US Patent 9234685 Methods and systems to increase evaporator capacity

Embodiments to increase the capacity of the evaporator of a vapor-compression refrigeration system are described. The refrigeration system may be configured to have a first stage suction line heat exchanger and a second stage suction line heat exchanger. The refrigerant exiting the evaporator can be heated by the first heat exchanger. A thermal bulb of an expansion device, such as a thermostatic expansion valve (TXV) can be positioned downstream of the first heat exchanger. The thermal bulb is capable of regulating a variable volume of refrigerant through the expansion device in response to temperature changes. Thus, the superheat refrigerant vapor region in the evaporator can be reduced, thereby increasing the efficiency of the refrigeration system. The refrigerant exiting the evaporator is a liquid/vapor refrigerant mixture. The mixture can be vaporized to a refrigerant vapor in the first heat exchanger.