333results about "Subcoolers" patented technology

The invention relates to a heat pump device that makes it possible to utilize waste heat from technical processes or from the environment to simultaneously generate useful steam (12) and useful heat. The heat pump device comprises a heat pump module (1), a low-pressure steam generator (2) for generating low-pressure steam (11), a steam jet compressor (3) for generating useful steam (12) from high-pressure steam (10) and the low-pressure steam (11), and a first heat exchanger (4) for providing the useful heat. The heat pump device is suitable for applications where there is a simultaneous demand for both steam and heat.

The utility model provides a stand-alone system air suspension frequency conversion centrifugal water chilling unit which comprises a circulation main loop formed by connecting an evaporator, an air suspension centrifugal compressor, a condenser and an economizer through refrigerant pipelines so as to form a refrigeration circulation loop; wherein throttling pipelines are respectively arranged on a refrigerant pipeline between the condenser and the economizer and a refrigerant pipeline between the economizer and the evaporator, so that secondary throttling is carried out on a liquid refrigerant in the refrigerant pipelines; one end of the air supply pipeline is communicated with the economizer, and the other end of the air supply pipeline is communicated with the air suspension centrifugal compressor; the variable-frequency cooling pipeline comprises a frequency converter, one end of the frequency converter is communicated with the condenser through a frequency converter cooling liquid inlet pipeline, and the other end of the frequency converter is communicated with the evaporator through a frequency converter cooling air return pipeline. The unit provided by the utility model can effectively improve the refrigeration efficiency and performance, and reduce the energy consumption and operation cost, thereby realizing the efficient, energy-saving and environment-friendly refrigeration effect.

The present application discloses a condenser, comprising a housing, at least one liquid guide plate layer, a condenser tube bundle, a supercooling channel, and a supercooling tube bundle. The liquid guide plate layer is configured to guide refrigerant liquid obtained by condensation of the condenser tube bundle on the upper part of the liquid guide plate layer into the supercooling channel, so as to exchange, in the supercooling channel, heat with a cooling medium in the supercooling tube bundle. According to the condenser of the present application, the supercooling channel is directly provided in the condenser, and at least some of the supercooling tube bundles are directly provided in the supercooling channel, so that the number of the supercooling tube bundles at the bottom of the housing is reduced, thereby lowering the liquid refrigerant height required for immersing the supercooling tube bundles at the bottom of the housing, and thus reducing the refrigerant charge required for the condenser.

Provided are a heat exchange component (1) and a heating and cooling control device (1000). The heat exchange component comprises a heat exchanger (11) and an external assembly, wherein a first flow channel (111) and a second flow channel (112), which are independent of each other, are provided in the heat exchanger (11); and the external assembly is mounted on the heat exchanger (11), and comprises a communication device (13) and a throttling device (12). The communication device (13) comprises a first connection port (1321), a second connection port (1322) and a third connection port (1323), every two of which are in communication with each another, wherein the first connection port (1321) is in communication with the first flow channel (111), and the second connection port (1322) is in communication with the second flow channel (112) by means of the throttling device (12).

The present disclosure provides a multi-split air conditioning system and a control method thereof, comprising a compressor, an outdoor heat exchanger, a first gas side pipe, a second gas side pipe and a liquid side pipe, the first gas side pipe, the second gas side pipe and the liquid side pipe are all communicated between the indoor side and the outdoor side, and the first gas side pipe is communicated with the exhaust end of the compressor; further comprising at least one indoor unit, at least one heat storage module, at least one constant temperature dehumidification indoor unit, at least one hot water module, at least one floor heating module, and a photovoltaic module capable of absorbing solar energy and generating electric energy for supply to the multi-split air conditioning system. According to the present disclosure, the effects of constant temperature dehumidification, heat storage defrosting, air conditioning demand, floor heating demand, domestic hot water demand and photovoltaic application can be realized simultaneously through a set of system, the actual needs of users are solved, and each module can be selected to be connected to the system or not according to actual needs.

