Heat pump system (100) comprising at least one heat medium circuit (210,220,230,240,250,310,320,410,420,430,440,450,460) in turn comprising a compressor (211), an expansion valve (232,242), at least two different primary heat sources or sinks selected from outdoor air, a water body, the ground or exhaust air, at least one of two different secondary heat sources or sinks selected from indoors air, pool water and tap water, a respective temperature sensor (412,432) at each of said primary heat sources or sinks, a valve means (421,431,451) for selectively directing the primary-side heat medium to at least one of said primary heat exchanging means, and a control means (500). The invention is characterised in that, in a secondary-side heating operating mode, the temperature of said primary heat sources or sinks is measured, and in that the primary-side heat medium is directed only to available primary heat exchanging means associated with the heat sources or sinks with the highest temperature. The invention also relates to a method.

There is provided a vehicle air conditioning apparatus capable of removing frost formed on an outdoor heat exchanger at the same time as cooling of a battery. The vehicle air conditioning apparatus performs the operation in a first battery cooling mode, a second battery cooling mode, or a solo battery cooling mode, when it is determined that the battery needs to be cooled and also determined that the frost formed on the outdoor heat exchanger needs to be removed. By this means, it is possible to cool the battery and melt the frost formed on the outdoor heat exchanger at the same time by the battery cooling operation, and therefore it is possible to reduce the power consumption compared to the case where the battery cooling operation and the defrosting operation are performed individually.

This air conditioning device for a vehicle comprises: an indoor condenser; an indoor evaporator; a first expansion valve; a second expansion valve; a refrigerant line; an expansion valve control detector; and a controller. The expansion valve control detector is constituted by: only one temperature sensor that detects the temperature of refrigerant in an inter-expansion valve line of the refrigerant line; and only one pressure sensor that detects the pressure of the refrigerant in the inter-expansion valve line. During a cooling operation, the controller issues, to the first expansion valve, an opening command corresponding to a state quantity of the refrigerant that has been detected by the expansion valve control detector, and during a heating operation, the controller issues, to the second expansion valve, an opening command corresponding to a state quantity of the refrigerant that has been detected by the expansion valve control detector.

A method controls the level of liquid within an evaporator of a flooded-type chiller without level sensors. The flooded-type chiller includes at least one compressor, a condenser, an expansion valve and an evaporator. A number of sensors positioned in the system measures a number of first parameter information values. A controller calculates a number of second parameter information values based on the measured first parameter information values and further determines a virtual refrigerant level as a control signal based on the second parameter information values. Based on the determined virtual refrigerant level, the controller opens, closes or holds the expansion valve with respect to a dead zone for maintaining a pre-defined target refrigerant level so as to provide the desired refrigerant level and oil in the evaporator.

A plate heat exchanger includes: a plurality of heat transfer plates including first to fourth through-holes to extend through the heat transfer plate, stacked in a single direction to isolate first and second water flow passages; and end plates including first and second inlet and outlet ports, and a connection port, that the heat transfer plates are sandwiched between The first inlet and outlet port, continuous with the first and second through-holes, allow a first fluid to flow into and out of the first flow passage. The second inlet and outlet port, continuous with the third and fourth through-holes, allow a second fluid to flow into and out of the second flow passage. The connection port is connected to a pressure relief valve provided separately from the plate heat exchanger.

A heat pump may include a compressor configured to compress a refrigerant, a first temperature sensor provided in heating pipes connected to a heating device that heats an indoor space to sense a temperature of fluid flowing through the heating pipes, and a controller. The controller may be configured to determine whether a boiler is operating to heat an indoor space or is operating to supply hot water based on a sensing value of the first temperature sensor. The compressor may operate when the controller determines that the boiler is not operating to heat the indoor space and/or determines that the boiler is operating to supply hot water.

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.

A cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.

An air-conditioning apparatus includes: a plurality of outdoor units each including a compressor and an outdoor heat exchanger, refrigerant flowing through the plurality of outdoor units; an indoor unit including an indoor heat exchanger, a heat medium flowing through the indoor unit; a plurality of relay devices to which the plurality of outdoor units are connected independently, and to which the indoor unit is connected, each of the plurality of relay devices including a heat medium heat exchanger configured to exchange heat between the refrigerant and the heat medium; and a controller configured to control action of the plurality of outdoor units, the indoor unit, and the plurality of relay devices, wherein the controller includes a defrost determination unit configured to determine necessity for a defrosting operation, a load determination unit configured to compare, in a case where the defrosting operation is necessary, an indoor unit total load with an outdoor unit total capacity, and an equipment control unit configured to control an operating frequency of the compressor of an outdoor unit other than the outdoor unit on which the defrosting operation is to be performed such that the outdoor unit total capacity is increased in a case where the indoor unit total load is greater than the outdoor unit total capacity.

A method of determining charge loss of a refrigeration system includes the steps of inputting an ambient temperature, a box temperature, and a compressor speed into an electronic controller of the refrigeration system, and calculating a first air side temperature difference across an evaporator by applying an algorithm having a first T-Map representative of normal operating conditions. The controller may then confirm a detection prerequisite is satisfied. Upon confirmation, the controller calculates a second air side temperature difference across the evaporator by applying the algorithm having a second T-Map representative of a loss of refrigerant charge. An action may then be taken from the controller if the first air side temperature difference is less than the second air side temperature difference.