A system has a compressor, a heat rejection heat exchanger, first and second ejectors, first and second heat absorption heat exchangers, and a separator. The ejectors each have a primary inlet coupled to the heat rejection exchanger to receive refrigerant. A second heat absorption heat exchanger is coupled to the outlet of the second ejector to receive refrigerant. The separator has an inlet coupled to the outlet of the first ejector to receive refrigerant from the first ejector. The separator has a gas outlet coupled to the secondary inlet of the second ejector to deliver refrigerant to the second ejector. The separator has a liquid outlet coupled to the secondary inlet of the first ejector via the first heat absorption heat exchanger to deliver refrigerant to the first ejector.

A centrifugal chiller in which a closed-cycle refrigeration cycle is formed by connecting a compressor, a condenser, an economizer and decompression means forming a multi-stage compression cycle, and an evaporator, with the refrigeration cycle being charged with a low-pressure refrigerant. The condenser and the economizer are integrated with each other by having a portion of their vessel walls form a shared wall, with the base surface of the economizer being positioned below the base surface of the condenser and above the base surface of the evaporator.

Disclosed is a valve, an expansion valve and their stepping control methods. The valve includes a valve body, a limiting unit, and a heating unit installed in the limiting unit. The valve body has an actuation space, and a first through hole and a second through hole communicated with the actuation space, and the actuation space further contains a valve seat disposed between the first and second through holes, and the limiting unit is installed in the actuation space, and a variable spacing is defined between the limiting unit and the valve seat. When the variable spacing is reduced, the heating unit heats up the interior of the limiting unit for heating to prevent ice buildups, so as to maintain a flowing state of the variable spacing.

An air conditioner is provided. The air conditioner includes a heat pump cycle channel in which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected with one another in sequence. A resistance channel is disposed between an outlet of the compressor and the outdoor heat exchanger to increase pressure of refrigerant flowing from the outlet to the outdoor heat exchanger.

Embodiments relate generally to subcooling control of a heating, ventilation, and air conditioning (HVAC) system. An HVAC system may include a compressor, a first heat exchanger, a refrigerant vessel having an inlet fluidly coupled to a discharge conduit extending from the compressor, and the refrigerant vessel having an outlet fluidly coupled to a liquid conduit, the liquid conduit configured to pass liquid refrigerant between the first heat exchanger and a second heat exchanger. The HVAC system may further include an electronic expansion valve (EEV) fluidly coupled between the discharge conduit and the inlet of the refrigerant vessel, wherein the EEV is configured to modulate and divert a portion of vapor refrigerant flowing through the discharge conduit into the refrigerant vessel to control subcooling (SC) produced by the HVAC system.

The present invention provides a system and method for an improved multistage, cascade refrigeration system using hot gas defrost to rid the evaporator of ice build-up which accumulates over time, while the air in the evaporator enclosure remains below the freezing point of water. The present invention thus provides greater defrost flexibility with increased ease of design and implementation than current refrigeration systems, which allows for more robust hot gas defrost function for multistage refrigeration systems, such that it is unaffected by temperature changes of the condensing fluid (ambient air temperature for air cooled condensers, water temperature for water cooled condensers), and can be readily adapted to any refrigerant suitable for a selected temperature range.

A heat pump system including a charge compensator having a liquid line port for an inflow of a refrigerant into the charge compensator and for an outflow of the refrigerant from the charge compensator. The heat pump system further includes an isolation valve configured to control flows of the refrigerant to and from the charge compensator through a liquid line piping of the heat pump system based on whether the heat pump system is operating in a cooling mode, a defrost mode, or a heating mode, where the liquid line port is fluidly coupled to the liquid line piping of the heat pump system.

A two temperature electronic expansion valve control for variable speed compressors that utilizes a correlation between airflow percentage and heat exchanger pressure drop to control the operation of an expansion valve. An indoor airflow percentage request may be communicated from an outdoor controller to an air handler controller. Using a correlation between airflow percentage and pressure drop across the heat exchanger, the airflow percentage may be used in predicting an outlet pressure of refrigerant exhausted from the heat exchanger. The predicted pressure drop may be used in determining a saturated temperature for the exhausted refrigerant. The determined saturated temperature may be compared to a sensed temperature of the refrigerant at the outlet of the heat exchanger to determine a superheat value, which is compared to a reference superheat value in determining the degree to open or close the expansion valve.

A refrigeration apparatus (1) includes a main refrigerant circuit (2) including a positive displacement compressor (4), a condenser (6), an expansion valve (8), and an evaporator (10), through which a refrigerant circulates successively in a closed loop circulation, a lubrication refrigerant line (18) connected to the main refrigerant circuit (2) between the condenser (6) and the expansion valve (8) or to the condenser (6), in which circulates a portion of the refrigerant of the main refrigerant circuit (2) and connected to the compressor (4) for lubrication of said compressor (4) with the refrigerant. The lubrication refrigerant line (18) includes, upstream from the compressor (4): a throttle valve (20) adapted to vary the lubrication refrigerant flow entering the compressor (4), a downstream pressure detector (30) configured to measure refrigerant pressure (P3) downstream the throttle valve (20) and upstream the compressor (4).

The present invention relates to a low-power absorption refrigeration machine that enables the use of air as a refrigerant and has an evaporation unit that is separated from the rest of the absorption refrigeration machine and works with LiBr/H.sub.2O, H.sub.2O/NH.sub.3, LiNO.sub.3/NH.sub.3 or similar solutions, configuring an air-air machine wherein cold is produced directly in the enclosure to be air conditioned without need for impeller pumps and fan coils.