Systems and methods for controlled subcooling of working fluid in a heating, ventilation, air conditioning and refrigeration (HVACR) system through a suction line heat exchanger are disclosed. The suction line heat exchanger may receive a first fluid flow travelling to a suction of the compressor in the HVACR system and second flow of working fluid that is travelling from a heat exchanger receiving the discharge of the compressor to an expansion device. Superheating of the first working fluid may be determined based on temperature measurements prior to and following the suction line heat exchanger. The superheating may be used to control the quantity of the second flow of working fluid introduced into the suction line heat exchanger, for example to maintain superheat that is below a threshold value. These systems may include chillers and heat pump systems, and methods may be applied to chillers or heat pump systems.

The present invention provides a system and method for an improved multistage, cascade refrigeration system using hot gas defrost to rid the evaporator of ice build-up which accumulates over time, while the air in the evaporator enclosure remains below the freezing point of water. The present invention thus provides greater defrost flexibility with increased ease of design and implementation than current refrigeration systems, which allows for more robust hot gas defrost function for multistage refrigeration systems, such that it is unaffected by temperature changes of the condensing fluid (ambient air temperature for air cooled condensers, water temperature for water cooled condensers), and can be readily adapted to any refrigerant suitable for a selected temperature range.

Disclosed is a CO2 based refrigeration system comprising a condenser for transferring heat from a CO2 refrigerant of the refrigeration system to an air stream. The system further comprises an indirect evaporative cooler arranged to cool an air stream and supply the cooled air to the condenser to facilitate the transfer of heat from the CO2 refrigerant.

A temperature control system includes a first pump, a second pump, a temperature adjusting unit, a first flow passage, a second flow passage, a first valve disposed in the first flow passage, a second valve disposed in the second flow passage, a first bypass flow passage connecting the first flow passage to the second flow passage on the temperature adjusting unit side of the first and second valves, a second bypass flow passage connecting the first flow passage to the second flow passage on the flow passage side of the first and second valves, a third valve disposed in the first bypass flow passage, and a fourth valve disposed in the second bypass flow passage. At least one of a pair of the first valve and the second valve, and a pair of the third valve and the fourth valve is a pair of flow rate adjustable valves.

An air conditioner and a control method for an air conditioner are provided. The air conditioner may include a compressor, a flow switch installed at an outlet side of the compressor, a first guide pipe extending from the flow switch to an outdoor heat exchanger, a second guide pipe extending from the flow switch to an indoor unit, a third guide pipe extending from the outdoor heat exchanger to the indoor unit, a bypass passage extending from the second guide pipe to the third guide pipe to allow at least a portion of the refrigerant in the second guide pipe to be bypassed to the third guide pipe or to allow at least a portion of the refrigerant in the third guide pipe to be bypassed to the second guide pipe, and a bypass valve installed on the bypass passage.

A thermodynamic system for cooling or heating at least a first container containing food products of the liquid or semi-liquid type, including a circuit employing a heat exchanger fluid, having at least: a compressor having at least one inlet for the heat exchanger fluid and one outlet for the heat exchanger fluid; a first heat exchanger connected to the outlet of the compressor; at least one first expansion element connected to an outlet of the first heat exchanger; a second heat exchanger which can be associated with the first container and which has an inlet connected to an outlet of the at least one first expansion element; a return duct having an inlet portion connected to an outlet of the second heat exchanger and an outlet portion connected to the inlet of the compressor.

A cooling device comprising a cooling circuit, is described. The cooling circuit further comprises a compressor adapted to compress cooling agent present in the cooling circuit during an active cooling mode, wherein the compressed cooling agent contains lubricant oil from the compressor; a condensing unit connected to the compressor by a first fluid line of the cooling circuit; and an evaporating unit, which is connected to the condensing unit by a second fluid line of the cooling circuit. The cooling circuit further comprises an expansion device arranged in the second fluid line; and an additional evaporator connected to the evaporating unit by a third fluid line of the cooling circuit, and connected to the compressor by a fourth fluid line of the cooling circuit.

A refrigeration apparatus includes: a refrigerant circuit through which refrigerant circulates; a controller to execute a plurality of refrigerant shortage sensing functions of sensing a shortage of an amount of the refrigerant; and an input device through which an operation mode to be set is input into the controller. The operation mode includes: a first mode in which energy-saving performance is emphasized; and a second mode in which the refrigeration apparatus is permitted to operate in a range in which reliability is ensured. In accordance with the operation mode set through the input device, the controller determines which one of sensing results obtained by the refrigerant shortage sensing functions is enabled and which one of sensing results obtained by the refrigerant shortage sensing functions is disabled. When a sensing result determined to be enabled shows a refrigerant shortage, the controller gives a notification about the refrigerant shortage.

A thermodynamic system for cooling or heating at least a first container containing food products of the liquid or semi-liquid type, including a circuit employing a heat exchanger fluid, having at least: a compressor having at least one inlet for the heat exchanger fluid and one outlet for the heat exchanger fluid; a first heat exchanger connected to the outlet of the compressor; at least one first expansion element connected to an outlet of the first heat exchanger; a second heat exchanger which can be associated with the first container and which has an inlet connected to an outlet of the at least one first expansion element; a return duct having an inlet portion connected to an outlet of the second heat exchanger and an outlet portion connected to the inlet of the compressor.

A refrigeration cycle apparatus includes a refrigerant circuit including a compressor, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger connected to each other via refrigerant pipes. The outdoor heat exchanger includes a heat transfer pipe, and a plurality of fins. The outdoor heat exchanger is configured so that a ratio of a heat capacity of the plurality of fins to a total of heat capacities of the heat transfer pipe and the plurality of fins is not more than 50%. The refrigeration cycle apparatus has a mixed defrosting operation mode in which a hot gas defrosting operation and a reverse-defrosting operation are performed in sequence. In the hot gas defrosting operation, hot gas discharged from the compressor is supplied to the outdoor heat exchanger. In the reverse-defrosting operation, refrigerant passing through the indoor heat exchanger is supplied from the compressor to the outdoor heat exchanger.