A heat pump device comprises a refrigerant circuit in which a compressor, a first indoor heat exchanger, an electric expansion valve, and a heat source-side heat exchanger are connected in a loop, a second indoor heat exchanger arranged between the compressor and the electric expansion valve and configured to store refrigerant during positive cycle defrost operation, an electromagnetic valve arranged between the second indoor heat exchanger and the electric expansion valve and configured to adjust an amount of refrigerant stored in the second indoor heat exchanger during the positive cycle defrost operation, and a control device that controls the compressor and the electric expansion valve.

A liquid slug reduction and charge compensator device for use in air conditioning and heat pump systems includes a housing having a cavity. The housing includes an inlet port providing an entry path into the cavity and an outlet port providing an exit path from the cavity. The housing further includes a liquid line port providing a refrigerant pathway into and out of the cavity. The liquid slug reduction and charge compensator device further comprises a flash tube extending through the cavity and providing a passageway through the cavity such that a hot gas refrigerant that enters the cavity through the inlet port causes a liquid refrigerant that enters the flash tube to evaporate.

Variable volume ratio compressors may be controlled using a switching parameter based on compressor speed and suction density to improve the matching of compressor volume ratio to desired discharge conditions. Delay periods may be implemented in the determination of when to change volume ratio to control the frequency of changes to the volume ratio. The switching parameter may be a product of the compressor speed and suction density. The volume ratio of the compressor may be controlled by switching valves directing pressure to a piston of a variable volume ratio system of the compressor.

A multimode system for cooling and desalination includes a humidification-dehumidification (HDH) system, an ejector cooling cycle (ECC) system and valves. The HDH system includes a heater, a humidifier and a dehumidifier. The ECC system includes a generator, an evaporator, an ejector and a condenser. The valves are configured to connect to inlets and outlets of the heater, the generator and a heat source so that by selectively opening and closing the valves, the heat source is connected to the heater while disconnected from the generator, or connected to the generator while disconnected from the heater, or connected to both the heater and the generator, or disconnected from both the heater and the generator. The ECC system and the HDH system are connected at the condenser for heat exchange.

A cooling system includes a coolant transmitter that transmits coolant at a pressure greater than atmospheric pressure. The cooling system also includes an evaporation vessel at atmospheric pressure. The evaporation vessel can contain an amount of coolant at the boiling point of the coolant. The cooling system also includes a pressure reducer fluidically coupled to the coolant transmitter and the evaporation vessel. The pressure reducer can include an orifice. The cooling system is configured such that heat is transferred from the coolant in the coolant transmitter to the coolant contained in the evaporation vessel. An exit stream conduit can fluidically couple the coolant transmitter and the pressure reducer, with the exit stream conduit diverting a portion of the coolant from the coolant transmitter to the evaporation vessel.

Thermal management systems include an open circuit refrigeration system featuring a first receiver configured to store a gas, a second receiver configured to store a liquid refrigerant fluid, an evaporator configured to extract heat from a heat load that contacts the evaporator, and an exhaust line, where the first receiver, the second receiver, the evaporator, and the exhaust line are connected to provide a refrigerant fluid flow path.

A transport refrigeration unit and a method for controlling the transport refrigeration unit, wherein the transport refrigeration unit has a controller device for operating a compressor of the transport refrigeration unit with a continuously-variable speed, which allows the compressor to run continuously but with a smooth gradient range of speed variations. The controller device allows the transport refrigeration unit to have a start-stop operation stage, continuous run operation stage, and/or a cycle-sentry operation stage.

A thermal management system is described. The thermal management system includes an open circuit refrigeration circuit that has a refrigerant fluid flow path, with the refrigerant fluid flow path including a receiver configured to store a refrigerant fluid, an ejector having a primary flow inlet configured to receive refrigerant, a liquid separator, an evaporator configured to extract heat from a heat load that contacts the evaporator, with the evaporator coupled to the ejector and the liquid separator, and an exhaust line coupled to a vapor side outlet of the liquid separator. In operation, the evaporator in the open circuit refrigeration circuit would be coupled to a heat load.

Thermal management systems include an open circuit refrigeration system featuring a first receiver configured to store a gas, a second receiver configured to store a liquid refrigerant fluid, an evaporator configured to extract heat from a heat load that contacts the evaporator, and an exhaust line, where the first receiver, the second receiver, the evaporator, and the exhaust line are connected to provide a refrigerant fluid flow path.

A heating, ventilation, and/or air conditioning (HVAC) unit includes a first sensor disposed adjacent to an inlet of an evaporator configured to receive an airflow. The HVAC unit includes a second sensor disposed adjacent to an outlet of a reheat coil positioned downstream of the evaporator and configured to expel the airflow. The HVAC unit also includes a controller configured to regulate operation of a modulating reheat valve to adjust flow of a working fluid in thermal communication with the airflow to control a difference between a measurement of the first sensor and a measurement of the second sensor.