A temperature control system is disclosed where thermal energy generated by pressurization of a gaseous medium is stored at a selected temperature level so that it is later readily accessible. Temperature control of a two-phase medium is exercised across selectable dynamic ranges and with different resolutions and the control can be exerted by varying the input flow rate of a mixture applied to a thermal load, or by controlling the back pressure of the flow through the thermal load.

A compressed vaporous discharge stream is de-superheated in a de-superheater system. The de-superheater system comprises a de-superheater heat exchanger configured to bring at least a portion of the compressed vaporous discharge stream in indirect heat exchanging contact with an ambient stream. A de-superheater bypass line comprising an temperature-controlled valve is configured to selectively bypass the de-superheater heat exchanger. A combiner is configured downstream of the de-superheater heat exchanger for rejoining the bypass portion with the portion of the compressed vaporous discharge stream that has passed through the de-superheater heat exchanger. A mixer is configured downstream of said combiner, to receive and mix the rejoined stream, and discharge the rejoined stream into a de-superheater discharge conduit as a de-superheated stream.

A refrigeration system includes a heat exchanger configured to provide superheat control for the low temperature low pressure gas refrigerant flowing out of the evaporator and through the first side of the heat exchanger by transferring heat from the high pressure high temperature superheated gas refrigerant flowing through a second side of the heat exchanger. A modulating solenoid valve is located at the inlet of the second side of the heat exchanger and configured to modulate the flow of high pressure high temperature superheated gas refrigerant flowing through the second side of the heat exchanger. A temperature sensor is located in such a way as to measure the temperature of the gas refrigerant flowing out of the evaporator and through the first side of the heat exchanger. A controller is configured to calculate the superheat of the gas refrigerant based on the measured temperature and measured pressure of the gas refrigerant and may compare the calculated superheat to a superheat threshold. If the calculated superheat is less than the superheat threshold, the controller will modulate the flow the high pressure high temperature gas refrigerant flowing through the second side of the heat exchanger. The refrigeration system may be activated in a variety of methods by appropriate control of the valves and other system components.

A notifier notifies a user of a warning when a ratio of first refrigerant is different from a suitable value, the ratio being determined from a first difference between a first temperature and a second temperature and from a second difference between a third temperature and a fourth temperature. The first temperature is a temperature of non-azeotropic refrigerant mixture between first heat exchanger and a second heat exchanger. The second temperature is a temperature of the non-azeotropic refrigerant mixture between the second heat exchanger and first expansion valve. The third temperature is a temperature of the non-azeotropic refrigerant mixture between a first decompressor and first connecting point. The fourth temperature is a temperature of the non-azeotropic refrigerant mixture between a second decompressor and the first connecting point.

An air conditioner includes: a cooling unit having a compressor operated at a variable operating frequency to adjust a revolving speed thereof, a condenser, an expansion valve and a cooling coil; and a heating unit for causing the heating medium flowing from the compressor toward the condenser to diverge, and to return to flow into the condenser, through a heating coil and a thermal dose adjusting valve disposed on the downstream side thereof; so as to control a temperature of air by the cooling and heating coils. When an opening manipulated variable of the thermal dose adjusting valve exceeds a first threshold value over a period of time, an operating frequency of the compressor is decreased, and when the opening manipulated variable of the thermal dose adjusting valve falls below a smaller, second threshold value, over the said period of time, the operating frequency of the compressor is increased.

An HVAC system with a reheat coil is described, the system includes a compressor, a micro-channel condenser and an evaporator. A reversing valve is connected to the compressor, the micro-channel condenser and the reheat coil. The reversing valve is used to direct the refrigerant from the compressor to the micro-channel condenser in a normal mode, and to direct the refrigerant from the compressor to the reheat coil in a reheat mode. The reversing valve can be switched from normal mode to reheat mode when a high pressure condition is detected at an input to the micro-channel condenser, and switched back from reheat mode to normal mode when the high pressure condition has resolved or an amount of time has passed. In the normal mode the refrigerant is returned from the reheat coil into a refrigerant line between the evaporator and the compressor through a restrictor.

A heat pump system may be selectively operated in a defrost mode or cycle. The system includes an energy recovery module that receives and conditions air in a regeneration air channel. A pre-processing module is positioned downstream of the energy recovery module. The pre-processing module receives and heats air from the energy recovery module. A regeneration air heat exchanger is positioned downstream of the pre-processing module. The regeneration air heat exchanger receives and conditions air from the pre-processing module. The pre-processing module heats the air from the energy recovery module to increase an efficiency of the regeneration air heat exchanger. During the defrost mode, a loop of regeneration air may be recirculated between the supply air channel and the regeneration air channel in order to defrost the regeneration air heat exchanger.

A heat recovery system arranged to heat water includes at least one heat exchanger (9) arranged to heat water by heat exchange with waste heat. A storage reservoir (11) is arranged to store water heated by the heat exchanger (9). The heat exchanger (9) is switchable between a first mode of operation in which water is circulated by a pump (12) in a circuit that includes the storage reservoir (11) and the heat exchanger (9), and a second mode of operation in which water is circulated by the pump (12) in a circuit that by-passes the heat exchanger (9). Heated water of at least a desired minimum temperature can be supplied to at least one outlet during both the first and second modes of operation.

An HVAC system is disclosed, comprising: (a) a compressor, (b) a source heat exchanger for exchanging heat with a source fluid, (c) a first load heat exchanger operable for heating/cooling air in a space, (d) a second load heat exchanger for heating water, (e) first and second reversing valves, (f) first and second 3-way valves, (f) a bi-directional electronic expansion valve, (g) a first bi-directional valve, and (h) a second bi-directional valve to modulate exchange of heat in the first load heat exchanger when operating as an evaporator and to control flashing of the refrigerant entering the source heat exchanger when operating as an evaporator, (h) a source pump for circulating the source fluid through the first load heat exchanger, (i) a water pump for circulating water through the second load heat exchanger, and (j) a controller to control operation of the foregoing.

A refrigeration apparatus includes a refrigerant circuit connecting heat-source units in parallel with usage units. First and second heat-source units have first and second compressors, first and second heat-source-side heat exchangers, first and second high-pressure receivers, first and second detecting elements detecting whether the receivers are near flooding, first and second bypass channels returning refrigerant in top parts of the receivers to intake sides of the compressors, and first and second motor-operated valves on the bypass channels, respectively. A controller performs excess refrigerant distribution control in which an opening degree of the first valve is controlled to be greater than an opening degree of the second valve when the second detecting element detects a nearly flooded state, and the opening degree of the second valve is controlled to be greater than the opening degree of the first valve when the first detecting element detects a nearly flooded state.