Hi, I am a R&D engineer at a technical refrigeration firm. The firm decided to use hot-gas defrost system in commercial cabinets. In our system we have a suction line heat exchanger (now only heat heat exchanger). In normal refrigeration loop, the gas which comes from evaporator, enters the heat exchanger and it warms. After that, it enters accumulator, then it reaches the compressor. On the other hand, the liquid(maybe liquid-gas mixture) which comes from condenser, enters the heat exchanger that return gas enters the evaporator. Now we expect, when the liquid cools, the return gas warms. Our goal,we should obtain both subcooling and superheating. However, as the superheating is really high, subcooling is almost never. our subcooling is only 0.5 degree celcius, our superheating is 30 degree celcius. What is the problem. Our fluid is R404a, and 1 kg refrigerant is in our system. Is the refrigerant sufficient?