You increase refrigerant flow (mass flow) by decreasing the capillary restriction and usually increasing the systems charge.

If you lower condensing pressure with the same capillary tube you will decrease mass flow and increase superheat.

Another way to lower superheat is to lower actual suction return.


Superheat at the suction port for a single molecule refrigerant or azeotrope is saturation temperature minus suction gas temperature. In a zeotropic blend superheat is the dew point (end of evaporation) minus suction gas temperature.

Either way as long as the return refrigerant isn't in saturation, lowering its temperature will obviously lower superheat. This is what superheat is, so i'm not sure what you think is happening....?

When you have very high superheat the mass flow is not enough to effectively cool the load you have, increasing mass flow will obviously increase suction pressure - but if you're only currently supplying enough refrigerant to evaporate the in first little bit of the evaporator, with the gas being heavilly superheated throughout the rest of the evaporator then you didn't have enough flow rate anyway.

In the end you've gained evaporator capacity at the lower temperature.

Sorry for taking this so off topic piotres

Tom