The invention relates to the technical field of refrigerating systems, and discloses a single-machine double-system type hot fluorine defrosting refrigerating system which comprises a main machine refrigerating system, an auxiliary machine refrigerating system and two gas-liquid separators, the main machine refrigerating system comprises a first-stage compressor, a first-stage condenser, a first-stage expansion valve and a first-stage evaporator, and the auxiliary machine refrigerating system comprises a second-stage compressor, a second-stage condenser, a second-stage expansion valve and a second-stage evaporator; the auxiliary machine refrigeration system comprises a second-stage compressor, a second-stage condenser, a second-stage expansion valve, a second-stage evaporator, a third-stage condenser, a third-stage expansion valve and a third-stage evaporator. According to the technical scheme, the double refrigeration circulation paths are introduced into the refrigeration system, during refrigeration, the main machine refrigeration system is responsible for refrigeration, the auxiliary machine refrigeration system supplies liquid to the main machine refrigeration system for undercooling, the heat load is relieved, and the unit refrigeration capacity is improved; in the defrosting process, the auxiliary machine refrigeration system is adopted for generating high-temperature and high-pressure hot fluorine for defrosting, the energy consumption of hot defrosting is reduced, fire hazards caused by aging of electric heating elements are avoided, and the safety coefficient of system operation is improved.

The utility model discloses a supercooling integrated gas-liquid separator which belongs to the technical field of air conditioners and comprises a tank body, an air inlet pipe and an air outlet pipe, the top of the tank body is connected with the air outlet pipe and the air inlet pipe, one end of the air outlet pipe and one end of the air inlet pipe are both located inside the tank body, the other end of the air outlet pipe and the other end of the air inlet pipe are both located outside the tank body, and a supercooling double pipe and an auxiliary path inlet pipe are arranged in the tank body. The upper portion of the supercooling double pipe is connected with the upper portion of the auxiliary path inlet pipe through a tee joint, and the lower portion of the supercooling double pipe is connected with the lower portion of the auxiliary path inlet pipe through an electronic expansion valve. The supercooling coil is arranged in the gas-liquid separator, the supercooling function and the gas-liquid separation function are integrated into the gas-liquid separator, the space of the tank body is fully utilized, secondary heat exchange of a high-pressure side refrigerant and a low-pressure side refrigerant is achieved, the supercooling degree of the high-pressure side refrigerant is increased, the superheat degree of the low-pressure side refrigerant is improved, and the system performance is improved.

According to the efficient steam heat pump system with the subcooler and the control method, the outlet end of a compressor is connected with the inlet end of a condenser, the outlet end of the condenser is connected with a refrigerant inlet of the subcooler through a liquid storage device, and a refrigerant outlet of the subcooler is connected with an inlet of an evaporator through an electronic expansion valve; the evaporator outlet is connected with the inlet end of the compressor; the flow of cold water entering the subcooler is controlled through the proportional three-way adjusting valve, the water outlet end of the subcooler is connected with the water inlet end of the condenser, the flow of the cold water entering the condenser is adjusted through the flow adjusting valve, and redundant flow enters the redundant heat storage box through the electric valve. The supercooler and the redundant heat storage box are additionally arranged, so that the supercooling degree of a refrigerant is accurately controlled, the system efficiency is improved, the comprehensive utilization rate of energy can be effectively improved, and the system operation cost is reduced.

A system includes a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The system further includes a first gas cooler, configured to provide working fluid to a first inlet of a heat exchanger and a second inlet of a heat exchanger. The heat exchanger is configured to exchange heat between fluid provided via the first inlet and fluid provided via the second inlet. A first outlet of the heat exchanger provides the first fluid to the PX. A second outlet of the heat exchanger provides the second fluid to the PX. The system further includes a receiver, configured to receive the first fluid and the second fluid from the PX. The system further includes a first compressor, configured to provide working fluid to the first gas cooler.

Systems and methods for regenerative ejector-based cooling cycles that utilize an ejector as the motivating force in a cooling loop to regeneratively sub-cool a refrigerant in a single-stage cooling cycle.

A vapour compression refrigeration system has a main refrigerant circuit having a main gas cooler or condenser arranged in a high pressure branch, a first main evaporator arranged in a first low pressure branch, a main compressor fluidically connecting the first low pressure branch to the high pressure branch, and an expansion device connecting the high pressure branch to an intermediate pressure branch. The system has a by-pass branch connecting the high-pressure branch to the intermediate pressure branch and provided with a by-pass valve, a secondary refrigerant circuit having a secondary gas cooler or condenser arranged in a secondary high pressure branch, a secondary evaporator arranged in a secondary low pressure branch, and a secondary expansion device connecting the secondary high pressure branch to the secondary low pressure branch. A rotary pressure exchanger is fluidically connected to the by-pass branch downstream of the by-pass valve and the secondary refrigerant circuit.

