A heat pump system includes a compression device 12, a heat rejecting heat exchanger 14, an expansion device 18 and a heat absorbing heat exchanger 16; wherein the expansion device 18 provides a controllable degree of expansion. The heat pump system is operated in accordance with a method including determining a temperature indicative of frosting conditions on an exterior surface of the heat absorbing heat exchanger 16; operating the heat pump system in a first mode if the temperature indicative of frosting conditions is above a threshold value, and operating the heat pump system in a second mode if the temperature indicative of frosting conditions is within a range of temperatures that is below the threshold value.

The application relates to a cooling system, the cooling system having: an evaporator, a first compressor, a second compressor, a cooling component, an expansion device and a line system that connects the evaporator, the first compressor, the second compressor, the cooling component and the expansion device to one another. The cooling system includes a refrigerant, wherein the refrigerant comprises carbon dioxide. The first compressor and the second compressor are arranged in series with one another. The application also relates to a corresponding laboratory instrument.

Multi-compressor chiller systems can be efficiently operated by determining real time efficiency curves for the compressors currently in operation, along with any compressors that may be added to address demand, and using these efficiency curves to determine changes to compressor operation to improve efficiency in meeting chiller demand. The efficiency curves can be parabolic curves. The data used to determine the efficiency curves can be obtained through operation at a variety of lift points and a variety of load points within those lift points. The efficiency curves can be solved to find intersections where there may be staging points for adding or subtracting compressors from operation to efficiently meet demand. This operation can be automated through a controller of a control system for the multi-compressor chiller system.

A reversible heat pump system with one bi-flow expansion device. A four-way valve in the refrigerant circuit may be configured in either a cooling mode or a heating mode. In the cooling mode, a compressor is operable to flow a refrigerant out a compressor outlet and through the bi-flow expansion device in a first direction. In the heating mode, the compressor is operable to flow the refrigerant out the compressor outlet and through the bi-flow expansion device in a second direction, opposite the first direction. Thus, only one thermal expansion device is needed for a reversible heat pump heating, ventilation, and air conditioning (HVAC) system without the need for bypass lines and check valves around the bi-flow expansion device. Further, if an accumulator is included before the compressor, the bi-flow expansion device may be controlled to store at least some refrigerant in the accumulator, thus allowing the evaporator superheat to be lower than if the accumulator were not used.

A refrigeration cycle apparatus is a refrigeration cycle apparatus having a refrigerant circuit having a compressor, a condenser, a supercooler, an expansion device, and an evaporator connected by a refrigerant pipe, and configured to circulate refrigerant containing refrigerant having a temperature gradient, wherein the supercooler sets a degree of supercooling of the refrigerant, which is a temperature difference between a temperature from the condenser to a refrigerant flow inlet of the supercooler and a temperature in a refrigerant flow outlet on a downstream side of the supercooler, to be larger than the temperature gradient generated at a time of refrigerant shortage of the refrigerant between the refrigerant flow inlet and the refrigerant flow outlet of the supercooler, the refrigeration cycle apparatus including a refrigerant amount determination unit configured to compare a determination threshold value set to a value larger than the temperature gradient of the refrigerant with the degree of supercooling of the refrigerant, and determine whether or not there is a shortage of a refrigerant amount filled in the refrigerant circuit.

A refrigeration cycle device includes a third refrigerant passage connecting a utilization heat exchanger to a first expansion valve, a fourth refrigerant passage connecting the first expansion valve to a receiver, a fifth refrigerant passage connecting the receiver to a second expansion valve, a sixth refrigerant passage connecting the second expansion valve to an air heat exchanger, a hot-gas bypass passage connecting a discharge passage to the sixth refrigerant passage, a hot-gas bypass valve, an internal heat exchanger to exchange heat between the liquid refrigerant inside the receiver and the refrigerant passing through the suction passage, a liquid bypass passage including an inlet portion connected to the fourth refrigerant passage, the fifth refrigerant passage, or a lower portion of the receiver, and an outlet portion connected to the suction passage upstream of the internal heat exchanger, and a liquid bypass valve.

The propagation of a disproportionation reaction of a refrigerant is suppressed. Disclosed is a method that uses a composition as a refrigerant in a refrigerant circuit, in which the composition includes one or more compounds selected from the group consisting of ethylene-based fluoroolefins, 2,3,3,3-tetrafluoropropene, and 1,3,3,3-tetrafluoropropene, and the refrigerant circuit includes a compressor, a four-way switching valve, and a first refrigerant pipe connecting the compressor and the four-way switching valve, the first refrigerant pipe having a pipe diameter less than or equal to ⅜ inch or a length greater than or equal to 5 cm.

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.

The heat source controller transmits the drive permission signal (SE) to the utilization controller when the compression element is drivable. The utilization controller opens a utilization expansion valve when heat exchange in a utilization heat exchanger is required, on condition that the utilization controller receive the drive permission signal (SE).

An ice maker for forming ice during a cooling cycle, the ice maker having a variable-speed compressor, a condenser, and an evaporator, wherein the variable-speed compressor, the condenser, and the evaporator are in fluid communication by one or more refrigerant lines. The ice maker further includes a freeze plate thermally coupled to the evaporator, a water pump, a sensing device for identifying a state of the cooling cycle, and a controller adapted to control the speed of the variable-speed compressor based on the identified state of the cooling cycle. The ice maker may also include a variable-speed condenser fan which may be controlled by the controller based on the identified state of the cooling cycle. Additionally, the water pump may be a variable-speed water pump which may be controlled by the controller based on the identified state of the cooling cycle.