The invention provides a highly reliable refrigeration apparatus configured to cool the interior of a casing of a heat source unit by means of a refrigerant and can reduce a possibility that liquid compression is caused by supply of the refrigerant to a heat exchanger for cooling the interior of the casing. An air conditioner (10) includes a heat source unit (100), a utilization unit (300) having a utilization heat exchanger (310) and constituting a refrigerant circuit (50) along with the heat source unit, and a controller. The heat source unit includes a compressor (110), a heat source-side heat exchanger (140) configured to cause heat exchange between a refrigerant and a heat source, a casing, a cooling heat exchanger (160) supplied with the refrigerant and configured to cool the interior of the casing, and a valve (162) configured to switch to supply or not to supply the cooling heat exchanger with the refrigerant. The controller configured to open or close the valve assesses, before the refrigerant is supplied to the cooling heat exchanger, whether or not the refrigerant flowing from the cooling heat exchanger toward the compressor comes into a wet state when the refrigerant is supplied, and determines whether or not to open the valve in accordance with an assessment result.

It is provided a refrigeration apparatus that uses liquid fluid as a heat source and is highly reliably configured to reduce the occurrence of dew condensation and freezing at a utilization unit during cooling operation in which a liquid fluid heat exchanger in a heat source unit functions as a radiator. An air conditioner (10) includes a heat source unit (100) having a compressor (110), a first heat exchanger (140) configured to cause heat exchange between a refrigerant and liquid fluid, a second heat exchanger (160) configured to cause heat exchange between the refrigerant and air, and a valve (162) configured to switch to supply or not to supply the second heat exchanger with the refrigerant, a utilization unit (300) constituting a refrigerant circuit (50) along with the heat source unit, and a controller (406) configured to control to operate the compressor and to open or close the valve (162). The controller opens the valve (162) to supply the second heat exchanger with the refrigerant to cause the second heat exchanger to function as a heat absorber when assessing that the refrigerant sent to the utilization unit needs to be decreased in quantity during cooling operation in which the first heat exchanger functions as a radiator.

A heat pump boiler is disclosed. The heat pump boiler includes a compressor. The heat pump boiler further includes an exterior heat exchanger that is configured to transfer heat between refrigerant and exterior air. The heat pump boiler further includes an interior heat exchanger that is configured to transfer heat between refrigerant and water. The heat pump boiler further includes a channel change valve that is configured to provide refrigerant compressed by the compressor to the exterior heat exchanger or the interior heat exchanger. The heat pump boiler further includes a first boiler heat exchanger that is configured to heat water that has passed through the interior heat exchanger from heat generated through combustion. The heat pump boiler further includes a second boiler heat exchanger that is configured to transfer heat between refrigerant and gas discharged from the first boiler heat exchanger.

A heat-pump using apparatus includes a refrigerant circuit and a heat medium circuit. The refrigerant circuit is capable of executing a heating operation and a cooling operation. A first expansion device is provided downstream of a reservoir, and a second expansion device is provided upstream of the reservoir, in the flow of refrigerant in the heating operation. A main circuit of the heat medium circuit includes a branching part and a joining part. An overpressure protection device is connected to a connection part which is located between a load-side heat exchanger and one of the branching part and the joining part or at the load-side heat exchanger. A refrigerant leakage detecting device is connected to the other of the branching part and the joining part, or between the other of the branching part and the joining part and the connection part, or to the connection part.

When refrigerant leakage occurs, a controller in an air conditioner performs first shutoff control to open a liquid relay shutoff valve and close an indoor expansion valve and a gas relay shutoff valve on the basis of information from a refrigerant leakage detector.

A chilling unit and a temperature control system using water circulation includes a refrigerant circuit, a pipe through which a heat medium flows, a flow switching device, a temperature sensor, a pressure sensor, and a controller. The refrigerant circuit includes a compressor, a pair of air-side heat exchangers, an expansion valve, and a heat-medium-side heat exchanger that are connected to each other by pipes, thereby enabling refrigerant to circulate in the refrigerant circuit. The flow switching device switches between refrigerant-circulation routes. The controller controls the compressor in accordance with a target outlet temperature, the temperature of the heat medium detected by the temperature sensor, and a pressure difference in the heat medium detected by the pressure sensor. When a load on a loading device decreases to a low level and the load is equal to or less than the lowest capacity of the compressor, the controller performs control to avoid starts and stops while keeping the compressor operating at the lowest capacity and controls the flow switching device so that one of the pair of air-side heat exchangers and the heat-medium-side heat exchanger are connected in parallel.

The invention concerns an air conditioning system for the conditioning of the air of a passenger compartment of a motor vehicle. The air conditioning system has a refrigerant circuit with a compressor, a refrigerant-coolant heat exchanger for desuperheating the refrigerant after the compression, a first refrigerant-air heat exchanger and a second refrigerant-air heat exchanger, and at least one coolant circuit. The coolant circuit has a heating heat exchanger for heating an air mass flow being supplied to the passenger compartment. The refrigerant-coolant heat exchanger is designed as a component of the coolant circuit having the heating heat exchanger. The air conditioning system is designed for an operation in refrigerator mode, in heat pump mode, and in afterheating mode for the heating, cooling, and dehumidification of the air being supplied to the passenger compartment. A valve arrangement switches the air conditioning system between the different operating modes.

An air conditioning system includes a bypass passage and a cooling-heating switching mechanism. The bypass passage is configured to be at least a part of a flow passage connecting a third port to a refrigerant inlet of a compressor. A linear expansion valve opens and closes the bypass passage. The cooling-heating switching mechanism includes check valves and four-way valves. The four-way valve causes a refrigerant outlet of the check valve to communicate with one of the refrigerant inlet and a refrigerant outlet of the compressor. The four-way valve causes a refrigerant inlet of the check valve to communicate with one of the refrigerant inlet and the refrigerant outlet of the compressor and causes a port to communicate with the other of the refrigerant inlet and the refrigerant outlet.

A cooling/heating switching unit includes first to third fittings, expansion valves and expansion-valve driving sections, a housing, a heat insulating material, and a refrigerant leak detection sensor. The first and second fittings respectively connect with a high/low-pressure-gas main pipe and a low-pressure-gas main pipe, which are linked to an outdoor unit. The third fitting connects with an indoor-unit connection pipe, which is linked to indoor units. The expansion valve for high/low-pressure-gas pipe, the expansion valve for low-pressure-gas pipe, and expansion-valve driving sections selectively connect the first or second fitting with the third fitting via a refrigerant pipe to control a flow direction of refrigerant. The housing houses the refrigerant pipe. The heat insulating material fills inside of the housing to insulate the refrigerant pipe arranged inside of the housing from heat. The refrigerant leak detection sensor is installed outside of the housing to detect leaked refrigerant.

When refrigerant leakage occurs, a controller in an air conditioner performs first shutoff control to open a liquid relay shutoff valve and close an indoor expansion valve and a gas relay shutoff valve on the basis of information from a refrigerant leakage detector.