The invention discloses a subcooler and a deep subcooler for a refrigerating system and a control method of the subcooler and the deep subcooler, and belongs to the technical field of refrigeration. The deep subcooler comprises a subcooling heat exchange unit, an independent cold source loop and a pressure control valve; the supercooling heat exchange unit is connected between the high-pressure liquid reservoir and the throttling device in series, and the primary liquid refrigerant is deeply cooled to be equal to or close to the target value of the evaporation temperature through low-temperature cooling capacity provided by a low-pressure evaporation system or an independent cold source loop. The independent cold source is driven by a compressor with the minimum refrigerating capacity in the system, and an air return pipeline of the independent cold source is bridged with air return pipelines of other compressors of the system through an outlet pressure balance valve, so that the surplus refrigerating capacity is fully utilized. The evaporation pressure of a cold source loop is changed by monitoring the supercooled liquid temperature and feeding back and adjusting the opening degree of a pressure control valve, precise closed-loop control over the supercooled temperature is achieved, throttling flash gas can be remarkably reduced or even eliminated, the effective refrigerating capacity of unit refrigerant and the heat exchange efficiency of an evaporator are improved, and the system energy efficiency is greatly improved.

The application provides a control method, a control device and a heat pump system, and the control method comprises the following steps: obtaining the exhaust temperature of a compressor; determining whether the exhaust temperature of the compressor meets a first set temperature condition; obtaining the supercooling degree of the economizer; and adjusting the main electronic expansion valve and / or the auxiliary electronic expansion valve according to the interval range of the supercooling degree of the economizer. The application provides a control method, a control device and a heat pump system, and the supercooling degree of the economizer is detected and determined when the exhaust temperature is too high and needs to be inhibited, the supercooling degree of the economizer is detected, the auxiliary valve is adjusted while the main valve is closed, the supercooling degree of the economizer is increased, the air supplement is increased, and the exhaust temperature is reduced.

This refrigerator is provided with a refrigeration cycle, a sensor, and a control device. The refrigeration cycle has a circulation line, a first compression part, a middle stage part, a second compression part, an injection pipe, a supercooling heat exchanger, a supercooling expansion valve, a main expansion valve, an evaporator, a bypass pipe, and a bypass valve. The control device has: an acquisition part for acquiring a physical quantity related to the refrigeration cycle; a determination part for determining whether or not a supercooling degree of a refrigerant of the circulation line having passed through the supercooling heat exchanger is lower than a target value, on the basis of the physical quantity related to the refrigeration cycle; and a valve control part for controlling the bypass valve to open the bypass pipe, when the supercooling degree of the refrigerant of the circulation line having passed through the supercooling heat exchanger is lower than the target value.

The purpose of the present invention is to adjust a predetermined temperature of a vehicle-mounted device while suppressing power consumption. A vehicle air-conditioning system (1) is provided with: a heat pump unit (2) that circulates a refrigerant by repeating gas-liquid phase changes; an air-conditioning unit (3) that generates air-conditioned air, the temperature of which has been adjusted by heat exchange with a heat medium that exchanges heat with the refrigerant, and that blows the air-conditioned air out of the vehicle interior; and a device temperature adjustment means (5) for adjusting the temperature of a predetermined in-vehicle device (X) mounted on the vehicle. The heat pump unit (2) generates, for the refrigerant, at least a high-temperature refrigerant (Rh) of a first temperature, a low-temperature refrigerant (Rc) of a second temperature lower than the first temperature, and an intermediate-temperature refrigerant (Rm) of a third temperature between the first temperature and the second temperature, and the device temperature adjustment unit (5) adjusts the temperature of the in-vehicle device (X) using the intermediate-temperature refrigerant (Rm).

The invention relates to a method for operating a cooling device (10), a cooling device, and a test chamber with a cooling device, wherein, by means of the cooling device with a cooling circuit (11) comprising a refrigerant, a heat exchanger (12), an internal heat exchanger (19), a compressor (13), a condenser (14), and a controllable expansion element (15) of the cooling device, a temperature of at least -80 °C or lower is established at the heat exchanger, wherein the refrigerant undergoes a phase change in the heat exchanger, wherein the refrigerant is cooled on a high-pressure side (17) of the cooling circuit by means of the internal heat exchanger, wherein the cooling of the refrigerant on the high-pressure side by means of the internal heat exchanger is used to lower an evaporation temperature at the expansion element, and wherein a zeotropic refrigerant is used as the refrigerant.wherein the expansion element is controlled by a control device of the cooling unit in such a way that the refrigerant partially freezes during expansion at the expansion element.

