Provided is an air-conditioning apparatus configured so that a decrease in a refrigeration capacity can be suppressed without increasing the amount of refrigerant with which a refrigerant circuit is filled and that refrigerant can be suitably stored during a pump down operation. The air-conditioning apparatus includes a first on-off valve provided at a pipe between an expansion valve and a use side heat exchanger, a bypass branching from a pipe between the expansion valve and the first on-off valve and connected to a pipe at a suction-side of a compressor, and a refrigerant storage unit configured to store the refrigerant having passed through the bypass. In a pump down operation in which the compressor operates with the first on-off valve being in a closed state, the refrigerant having flowed out from the heat source side heat exchanger flows into the bypass, and then, is stored in the refrigerant storage unit.

A refrigeration system operable in cooling mode and defrosting mode is provided. The refrigeration system includes a defrost line connecting a first reservoir to an evaporation stage for conveying at least part of the flash gas from the first reservoir to the evaporation stage when the refrigeration system is operating in defrosting mode. The flash gas thereby releases heat in the evaporation stage for defrosting the evaporation stage. The refrigeration system can also include a discharge line connecting the evaporation stage to a second reservoir.

A liquid accumulator for a heat exchange system, includes a liquid accumulator housing provided with an air inlet, an air outlet, and a liquid inlet; and a cooling heat exchanger disposed in the liquid accumulator housing, wherein the cooling heat exchanger comprises an inlet end, a main body part, and an outlet end in sequence; the inlet end of the cooling heat exchanger is connected to the air inlet on the liquid accumulator housing; and the outlet end of the cooling heat exchanger is arranged to be higher than a working liquid level of a refrigerant in the liquid accumulator.

A two-stage refrigeration apparatus includes a high-stage refrigeration cycle including a high-stage-side refrigerant circuit including a high-stage-side compressor, high-stage-side condenser, high-stage-side expansion valve, and high-stage-side evaporator connected by pipes, a low-stage refrigeration cycle including a low-stage-side refrigerant circuit including a low-stage-side compressor, low-stage-side condenser, low-stage-side receiver, low-stage-side expansion valve, and low-stage-side evaporator connected by pipes, a cascade condenser including the high-stage-side evaporator and low-stage-side condenser, a receiver heat exchanging portion configured to cool the low-stage-side receiver, and a high-stage refrigeration cycle controller configured to perform controlling so as to activate the high-stage-side compressor when estimating a low-stage-side refrigerant will reach a supercritical state while the low-stage-side compressor is defrosted on the basis of the pressure of the low-stage-side refrigerant.

A refrigeration cycle apparatus is provided with a refrigerant circuit, a refrigerant tank circuit, and a degassing pipe. The refrigerant circuit is configured by connecting a compressor, a flow path switching apparatus, a first heat exchanger, a decompressing apparatus, and a second heat exchanger. The refrigerant tank circuit is connected to the first and second heat exchangers in parallel with the decompressing apparatus. The degassing pipe has a first end and a second end. The flow path switching apparatus is configured to switch a flow of refrigerant discharged from the compressor to any of the first and second heat exchangers. The refrigerant tank circuit contains a refrigerant tank. The degassing pipe has the first end connected to the refrigerant tank and has the second end connected to at least any of the refrigerant circuit and the refrigerant tank circuit.

A receiver assembly for a heat pump system is provided including a first receiver volume and a second receiver volume. The first receiver volume is configured to accommodate an amount of refrigerant based on a difference between a refrigerant charge for cooling operations of the heat pump system and a refrigerant charge for heating operations of the heat pump system. The second receiver volume has a first fluid connection configured to receive a hot gas injection and a second fluid connection. An expander is disposed along the second fluid connection. The receiver assembly further includes a fluid line configured to connect the first receiver volume and the second receiver volume and a controllable valve configured to regulate flow between the first receiver volume and the second receiver volume disposed along the fluid line.

A system for maximizing the measured efficiency of an HVAC&R system including two pressure sensors, two temperature sensors, a flow sensor, a power voltage sensor, a power current sensor, and a controller. Each pressure sensor may be adapted to measure different refrigerant pressures and generate respective pressure signals. Each temperature sensor may be adapted to measure different refrigerant temperatures and generate respective temperature signals. The flow sensor may be adapted to measure a refrigerant flow rate and to generate a flow signal. The power voltage sensor may be configured to measure an electrical voltage input and generate a power voltage signal. The power current sensor configured to measure an electrical current input and to generate a power current signal. The controller may be adapted to receive the signals, calculate a measured efficiency, and output a first voltage output signal having a value dependent upon the measured efficiency.

A system for maximizing the measured efficiency of an HVAC&R system may include the steps of (1) providing a plurality of operating parameters selected from the group consisting of condenser fan speed, evaporator fan speed, inlet solenoid valve position, outlet solenoid valve position, and compressor control to the air conditioner or the heat pump system wherein each of the plurality of operating parameters has a respective operating parameter value; (2) calculating an initial efficiency of the system using signals received from a plurality of components selected from the group consisting of a temperature sensor, a humidity sensor, a pressure sensor, a flow sensor, a voltage sensor, and a current sensor; and (3) proceeding, starting with a first of the plurality of operating parameters, to iteratively adjust values of each of the plurality of operating parameters and accept the new values only if the measured efficiency increases.

The invention presents air-conditioning system with chiller that provides, when operated in the cooling mode, cooling hardware for conditioning space and a heat exchanger for cooling and dehumidification of ambient air in supply air stream with cold liquid. In addition, the invention offers a method and design of a heat utilization system. The method incorporates refrigeration cycle with two consecutive expansions, two expansion devices, and a heat exchanger operating as a second condenser. The method can be used for air conditioners and chillers reheating over-chilled for dehumidification indoor and supply air. The method and design allow energy efficient heat utilization with variable amount of utilized heat.

A dynamic method of maintaining a predefined sub-cooling of a refrigerant exiting a condenser by dynamic control of the circulating mass of refrigerant, by transferring the refrigerant into or towards a receiver installed in parallel with the liquid connection between the condenser and the expansion valve, as a function of the difference in temperatures between the condensation temperature of the saturation liquid and the discharge temperature from the condenser.