

reduced. However, the light pipe is easier and cheaper than the inner finned tube. In particular, in recent

years, the heat pipe's heat transfer coefficient is close to the heat transfer coefficient of the inner fin tube.