A multi-parallel carbon dioxide heat pump control method based on target load control, wherein the multi-parallel carbon dioxide heat pump comprises a carbon dioxide circulation loop, a heat source pipeline and a hot water pipeline, and the control method comprises: adjusting the opening degree of an electronic expansion valve (3) according to the temperature of an inlet of the hot water pipeline, the temperature of an outlet of the hot water pipeline, the flow in the hot water pipeline and a target outlet temperature set by a user, such that the steady-state change of system pressure can be realized by adjusting the electronic expansion valve (3) on the basis of the fluctuation of parameters such as user side temperature and flow, thus a target outlet temperature change curve is rapidly and stably converged to a target value, and the outlet temperature can be rapidly stabilized.

In a first fluid circulation device, a heat exchanger, a tank that stores a first fluid liquefied by the heat exchanger, a first fluid pump that pumps the first fluid stored in the tank, a heater that heats the first fluid pumped from the first fluid pump, and a first fluid supply unit to which the first fluid is supplied from the heater are connected by a first pipe. A second fluid circulation device includes a cooler that cools a second fluid, causes the second fluid having been cooled by the cooler to circulate through a second pipe, and returns the second fluid to the cooler. The second pipe is connected to the heat exchanger and is connected to the tank and the first fluid pump, and the second fluid cools the first fluid in the heat exchanger, the tank, and the first fluid pump.

According to various embodiments of the invention, a heat exchanger can have at least one duct for conveying a coolant, wherein the at least one duct has a first section and a second section, the first section being arranged in the at least one duct upstream relative to the second section, in relation to a flow direction of the coolant, the second section having a cross section area that is larger than a cross section area of the first section, such that a sublimation of the coolant in the second section is made possible.

A multistage compression system uses refrigerant and oil. The multistage compression system includes a low-stage compressor that compresses the refrigerant, a high-stage compressor that further compresses the refrigerant compressed by the low-stage compressor, refrigerant pipes that introduce the refrigerant compressed and discharged by the low-stage compressor into a suction part of the high-stage compressor, an intercooler, and an oil discharge pipe. The intercooler cools the refrigerant discharged by the low-stage compressor before the refrigerant is sucked into the high-stage compressor. The intercooler is disposed between the refrigerant pipes. The oil discharge pipe discharges the oil in the low-stage compressor. The oil discharge pipe connects the low-stage compressor and a portion of the refrigerant pipes. The portion of the refrigerant pipes is on an upstream side of the intercooler.

An air conditioner includes an ejector that raises a pressure of refrigerant by using energy for refrigerant decompression and expansion. A switching mechanism switches between a refrigerant flow in a first operation and a refrigerant flow in a second operation. The air conditioner is configured such that in the first operation, refrigerant compressed by a compression mechanism radiates heat in a use-side heat exchanger and is decompressed and expanded by the ejector while refrigerant evaporated in a heat-source-side heat exchanger is raised in pressure by the ejector. The air conditioner is configured such that in the second operation, refrigerant compressed by the compression mechanism radiates heat in the heat-source-side heat exchanger and is decompressed and expanded by a first expansion valve before being evaporated in the use-side heat exchanger while refrigerant does not flow through the ejector.

The present disclosure relates to the technical field of heat pumps, in particular to an air source CO.sub.2 heat pump system for preventing an evaporator from frosting by using heat of a heat regenerator. The air source CO.sub.2 heat pump system mainly includes an air source heat pump system, a regenerative heat exchange tank and a cooling pump. Through the regenerative heat exchange tank, on the one hand, the temperature drop of regenerative heat of the system is further increased and throttling loss is reduced; on the other hand, the heat generated by the regenerative temperature drop is configured for heat storage used for defrosting, and configured for overheating temperature rise.

A refrigeration system includes a rotary pressure exchanger fluidly coupled to a low pressure branch and a high pressure branch. The rotary pressure exchanger is configured to receive the refrigerant at high pressure from the high pressure branch, to receive the refrigerant at low pressure from the low pressure branch, and to exchange pressure between the refrigerant at high pressure and the refrigerant at low pressure, and wherein a first exiting stream from the rotary pressure exchanger includes the refrigerant at high pressure in the supercritical state or the subcritical state and a second exiting stream from the rotary pressure exchanger includes the refrigerant at low pressure in the liquid state or the two-phase mixture of liquid and vapor.

A refrigerant circuit of a refrigeration apparatus performs a refrigeration cycle in which a high pressure is equal to or greater than the critical pressure of a refrigerant. The refrigeration apparatus performs at least a heat application operation in which an indoor heat exchanger of the refrigerant circuit functions as a radiator. A controller of the refrigeration apparatus controls the opening degree of the indoor expansion valve of the refrigerant circuit so that the temperature of the refrigerant at the outlet of the indoor heat exchanger reaches a predetermined reference temperature, in the heat application operation.

The disclosure provides a heat pump cycle that allows for an improved matching of the T(Q) slopes of the heat pump cycle. More particularly, the high temperature heat exchange is separated into two stages. Furthermore, a portion of the working fluid that was cooled in the first stage, is further cooled by expansion before being mixed with a heated working fluid for input to the recuperating heat exchanger.

A system has a first compressor and a second compressor. A heat rejection heat exchanger is coupled to the first and second compressors to receive refrigerant compressed by the compressors. The system includes an economizer for receiving refrigerant from the heat rejection heat exchanger and reducing an enthalpy of a first portion of the received refrigerant while increasing an enthalpy of a second portion. The second portion is returned to the compressor. The ejector has a primary inlet coupled to the means to receive a first flow of the reduced enthalpy refrigerant. The ejector has a secondary inlet and an outlet. The outlet is coupled to the first compressor to return refrigerant to the first compressor. A first heat absorption heat exchanger is coupled to the economizer to receive a second flow of the reduced enthalpy refrigerant and is upstream of the secondary inlet of the ejector. A second heat absorption heat exchanger is between the outlet of the ejector and the first compressor.