The purpose of the present invention is to achieve stable operation when using a low pressure, low GWP refrigerant. In the present invention, a control device (16) is provided with an estimation unit (31), a determination unit (32), and an activation control unit (33). The estimation unit (31) estimates the amount of air entering using a degree of influence of air entering, which represents the ease with which air enters determined by the structure of the chiller, and a variable obtained by a function including pressure as a parameter. The determination unit (32) determines whether a total value for the amount of air entering is greater than or equal to a preset tolerance value. The activation control unit (33) activates a bleed device when the total value of the amount of air entering is equal to or greater than the tolerance value.

A refrigeration circuit comprises in the direction of flow of a refrigerant at least one compressor; at least one heat rejecting heat exchanger; at least one expansion device; and at least one evaporator. The refrigeration circuit further comprises at least one heat recovery heat exchanger having a refrigeration circuit side and heat recovery system side and being configured for transferring heat between the refrigeration circuit side and the heat recovery system side, wherein the refrigeration circuit side is fluidly connected in parallel to the at least one heat rejecting heat exchanger; and at least one regulation valve, configured for regulating the flow of refrigerant flowing through the refrigeration circuit side of the at least one heat recovery heat exchanger. The at least one regulation valve is switchable between an open position, a closed position, and at least one intermediate position.

A heat pump system includes a heat source unit having a variable-capacity compressor and a heat-source-side heat exchanger that functions as an evaporator for a refrigerant, and a plurality of usage units connected to the heat source unit and having usage-side heat exchangers that function as radiators for the refrigerant. The operating capacity of the compressor is controlled to bring the discharge pressure of the compressor, or a state quantity equivalent to the discharge pressure, to a first target value. The first target value is determined based on an equivalent target value equivalent to a usage temperature required in individual usage units.

A heat-pump circuit may include an indoor heat exchanger, an outdoor heat exchanger, a compressor adapted to circulate a working fluid between the indoor and outdoor heat exchangers, and an expansion device disposed between the indoor and outdoor heat exchangers. A monitor for the heat-pump system may include a return-air temperature sensor, a supply-air temperature sensor, and a processor. The return-air temperature sensor may be adapted to measure a first air temperature of air upstream of the indoor heat exchanger. The supply-air temperature sensor may be adapted to measure a second air temperature of air downstream of the indoor heat exchanger. The processor may be in communication with the return-air temperature sensor and the supply-air temperature sensor. The processor may be programmed to determine a working-fluid-charge condition of the heat-pump system based on the first and second air temperatures.

Systems, apparatus and methods for operating a chiller plant while minimizing or eliminating the occurrence of centrifugal compressor surge. Taking into account chiller design specifications and current operating conditions, a compressor lift point at which surge is predicted to occur is established. Minima and maxima for various chiller setpoints that avoid or eliminate the occurrence of compressor surge are imposed on setpoints provided by a conventional optimizing chiller controller. The chiller system is operated in accordance with the resultant anti-surge setpoints. Coolant tower flow is modulated to enable the compressor to operate at near-surge conditions while preventing the onset of actual surge.

A two-stage pressure buildup refrigeration cycle apparatus has a low-pressure side compressor, a high-pressure side compressor, and a controller. The controller controls, for improving a COP, the low-pressure side compressor and the high-pressure side compressor in a COP improving operation mode in which a refrigerant discharge capacity of one of the low-pressure side compressor and the high-pressure side compressor is set based on a refrigerant discharge capacity of an other of the low-pressure side compressor and the high-pressure side compressor, when a required level of a refrigeration performance is low. The controller controls the low-pressure side compressor and the high-pressure side compressor in a high performance operation mode in which a refrigerant discharge capacity of the high-pressure side compressor is increased after increasing a refrigerant discharge capacity of the low-pressure side compressor, when the required level of the refrigeration performance is high.

A controller performs a first operation in which a heat source device directly or indirectly heats water in a first channel of a heat exchanger and a second operation in which the heat source device directly or indirectly cools the water in the first channel of the heat exchanger after the first operation ends.

An air conditioning apparatus includes, a first heat exchanger, a second heat exchanger configured to exchange heat between a first heat medium and a second heat medium, flow rate control valves, and a pump. In a heating mode, a controller is configured to open the flow rate control valve corresponding to a heat exchanger, of the third heat exchangers, to which a request for air conditioning has been made, and to close the flow rate control valve(s) corresponding to a heat exchanger(s), of the third heat exchangers, to which the request for air conditioning has not been made. In a defrosting mode, when a temperature of the second heat medium is lower than a first determination temperature, the controller is configured to open at least one of the flow rate control valve(s) corresponding to the heat exchanger(s) to which the request for air conditioning has not been made.

A water dispensing system includes a faucet, a sink basin mounted beneath the faucet downstream therefrom, a first storage tank mounted below the sink basin to store a first liquid volume, a second storage tank mounted below the sink basin to store a second liquid volume, and a vapor compression system including a compressor, an evaporator in fluid communication with the compressor, the evaporator being connected to the first storage tank in conductive thermal communication, a condenser in fluid communication with the compressor, the condenser being connected to the second storage tank in conductive thermal communication, and an expansion device in fluid communication with the compressor.

A refrigeration system includes a receiver, a gas bypass valve, a parallel compressor, and a controller. The gas bypass valve and the parallel compressor are fluidly coupled to an outlet of the receiver in parallel and configured to control a pressure of a gas refrigerant in the receiver. The controller is configured to switch from operating the gas bypass valve to operating the parallel compressor to control the pressure of the gas refrigerant in the receiver in response to a value of a process variable crossing a switchover setpoint. The value of the process variable depends on an amount of the gas refrigerant produced by the refrigeration system. The controller is configured to automatically adjust the switchover setpoint in response to the amount of the gas refrigerant produced by the refrigeration system being insufficient to sustain operation of the parallel compressor.