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.

A multi-type air conditioner is provided including an outdoor unit and a plurality of indoor units connected to the outdoor unit by a liquid pipe and a gas pipe. The plurality of indoor units includes a first indoor unit including first and second heat exchangers and first and second heat exchanger connecting pipes, and a second indoor unit. An indoor heat exchanger connecting pipe connects the first and second indoor units, and a liquid pipe connecting tube connects the first indoor unit and the liquid pipe. Opening amounts of a first indoor expansion valve, and first and second bypass expansion valves provided in the first indoor unit are opened selectively to operate the first heat exchanger as a condenser and the second heat exchanger as an evaporator to continuously drive a dehumidification mode while maintaining a room temperature within a predefined range.

The invention relates to a flow circuit system (1) for a vehicle, with a first flow circuit (10) guiding a first fluid and operable as a heat pump, and a second flow circuit (50) with a conveying device (31) guiding a second fluid, and a switching device (35), wherein in the provided flow direction of the first fluid downstream of a compressor (3) and upstream of an expansion element (15), at least one first heat exchanger (7) between the first and second fluids, wherein the second flow circuit (50) has at least two flow circuit modes, wherein in the first flow circuit mode, apart from the at least one conveying device (31) for the second fluid and the at least one first heat exchanger (7), at least one outside heat exchanger (37) which may be flowed through by the second fluid and is configured as a radiator is connected to the second flow circuit (50), and in the second flow circuit mode this at least one outside heat exchanger (37) is not connected to the at least second flow circuit (50) containing the conveyor device (31) and the first heat exchanger (7), and preferably is also a heating flow circuit. In this way more flexibility is created in the flow circuit system (1) for a vehicle.

Disclosed is an air conditioning system having: a first HVAC assembly comprising an indoor heat exchanger and a fan; a first sensor, configured to sense a first temperature reading, operably coupled to the indoor heat exchanger; a second sensor, configured to sense a second temperature reading, positioned downstream of the first sensor and detached from the indoor heat exchanger; and a system controller configured to activate the fan to deliver airflow across the indoor heat exchanger when the difference between the first temperature reading and the second temperature reading is greater than or equal to a predetermined threshold, the temperate differing being checked when the first HVAC assembly is in an inactive mode and the fan and a compressor operably connected to the first HVAC assembly are in an inactive mode.

An economizer module for increasing energy efficiency of a pumped refrigerant cooling system is connected to a refrigerant pumping unit including a primary pump connected with heat extractor(s) via a primary circuit and a primary heat exchanger connected with a condensing unit via a secondary circuit. The economizer module includes a control panel with control software, a secondary heat exchanger connected with the heat extractor(s) via the primary circuit and with the primary heat exchanger, a cooler connected with the secondary heat exchanger via an economizer circuit, and a secondary pump connected between the cooler and the secondary heat exchanger. The control panel executes the control software to control fluid flow in the economizer circuit via the secondary pump so as to use ambient air to reject heat from working fluid being used to collect heat from refrigerant in said primary circuit before said heat travels to said secondary circuit.

An air conditioner and a control method thereof. The air conditioner includes an indoor unit including an indoor heat exchanger and an indoor fan, an outdoor unit connected to the indoor unit and including an outdoor heat exchanger, an outdoor fan, a compressor, an expansion valve, and a four-way valve, and at least one processor configured to perform a test operation by controlling the indoor unit and the outdoor unit. Based on an outdoor temperature being less than a predetermined reference temperature, the at least one processor is configured to determine whether the indoor unit and the outdoor unit operate normally, by continuously performing a heating operation and a defrosting operation during the test operation.

A refrigeration system includes a main refrigeration circuit for holding refrigerant fluid, the main refrigeration circuit including: a compression device 12, a heat rejecting heat exchanger 14, an expansion device 18 and a heat absorbing heat exchanger 16. In addition, the refrigeration system includes a buffer tank 20 attached to the main refrigeration circuit, with valves 22, 24 for controlling flow of refrigerant fluid between the main refrigeration circuit and the buffer tank 20. The refrigeration system is arranged such that the valves 22, 24 are controlled to transfer refrigerant fluid between the main refrigeration circuit and the buffer tank 20 based on a measure of sub-cooling in the main refrigeration circuit.

An air conditioner includes an outdoor unit in which a refrigerant circulates; an indoor unit in which water circulates; a heat exchange device including a heat exchanger that connects the outdoor unit to the indoor unit and performs heat exchange between the refrigerant and the water; a first outdoor unit connection pipe configured to connect the outdoor unit and the heat exchange device, a high-pressure gaseous refrigerant flowing in the first outdoor unit connection pipe; a second outdoor unit connection pipe configured to connect the outdoor unit and the heat exchange device, a low-pressure gaseous refrigerant flowing in the second outdoor unit connection pipe; a third outdoor unit connection pipe configured to connect the outdoor unit and the heat exchange device, a liquid refrigerant lowing in the third outdoor unit connection pipe; a bypass pipe configured to communicate the third outdoor unit connection pipe and the second outdoor unit connection pipe; and a bypass valve provided in the bypass pipe.

A sensor control system includes: a refrigerant leak sensor configured to, when powered, measure an amount of a refrigerant present in air outside of a heat exchanger of a refrigeration system, where the heat exchanger is located within a building that is at least one of heated and cooled by the refrigeration system; and a power control module configured to one of: continuously power the refrigerant leak sensor; and disconnect the refrigerant leak sensor from power when a blower that moves air past the heat exchanger is on.

Devices, systems, and methods are disclosed for cooling using both air and/or liquid cooling sub circuits. A vapor compression cooling system having both an air and liquid cooling sub circuit designed to service high sensible process heat loads that cannot be solely cooled by either liquid or air is provided.