The embodiment of the invention provides a heat recovery system based on a subcooler and an air conditioner and hot water all-in-one machine. The heat recovery system comprises a compression module, a first heat exchanger, the subcooler, a second heat exchanger and a water tank. The first heat exchanger, the subcooler and the second heat exchanger are sequentially connected in series. The compression module is connected to the first heat exchanger and the second heat exchanger. The water tank is connected to the subcooler, and the subcooler exchanges heat with the refrigerant condensed by the first heat exchanger or the second heat exchanger so as to transfer heat to the water tank. The first heat exchanger, the subcooler and the second heat exchanger are sequentially connected in series, so that the first heat exchanger serves as a condenser and the second heat exchanger serves as an evaporator in the refrigerating process, the second heat exchanger serves as a condenser and the first heat exchanger serves as an evaporator in the heating process, and separation of the condenser and the subcooler is achieved; the energy efficiency ratio of the system is improved; the subcooler is connected with the water tank, so that integration of an air conditioner and a hot water system is achieved, and the multiple requirements of users for refrigeration, heating and hot water supply are met.

A thermodynamic system 1 for cooling or heating at least a first container 11 containing food products of the liquid or semi-liquid type, comprising a circuit employing a heat exchanger fluid, preferably transcritical, having at least: - a compressor 2 provided with a first inlet "I1" and a first outlet "U1" for the heat exchanger fluid and with a second inlet "I2" and a second outlet "U2" for said heat exchanger fluid; - a first heat exchanger 4 comprising an inlet 4a for the heat exchanger fluid, connected to the second outlet "U2" of the compressor 2, and an outlet 4b for the heat exchanger fluid, the first heat exchanger 4 further comprising an inlet 4c for the service fluid and an outlet 4d for the service fluid; - a second heat exchanger 5 associated with at least a first container 11; - an inlet branch 35 for the heat exchanger fluid, extending from the outlet 4b for the heat exchanger fluid of the first heat exchanger 4 to an inlet 5a of the second heat exchanger 5; - an outlet branch 36 for the heat exchanger fluid, extending from the outlet 5b of the second heat exchanger 5 to the first inlet "I1" of the compressor 2; - a control and drive unit 8;

The application provides a refrigerating machine, a refrigerating unit and a flue gas cooling system, and the refrigerating machine comprises a compressor, a separation assembly, a condenser, an evaporator and an economizer, the separation assembly comprises a first oil separator and a second oil separator connected in series, the air inlet of the first oil separator is connected with the air outlet of the compressor, the oil return outlet of the second oil separator is connected with the air inlet of the compressor, the condenser is connected with the separation assembly and located downstream of the separation assembly, the evaporator is connected with the compressor, the economizer comprises a first chamber and a second chamber, the inlet of the first chamber is connected with the refrigerant outlet of the condenser, the outlet of the first chamber is connected with the refrigerant inlet of the evaporator, the inlet of the second chamber is connected with the outlet of the first chamber, and the outlet of the second chamber is connected with the refrigerant inlet of the compressor. The refrigerating machine provided by the application can not only effectively reduce the oil running phenomenon, improve the operation efficiency and reliability, but also ensure the stability and adaptability of the system under variable working conditions.

To provide a heat exchanger suitable for a simpler assembly process that can be semi-automated or fully automated. A heat exchanger for a cryogenic cooling device is provided having a first conduit, a second conduit, and a chamber, the chamber being positioned to receive a fluid from the first conduit, the second conduit being thermally coupled to an exterior of the chamber, the chamber having a first region and a second region, the first region being separated from the second region by a plate extending through the chamber, the plate including one or more openings that permit flow of the fluid from the first region to the second region.

