Direct expansion coil or DX coil is Yehjeh’s most important production. Compared with water coils, not only more difficult process , it requires more complicated copper fittings brazing and circuit design, more high-levels inspection standards. The quality and stability of products also need to be higher level to prevent leakage of filled refrigerant.
In direct expansion system, there is possibility of refrigerant leakage for long distances, and the cost of the refrigerant would be high. Also the pressure drop in the line would decrease evaporator coefficient of performance and efficiency.The direct expansion coil is preferred for air conditioning purposes, where the evaporator is very near to the compressors. This is direct method of cooling the substance and, therefore quite efficient.
Advantages of Direct Expansion System: low installation costs, ease to adjust and balance the system, minimum ceiling or wall space needed, low energy consumption, low maintenance costs. individual section can be operated without running the entire system in the building, comfort under varying load conditions and good relative humidity control.