A transcritical R-744 refrigeration system, especially used for refrigerating a skating rink, has a heat exchanger between the gas cooler followed by a throttling device and the flash tank (or receiver), in order to eliminate the need of a flash-gas bypass. The heat exchanger connects to an external mechanical refrigeration system operating at a higher evaporating temperature than the transcritical R-744 refrigeration system, and generally totally condenses the vapor of the R-744 refrigerant before it reaches the flask tank. A method for improving the energy efficiency of the transcritical R-744 refrigeration system is also disclosed.

A heat-recovery-type refrigerating apparatus includes a compressor, a heat-source-side heat exchanger, and a plurality of usage-side heat exchangers, and refrigerant is sent from the usage-side heat exchanger functioning as a refrigerant radiator to the usage-side heat exchanger functioning as a refrigerant evaporator, whereby heat can be recovered between the usage-side heat exchangers. Here, a portion of the heat-source-side heat exchanger is configured as a precooling heat exchanger for always circulating high-pressure vapor refrigerant discharged from the compressor, and a refrigerant cooler for cooling an electrical equipment item is connected to a downstream side of the precooling heat exchanger.

An air conditioning system capable of treating a conditioned space by treating outdoor air from outside the conditioned space and treating air returned from inside the conditioned space, and mixing the outdoor air with the returned air to form supply air for the conditioned space, the air conditioning system including: •an outdoor air latent cooling treatment stage and a return air sensible cooling treatment stage, and •an air mixer for mixing outdoor air with return air to form the conditioned space supply air; wherein the outdoor air latent cooling treatment stage includes a dehumidification evaporator and the return air sensible cooling treatment stage includes a sensible evaporator, both evaporators being coupled to a direct expansion refrigeration circuit, and wherein the dehumidification evaporator thermal capacity is regulated in response to conditioned space humidity and the sensible evaporator thermal capacity is regulated in response to conditioned space dry bulb temperature.

A system includes a high side heat exchanger, a flash tank, a vessel, a load, and a compressor. The high side heat exchanger removes heat from a refrigerant. The flash tank stores the refrigerant from the high side heat exchanger. The vessel includes a chamber defined by an exterior housing and a tube positioned within the chamber. Heat is removed from the liquid refrigerant circulating through this tube and coming from the flash tank. The load uses the refrigerant from the tube to remove heat from a space proximate the load. The load sends the refrigerant into the chamber between the exterior housing and the tube. The compressor receives the refrigerant from the chamber between the exterior housing and the tube and compresses the refrigerant.

A system includes a high side heat exchanger, a flash tank, a vessel, a load, and a compressor. The high side heat exchanger removes heat from a refrigerant. The flash tank stores the refrigerant from the high side heat exchanger. The vessel includes a chamber defined by an exterior housing and a tube positioned within the chamber. Heat is removed from the liquid refrigerant circulating through this tube and coming from the flash tank. The load uses the refrigerant from the tube to remove heat from a space proximate the load. The load sends the refrigerant into the chamber between the exterior housing and the tube. The compressor receives the refrigerant from the chamber between the exterior housing and the tube and compresses the refrigerant.

Methods and systems for controlling working fluid flow in a heating, ventilation, air conditioning and refrigeration (HVACR) unit for an HVACR system are disclosed. The unit includes a compressor having a motor and a drive. The unit also includes a condenser fluidly connected to the compressor. A subcooler is located downstream of the condenser. The unit further includes an evaporator fluidly connected to the condenser. Also the unit includes a controller. The unit also includes a bypass assembly connected to the condenser. The bypass assembly includes a bypass flow control device and a bypass fluid line controlled by the bypass flow control device. When a heat recovery demand is detected by the controller, the controller is configured to open the bypass flow control device to allow a first portion of working fluid to bypass the condenser or the subcooler.

Methods and systems for controlling working fluid flow in a heating, ventilation, air conditioning and refrigeration (HVACR) unit for an HVACR system are disclosed. The unit includes a compressor having a motor and a drive. The unit also includes a condenser fluidly connected to the compressor. A subcooler is located downstream of the condenser. The unit further includes an evaporator fluidly connected to the condenser. Also the unit includes a controller. The unit also includes a bypass assembly connected to the condenser. The bypass assembly includes a bypass flow control device and a bypass fluid line controlled by the bypass flow control device. When a heat recovery demand is detected by the controller, the controller is configured to open the bypass flow control device to allow a first portion of working fluid to bypass the condenser or the subcooler.

A cycle enhancement apparatus is provided. The apparatus has a first side entrance line and exit line, both connected to a first side of a refrigerant line, and a second side entrance line and exit line, both connected to a second side of the refrigerant line. One-way valves prevent flow through the first side entrance line toward the first side, through the first side exit line away from the first side, through the second side entrance line toward the second side, and through the second side exit line away from the second side. The apparatus has a cycle enhancement line. The cycle enhancement line has an entrance portion, connected to the first side entrance line and the second side entrance line, an exit portion, connected to the first side exit line and the second side exit line, and a cycle enhancement between the entrance portion and the exit portion.

A cycle enhancement apparatus is provided. The apparatus has a first side entrance line and exit line, both connected to a first side of a refrigerant line, and a second side entrance line and exit line, both connected to a second side of the refrigerant line. One-way valves prevent flow through the first side entrance line toward the first side, through the first side exit line away from the first side, through the second side entrance line toward the second side, and through the second side exit line away from the second side. The apparatus has a cycle enhancement line. The cycle enhancement line has an entrance portion, connected to the first side entrance line and the second side entrance line, an exit portion, connected to the first side exit line and the second side exit line, and a cycle enhancement between the entrance portion and the exit portion.

An enhanced vapor injection air conditioning system (100) is provided and includes: a vapor injection compressor (1), a direction switching assembly (2), a first outdoor heat exchanger (3), a second outdoor heat exchanger (4) including first and second heat-exchange flow passages (41, 42), and an auxiliary electronic expansion valve assembly. A main electronic expansion valve assembly is connected between a first end (411) of the first heat-exchange flow passage and a second end (32) of the first outdoor heat exchanger. The auxiliary electronic expansion valve assembly has a first end connected with an inlet of the second heat-exchange flow passage (42), and a second end connected to a second end (412) of the first heat-exchange flow passage or between the main electronic expansion valve assembly and the first heat-exchange flow passage (41). A ratio DB of a sum of a caliber of the main electronic expansion valve assembly to that of the auxiliary electronic expansion valve assembly has a value range of 1≦DB≦7.