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.

An apparatus includes a flash tank that stores a refrigerant, a first load that uses the refrigerant to cool a first space, second and third loads, first and second compressors, and a high side heat exchanger configured to remove heat from the refrigerant. During a first mode of operation: the second load uses the refrigerant to cool a second space, the third load uses the refrigerant to cool a third space, the second compressor compresses the refrigerant from the second and third loads, and the first compressor compresses the refrigerant from the first load and the second compressor. During a second mode of operation, the second compressor compresses the refrigerant from the second load and directs the compressed refrigerant to the third load to defrost the third load.

A refrigeration system includes a dedicated defrost-mode compressor that delivers high pressure, high temperature refrigerant to one or more evaporators to defrost the evaporators.

A refrigeration system includes an expansion valve downstream of one or more medium temperature compressors. The expansion valve is configured to decrease pressure of a portion of refrigerant output by the one or more medium temperature compressors. When defrost operation of an evaporator is indicated, the refrigerant with decreased pressure from the expansion valve is provided to the evaporator for at least a period of time sufficient to defrost the evaporator.

Provided are a refrigerator and a cloud server that diagnose a cause of an abnormal state. According to an embodiment of the present disclosure, an abnormal state diagnosis unit included in the refrigerator or the cloud server generates information on the abnormal state of the refrigerator based on similarity between stored first group of information and a normal pattern, and a cause diagnosis unit generates, when the abnormal state diagnosis determines that a state of the refrigerator is an abnormal stte, information on cause of the abnormal state based on similarity between stored second group of information and a defect pattern.

A heat pump system includes a refrigerant circuit, at least one compressor, an evaporator, and a controller programmed to defrost the evaporator in a defrost mode, wherein in the defrost mode the controller is programmed to monitor the evaporator to detect frost creation thereon, and reduce the speed of the at least one compressor and/or reduce the number of some, but not all operating compressors of the at least one compressor, if frost creation is detected on the evaporator. In some embodiments, the controller is programmed to defrost the evaporator in a second defrost mode. In the second defrost mode the controller is programmed to monitor the evaporator to detect frost creation thereon, turn off the at least one compressor when frost is detected on the evaporator, and operate a fan to force ambient air over the evaporator to defrost the evaporator.

A dual redundant cooling system for a container is provided. The dual redundant cooling system includes a first cooling unit and a second cooling unit. The first cooling unit is positioned in a first cabinet attached to the container. The first cooling unit includes a first controller operating a first cooling loop to cool an interior of the container. The second cooling unit is positioned in a second cabinet attached to the container and adjacent the first cabinet. The second cooling unit includes a second controller operating a second cooling loop to cool the interior of the container. The first cooling unit and the first cooling loop are separate from the second cooling unit and the second cooling loop. The first controller and the second controller communicate a switch signal between each other so that either the first cooling unit is a primary cooling unit operating the first cooling loop or the second cooling unit is the primary cooling unit operating the second cooling loop. The switch signal switching the primary cooling unit.

A defrosting control method for a multi-split system is provided. A multi-split system comprises an outdoor unit and multiple indoor units. An expansion valve is provided on a connecting pipeline between each of the indoor units and the outdoor unit. When the expansion valve of each activated indoor unit is closed and the degree of opening of the expansion valve of each off-state indoor unit is less than or equal to a maximum set degree of opening, the system satisfies a defrosting requirement, and as a result the method controls the expansion valve of each activated indoor unit to remain closed, thereby resolving the issue of a dramatic temperature drop in a room having an activated indoor unit during defrosting and improving user satisfaction. The degree of opening of the expansion valve of a off-state indoor unit is Off_PLS, and is controlled such that Off_PLS=ALL_HP*Avg_PLS/Off_HP. The invention satisfies a defrosting requirement and reduces the degree of opening of the expansion valves as much as possible, thereby preventing damage to a compressor without affecting defrosting.

The present disclosure provides an air conditioner defrosting control method and device, and a storage medium and an air conditioner. The control method includes: setting a target discharge temperature of a compressor and an initial opening degree of a throttle device when an air conditioner performs defrosting according to an outdoor ambient temperature when the air conditioner meets a defrosting condition and enters a defrosting mode; controlling a defrosting operation of the air conditioner according to the target discharge temperature of the compressor and the initial opening degree of the throttle device; and controlling the air conditioner to exit the defrosting mode when a temperature of an outdoor heart exchanger of the air conditioner reaches a set temperature value.

A dual redundant cooling system for a container is provided. The dual redundant cooling system includes a first cooling unit and a second cooling unit. The first cooling unit is positioned in a first cabinet attached to the container. The first cooling unit includes a first controller operating a first cooling loop to cool an interior of the container. The second cooling unit is positioned in a second cabinet attached to the container and adjacent the first cabinet. The second cooling unit includes a second controller operating a second cooling loop to cool the interior of the container. The first cooling unit and the first cooling loop are separate from the second cooling unit and the second cooling loop. The first controller and the second controller communicate a switch signal between each other so that either the first cooling unit is a primary cooling unit operating the first cooling loop or the second cooling unit is the primary cooling unit operating the second cooling loop. The switch signal switching the primary cooling unit.