Disclosed is a refrigeration system, comprising refrigeration system components, a connecting pipeline, a switch structure, and discharging channels (123, 124; 623, 624). The refrigeration system components comprise three heat exchangers (101; 102; 112). The refrigeration system components can be connected via the connecting pipeline, and are combined into different working systems via the switch structure. When two heat exchangers are selected by the switch structure to form one working system and the saturation temperature corresponding to the internal pressure of the unselected heat exchanger is higher than the medium or environment temperature of the heat exchanger, a liquid refrigerant accumulates inside the non-working heat exchanger. According to the refrigeration system, the switch structure is arranged at either end of the non-working heat exchanger, so that the non-working heat exchanger is isolated from a working system cycle, and under the condition where the pressure at a low-pressure side (C; Q) of the working system is less than the internal pressure of the non-working heat exchanger, additional discharging channels (123, 124; 623, 624) communicate with the non-working heat exchanger and the low-pressure side (C; Q) of the working system, so that the refrigerant accumulating in the non-working heat exchanger is transferred to the system cycle, avoiding a lack of refrigerant in the system cycle.

A refrigeration cycle apparatus includes a hot water tank, a heat source for heating water in the hot water tank, and a refrigeration cycle circuit that includes an indoor heat exchanger, a heat-source heat exchanger, and a water heat exchanger. The indoor heat exchanger may operate as a condenser. When an outside temperature is greater than a specified temperature, the refrigeration cycle apparatus operates in a first state in which the heat-source heat exchanger operates as an evaporator and the water heat exchanger does not operate. When the outside temperature is less than the specified temperature, the refrigeration cycle apparatus operates in a second state in which the water heat exchanger operates as an evaporator and refrigerant therein absorbs heat from water in the hot water tank heated by the heat source and the heat-source heat exchanger does not operate.

Provided is an indoor unit for a refrigeration apparatus that is capable of detecting a refrigerant leak while suppressing condensation on a refrigerant gas sensor. An indoor unit (50) for an air conditioner (100) including a refrigerant circuit (10) includes a casing (60), an indoor fan (53), and a refrigerant gas sensor (81). The refrigerant circuit (10) has refrigerant charged therein, and performs a refrigeration cycle. The casing (60) houses at least a portion of the refrigerant circuit (10), and has a blow-out port (64) that opens in a direction other than an up-down direction. The indoor fan (53) is housed in the casing (60), and generates an air flow (F) directed from the blow-out port (64) to outside the casing (60). The refrigerant gas sensor (81) is capable of detecting a refrigerant gas below a bottom surface (63) of the casing (60).

A data center cooling system has an indoor portion wherein heat is absorbed from components in the data center, and an outdoor heat exchanger portion wherein outside air is used to cool a first heat transfer fluid (e.g., water) present in at least the outdoor heat exchanger portion of the cooling system during a first mode. When an appropriate time has been reached to switch from the first mode to a second mode, the outdoor heat exchanger portion of the data cooling system is switched to a second heat transfer fluid, which is a relatively low performance heat transfer fluid (compared to the first fluid). It has a second heat transfer fluid freezing point, lower than the first heat transfer fluid freezing point, and sufficiently low to operate without freezing when the outdoor air temperature drops below a first predetermined relationship with the first heat transfer fluid freezing point.

A method of conditioning air includes controlling a secondary refrigerant flow control valve to select between a first mode in which refrigerant flows from a discharge line to a main refrigerant flow control valve, and a second mode in which refrigerant flows from the discharge line to a gas reheat heat exchanger and then flows to the main refrigerant flow control valve. A heat transfer medium flow control valve is controlled to adjust the flow of the heat transfer medium into a heat source side heat exchanger. The heat transfer medium flow control valve allows the heat transfer medium to flow to the heat source side heat exchanger when the secondary refrigerant flow control valve is in the first mode, and adjusts the flow of the heat transfer medium to the heat source side heat exchanger when the secondary refrigerant flow control valve is in the second mode.

An air conditioner is disclosed. The air conditioner comprises: an indoor unit having an indoor heat exchanger installed therein; a first outdoor unit having a first outdoor heat exchanger and a first compressor installed therein; a second outdoor unit having a second outdoor heat exchanger and a second compressor installed therein; an auxiliary module which connects the indoor unit, the first outdoor unit, and the second outdoor unit; a first connection line by which the auxiliary module is connected to the first outdoor unit; a second connection line by which the auxiliary module is connected to the second outdoor unit; and a two-stage compression line by which the first outdoor unit is connected to the second outdoor unit.

Modular heating and cooling systems may include one or more modules connected to a fluid input and fluid output. Conventional modular heating and cooling systems typically use a single fluid in the cooling, heating and source fluid loops due to the mixing of fluids in the system. According to an aspect there is provided a modular heating system comprising at least one heating and cooling apparatus. The apparatus comprises a first heat exchanger, a second heat exchanger and a third heat exchanger. The apparatus further comprises a refrigerant line system coupled to the first (e.g. cooling), second (e.g. heating) and third (e.g. source) heat exchangers and configurable for selectively directing refrigerant fluid through the heat exchanger to provide multiple modes of operation. The heating, cooling and source fluid loops may be separate and independent such that the fluids do not mix.

Proposed a gas heat-pump system including: a compressor compressing refrigerant and discharging the compressed refrigerant; an engine providing a drive force to the compressor; a radiator that cools coolant which is heated while passing through the engine; an indoor heat exchanger causing heat exchange to occur between indoor air and the refrigerant and thus cooling or heating an indoor space; an outdoor heat exchanger condensing the refrigerant; a four-way valve switching a flow direction of the refrigerant in such a manner that the refrigerant discharged from the compressor flows to the outdoor heat exchanger in a cooling operation mode and flows to the indoor heat exchanger in a heating operation mode; and a hot-water storage tank causing the heat exchange to occur between stored water and the refrigerant, and thus cooling the refrigerant in the cooling operation mode and heating the refrigerant in the heating operation mode.

A data center cooling system has an indoor portion wherein heat is absorbed from components in the data center, and an outdoor heat exchanger portion wherein outside air is used to cool a first heat transfer fluid (e.g., water) present in at least the outdoor heat exchanger portion of the cooling system during a first mode. When an appropriate time has been reached to switch from the first mode to a second mode, the outdoor heat exchanger portion of the data cooling system is switched to a second heat transfer fluid, which is a relatively low performance heat transfer fluid (compared to the first fluid). It has a second heat transfer fluid freezing point, lower than the first heat transfer fluid freezing point, and sufficiently low to operate without freezing when the outdoor air temperature drops below a first predetermined relationship with the first heat transfer fluid freezing point.

The refrigeration cycle apparatus includes a refrigerant circuit, a controller to control the refrigerant circuit, a bypass flow path, and a flow control valve. The bypass flow path communicates between the discharge side of the compressor and the first outdoor heat exchanger or between the discharge side of the compressor and the second outdoor heat exchanger. The flow control valve is provided to the bypass flow path. The refrigerant circuit is configured to be able to perform a heating defrosting simultaneous operation. The heating defrosting simultaneous operation is an operation of supplying part of the refrigerant discharged from the compressor to one of the first outdoor heat exchanger and the second outdoor heat exchanger via the bypass flow path, causing the other of the first outdoor heat exchanger and the second outdoor heat exchanger to serve as an evaporator, and causing the indoor heat exchanger to serve as a condenser.