A method of initiating a low-energy cooling mode using a controller of an HVAC system includes measuring a temperature of ambient air proximal to a condenser coil and determining whether the temperature of the ambient air proximal the condenser coil is less than a temperature threshold. If the temperature of the ambient air is less than the temperature threshold, the HVAC system is configured to operate in a low-energy cooling mode. In the low-energy cooling mode, the controller opens a first bypass valve to allow a refrigerant to bypass a compressor and the compressor is powered off. The HVAC system is operated until a cooling demand has been met.

A cooling system includes a heat exchanger through which a refrigerant flows, the heat exchanger having a fluid passing therethrough such that heat is rejected to the fluid, an evaporator, a refrigerant piping split point that receives the refrigerant at a given pressure from the heat exchanger and splits the refrigerant flow into a first circuit and a second circuit, the first circuit having an expansion valve that receives the refrigerant at the given pressure, and the second circuit having a first turbine coupled to a first compressor, wherein the first turbine receives the refrigerant at the given pressure, and a set of valves arranged to direct the refrigerant through the first circuit, the second circuit, or both the first and second circuits based on ambient conditions of the cooling system.

A device for controlling the temperature of an external fluid. The device including a compressor for compressing an internal fluid, a first heat exchanger in a temperature control circuit for transferring thermal energy between the internal fluid and the external fluid. The device is further configured for use within a system for controlling the temperature of blood.

A cooling system includes: a local cooler that is positioned near a server serving as a heat source and that evaporates a refrigerant by directly receiving heat from the server to generate a gas-phase refrigerant; a compressor that compresses the gas-phase refrigerant; an outdoor unit that condenses the gas-phase refrigerant supplied from the compressor by dissipating heat from the gas-phase refrigerant; an expansion valve that depressurizes the refrigerant supplied from the outdoor unit and sends the refrigerant to the local cooler; a pair of detectors that are respectively provided at an inlet side and an outlet side of the compressor and detect a state of the gas-phase refrigerant supplied from the local cooler; and a proportional control valve and a high-speed on-off valve that are operated based on a refrigerant state ratio calculated from a detection value of the detectors.

A cooling system includes: a local cooler that is positioned near a heat source and evaporates a liquid-phase refrigerant by receiving heat from the heat source; a turbo compressor that compresses a gas-phase refrigerant that absorbed the heat in the local cooler; an outdoor unit that condenses the gas-phase refrigerant supplied from the turbo compressor by heat dissipation; and an expansion valve that depressurizes the refrigerant supplied from the outdoor unit and sends the refrigerant to the local cooler. The refrigerant is a low-pressure refrigerant having a condensing pressure lower than a predetermined value.

A method of initiating a low-energy cooling mode using a controller of an HVAC system includes measuring a temperature of ambient air proximal to a condenser coil and determining whether the temperature of the ambient air proximal the condenser coil is less than a temperature threshold. If the temperature of the ambient air is less than the temperature threshold, the HVAC system is configured to operate in a low-energy cooling mode. In the low-energy cooling mode, the controller opens a first bypass valve to allow a refrigerant to bypass a compressor and the compressor is powered off. The HVAC system is operated until a cooling demand has been met.

During a first cooling operation, a compressor is in an operational state, a liquid pump is in a non-operational state, and an amount of refrigerant allowing for existence of a liquid surface of the refrigerant in a refrigerant tank is accumulated in the refrigerant tank. During a second cooling operation, the compressor is in the non-operational state, the liquid pump is in the operational state, and the amount of the refrigerant allowing for the liquid surface of the refrigerant in the refrigerant tank is accumulated in the refrigerant tank.

An outdoor expansion valve is provided for a liquid side pipe of an outdoor circuit. The outdoor circuit is provided with a liquid side bypass pipe that allows the liquid side pipe to communicate with a suction side of a compressor. Receiving a signal indicating that a refrigerant has leaked from an indoor circuit, an outdoor controller executes a refrigerant recovery control operation of operating the compressor with a liquid side control valve closed, and executes a valve control operation of opening a liquid side bypass valve of the liquid side bypass pipe in the refrigerant recovery control operation. As a result, the refrigerant can be recovered from an utilization-side circuit to a heat-source-side circuit while avoiding damage to the compressor, and the amount of refrigerant leaking from the utilization-side circuit can be reduced.

An air conditioner system is disclosed. The air conditioner system includes: a compressor; a four-way valve configured to provide a refrigerant circulation path depending on an operation mode of the air conditioner system; a blocking valve disposed between the compressor and the four-way valve; a circulation line configured to provide a path for introducing a refrigerant discharged from the compressor back into the compressor, when the blocking valve is in a closed state; and a controller configured to control the blocking valve based on a pressure of the refrigerant discharged from the compressor.

A refrigeration system includes a high-pressure side scroll compressor having a primary suction port and an intermediate suction port, an evaporator having an inlet and an outlet, a primary compressor inlet flow path fluidly coupling the outlet of the evaporator with both the primary suction port and the intermediate suction port, and a control valve operable to direct a flow of fluid moving along the primary compressor inlet flow path to at least one of the primary suction port to the intermediate suction port in response to a mode of operation of the refrigeration system. A capacity of the compressor associated with the primary suction port is greater than a capacity of the compressor associated with the intermediate suction port.