An air conditioner switches between a normal refrigeration cycle and a defrosting refrigeration cycle, and includes: a refrigerant circuit that connects a first heat exchanger, a second heat exchanger, a radiation panel, and an expansion valve that regulates a flow rate of a refrigerant flowing through the radiation panel; and a controller that causes the air conditioner to switch between the normal refrigeration cycle and the defrosting cycle. During the normal refrigeration cycle, the radiation panel performs cooling or heating. During the defrosting cycle, the first heat exchanger serves as a radiator and the second heat exchanger serves as an evaporator. During the defrosting cycle, the controller causes the expansion valve to be in a fully closed state.

A refrigeration cycle apparatus includes: a compressor, a first outdoor heat exchanger, and a second outdoor heat exchanger that; and a flow path switching mechanism configured to switch a flow direction of refrigerant compressed by the compressor in the refrigerant circuit. The first outdoor heat exchanger and the second outdoor heat exchanger are arranged to allow the refrigerant to flow in parallel in the refrigerant circuit. The refrigeration cycle apparatus further includes a flow rate adjustment mechanism configured to adjust an amount of refrigerant flowing through the second outdoor heat exchanger. When switching between a cooling operation and a heating operation, the flow path switching mechanism switches the flow direction of the refrigerant while the flow rate adjustment mechanism temporarily closes a refrigerant flow path to the second outdoor heat exchanger.

An air conditioner comprises: a refrigerant circuit configured to circulate refrigerant through a compressor, a condenser, an LEV and an evaporator; a first temperature sensor configured to sense the temperature of liquid refrigerant at the inlet port of the evaporator; and a controller configured to control the compressor and the LEV. In a case where a temperature sensed by the first temperature sensor is lower than a frosting reference temperature, the controller increases the opening degree of the LEV and also increases the operating frequency of the compressor as compared with a case where the temperature sensed by the first temperature sensor is higher than the frosting reference temperature.

A system for controlling or optimizing the performance of a vapor compression system by modifying the actuator commands via an output interface, that realizes thermofluid property functions and their derivatives as spline functions which are represented in a coordinate system that is aligned with a fluid saturation curve. The system includes an interface configured to receive measurement data from sensors, a memory configured to store thermofluid property data and computer-executable programs including a B-spline method, and a processor for performing the computer-implemented method. The processor is configured to take as input two thermofluid property variables, and compute a coordinate transformation in which one axis of the coordinates is aligned with the liquid and vapor saturation curves. In the saturation-curve aligned coordinates, a spline function represents the thermofluid property function, with coefficients and knots stored in memory. The spline function is constructed in a manner such that derivatives of the thermofluid property function may be discontinuous across the saturation curve.

A metering device may automatically control fluid flow through a valve. A control system may alter the automatic control of a metering device. In some implementations, a predetermined event may occur to alter the automatic control of the metering device.

A refrigeration cycle apparatus includes a first refrigerant circuit including a first compressor, a first heat exchanger, a first refrigerant flow path of a second heat exchanger, a first expansion device, a third heat exchanger, and a second refrigerant flow path of a fourth heat exchanger, and a second refrigerant circuit including a second compressor, a fifth heat exchanger, a second expansion device, a third refrigerant flow path of the second heat exchanger, and a fourth refrigerant flow path of the fourth heat exchanger, a first refrigerant flows through, in order, the first compressor, the first heat exchanger, the first refrigerant flow path, the first expansion device, the third heat exchanger, and the second refrigerant flow path, the second refrigerant flows through, in order, the second compressor, the fifth heat exchanger, the second expansion device, the third refrigerant flow path, and the fourth refrigerant flow path.

A method of detecting electrical failure in a refrigeration system is provided. The method includes determining whether a present superheat of the refrigeration system is between a maximum superheat and a minimum superheat for the refrigeration system, the maximum superheat and the minimum superheat defining a normal operating range. The method also includes detecting an electrical property of an expansion valve assembly of the refrigeration system responsive to the superheat being outside the normal operating range. The method further includes determining whether the expansion valve assembly as experienced an electrical failure based on at least the electrical property. A signal indicating that the expansion valve has experienced an electrical failure is generated based on a determination that the expansion valve assembly has experienced the electrical failure.

A vehicle air-conditioning apparatus is provided which is capable of expanding an effective range of a dehumidifying and heating mode to achieve comfortable vehicle interior air conditioning. A control device (controller) executes a dehumidifying and heating mode to let a refrigerant discharged from a compressor 2 radiate heat in a radiator 4, let a part of the refrigerant flow from a bypass circuit (refrigerant pipe 13F) to an indoor expansion valve 8, and let the residual refrigerant flow through an outdoor expansion valve 6. In the dehumidifying and heating mode, the control device has a state of controlling the operation of the compressor 2, based on a heat absorber temperature Te and executes a radiator temperature priority mode which enlarges a capability of the compressor when heat radiation in the radiator is insufficient.

A free cooling outdoor unit includes: a refrigerant circuit through which refrigerant circulates; a brine circuit through which brine circulates; a water circuit through which water circulates; a fan configured to send air to the second heat exchanger; a flow control valve configured to control a circulation amount of the brine in the brine circuit; a water temperature detection sensor configured to detect a water temperature in the water circuit; an outside air temperature sensor; and a controller configured to control, where the outside air temperature is equal to or lower than a freezing temperature of the brine, the circulation amount of the brine based on the water temperature such that a brine temperature is prevented from reaching a temperature equal to or lower than the freezing temperature of the brine.

A heat pump system provides at least six modes of heating, cooling, and/or domestic water heating operation, where domestic water heating may occur concurrently with heating or cooling a space in a structure. The heat pump system comprises a desuperheater positioned downstream of the compressor and operable as a desuperheater, a condenser or an evaporator, a source heat exchanger operable as either a condenser or an evaporator, a load heat exchanger operable as either a condenser or an evaporator, a reversing valve positioned downstream of the desuperheater heat exchanger and configured to alternately direct refrigerant flow from the desuperheater heat exchanger to one of the load heat exchanger and the source heat exchanger and to alternately return refrigerant flow from the other of the load heat exchanger and the source heat exchanger to the compressor, and an expansion valve positioned between the load heat exchanger and the source heat exchanger.