Disclosed in the present application are a control method for a heat pump system, and a heat pump system. The heat pump system comprises a compressor, a condenser, an economizer and an evaporator, wherein the condenser comprises a first refrigerant channel and a water channel; and the economizer comprises a second refrigerant channel and a third refrigerant channel. The control method comprises: starting a compressor, and regulating, to a preset flow rate, both the flow rate of a refrigerant which enters a third refrigerant channel and the flow rate of a refrigerant which enters an evaporator; acquiring the water output temperature and a set temperature value of a water channel of a condenser; and on the basis of the water output temperature and the set temperature value, controlling the rotational speed of the compressor, such that the water output temperature approaches the set temperature value. The rotational speed of a compressor is controlled by using a water output temperature and a set temperature value, so that the heat pump system promptly responds to changes in the water output temperature, thereby improving the accuracy of regulating the water output temperature, thus achieving a quick response to the requirements of users for the water output temperature, and improving the user experience.

A refrigeration system, having a main loop operating with a first refrigerant and including a first heat exchanger unit connected between a compressor unit and an expansion unit upstream of an evaporation unit, includes a subcooling loop. The subcooling loop has a second refrigerant circulating therein via a pump unit and connects to the first heat exchanger unit to heat-up the second refrigerant. The subcooling loop runs to an air circulation unit located downstream the first heat exchanger unit to cool down the second refrigerant and warm-up air flowing into the air circulation unit.

The present invention is provided with: a plurality of heat exchange units, each of which is connected to a lower header on the underside and includes a refrigerant inlet / outlet tube whereby a refrigerant in an external refrigerant tube can flow in / out; and a connection tube which connects a heat exchange unit serving as a main heat exchange unit that exchanges heat between air and the refrigerant and that condenses the refrigerant and a heat exchange unit serving as a supercooling heat exchange unit that exchanges heat between air and the refrigerant passing through the main heat exchange unit and that supercools the refrigerant passing through the main heat exchange unit. The supercooling heat exchange unit includes a non-connection region where a heat transfer tube is not connected to one end on the top surface of the lower header. The refrigerant inlet / outlet tube is connected to the non-connection region. The refrigerant inlet / outlet tube on the refrigerant outflow side of the main heat exchange unit and the refrigerant inlet / outlet tube on the refrigerant inflow side of the supercooling heat exchange unit can be connected by the connection tube when condensation occurs on the main heat exchange unit.

Systems and methods for a regenerative ejector-based cooling cycle that utilizes an ejector as a driving force in the cooling loop to regenerate subcooling of the refrigerant in a single-stage cooling cycle.

Vehicle air conditioning unit with: a compressor (21) configured to compress and discharge a refrigerant; a radiator (15) configured to emit heat from the refrigerant; a heat exchanger (14) configured to absorb the heat in the refrigerant; an external heat exchanger (22) configured to release heat from the refrigerant or to absorb heat in the refrigerant; a first expansion valve (24) configured to expand the refrigerant flowing into the external heat exchanger (22); a second expansion valve (28) configured to expand the refrigerant flowing into the heat exchanger (14); a collector (30) configured to separate the refrigerant into a gas and a liquid and to allow the refrigerant to be drawn into the compressor (21), wherein the collector is provided in a refrigerant flow channel to a suction side of the compressor (21) into which the refrigerant is drawn; a heating refrigerant circuit (20a-20b-20c-20d-20e) configured to allow the refrigerant discharged by the compressor (21) to flow into the radiator (15) and release heat in the radiator (15), to allow the refrigerant flowing through the radiator (15) to flow into the outdoor heat exchanger (22) through the first expansion valve (24) and absorb the heat in the outdoor heat exchanger (22), and to allow the refrigerant flowing through the outdoor heat exchanger (22) to be drawn into the compressor (21) through the manifold; a heating and dehumidifying refrigerant circuit (20a-20b-20c-20e, 20a-20b-20f-20g-20h-20i-20e) configured to allow the refrigerant discharged by the compressor (21) to flow into the radiator (15) and release heat in the radiator (15), to allow a portion of the refrigerant that has flowed through the radiator (15) to flow into the outdoor heat exchanger (22) through the first expansion valve (24) and absorb heat in the outdoor heat exchanger (22), to allow the remaining refrigerant that has flowed through the radiator (15) to flow into the heat exchanger (14) through the second expansion valve (28) and absorb heat in the heat exchanger (14), and to allow the refrigerant that has flowed through the The air has flowed through the external heat exchanger (22) and the heat exchanger (14), and is drawn into the compressor (21) through the collector; a third expansion valve (25) configured to expand the refrigerant flowing from the radiator (15) into the heating refrigerant circuit and the heating and dehumidifying refrigerant circuit; a gas / liquid separator (29) configured to separate the refrigerant expanded through the third expansion valve (25) into a gaseous refrigerant and a liquid refrigerant; and a bypass circuit (20k) configured to allow at least some of the gaseous refrigerant separated in the gas / liquid separator to flow into a section of the compressor (21) through which the compressed refrigerant flows; and a fourth expansion valve (31) configured to expand the refrigerant flowing through the bypass circuit; and a valve opening control device configured to control the opening of the third expansion valve (25) such that the degree of subcooling of the refrigerant in the radiator (15) becomes a predetermined value, and to control the opening of the fourth expansion valve (31) such that the quantity of refrigerant flowing through the bypass circuit becomes a predetermined value.

Heat exchanger (1) for a thermal management system, in particular for a motor vehicle, comprising a plate stack (2) with at least two cooling circuit plates (4) and at least two refrigeration circuit plates (3), which are arranged in a stacking direction perpendicular to a plate surface of the cooling circuit plates (4) and refrigeration circuit plates (3) in the plate stack (2), wherein a refrigerant can be guided through a refrigerant path (5) formed on the refrigeration circuit plates (3) and a coolant can be guided through a coolant path (6) formed on the cooling circuit plates (4), wherein at least one collector device (11), in particular for outgassing gaseous refrigerant from the liquid refrigerant, is integrated into the plate stack (2).

A circulating process device (10), in particular a heat pump, which is designed to allow a refrigerant to circulate in it, comprising: a first evaporator (11) for converting the refrigerant into a gaseous state, which is arranged in a first evaporator section (V1), a second evaporator (12) which is arranged in a second evaporator section (V2) parallel to the first evaporator section (V1), and at least one pressure control unit (13) which is designed to set a lower pressure in the first evaporator section (V1) than in the second evaporator section (V2).

A brazed plate heat exchanger (100) including a plurality of first and second heat exchanger plates (110, 120), wherein the first heat exchanger plates (110) are formed with a first pattern of ridges (R1) and grooves (G1), and the second heat exchanger plates (120) are formed with a second pattern of ridges (R2a, R2b) and grooves (G2a, G2b) providing contact points between at least some crossing ridges and grooves of neighbouring plates under formation of interplate flow channels for fluids to exchange heat, said interplate flow channels being in selective fluid communication port openings (O1, O2, O3, O4). The first pattern of ridges and grooves is different from the second pattern of ridges and grooves, so that an interplate flow channel volume on one side of the first heat exchanger plates (110) is different from the interplate flow channel volume on the opposite side of the first heat exchanger plates (110). The heat exchanger (100) is provided with a retrofit port heat exchanger (400). A system and a method are also disclosed.

A vehicle thermal management device and a vehicle thermal management system therein may comprise: a radiator (227) configured to perform heat exchange between a coolant and air, a condenser (140) configured to perform heat exchange between a refrigerant and air, and a receiver-dryer (150) configured to remove moisture from the refrigerant discharged by the condenser (140), wherein the receiver-dryer (150) is configured to separate liquid refrigerant from gaseous refrigerant, and a heat exchange module (240) connected to the radiator (227) to allow the coolant to move between them, wherein the heat exchange module (240) is configured toselectively perform a heat exchange between the refrigerant in the receiver-dryer (150) and the coolant supplied by the radiator (227).

To enable an evaporator to adjust a refrigeration capacity while stably driving a compressor with suction injection using a bypass flow path.SOLUTION: A refrigeration device 10 comprises: a main circuit 15 in which a compressor 1, a condenser 2, an expansion valve 3 and an evaporator 4 are provided and which circulates a refrigerant; a bypass flow path 16 in which a flow control valve 11 is provided and which branches off from the main circuit 15, and in which the refrigerant liquefied in the condenser 2 is cooled by the flow control valve 11 and suctioned into the compressor 1 without passing through the evaporator 4; expansion control means 102 which controls the expansion valve 3 in accordance with a required degree of refrigeration; superheat degree control means 104 which controls the flow control valve 11 so that a superheat degree for a temperature equivalent to the suction pressure of the compressor 1 becomes a target value; and change means 105 which changes the target value of the superheat degree.SELECTED DRAWING: Figure 1