Cooling system, surge generation prevention device, surge generation prevention method, and surge generation prevention program

A surge generation prevention device comprising:

• 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 generated in the local cooler;
• 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 of the compressor 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 provided in parallel with a bypass route of the compressor and are operated based on a refrigerant state ratio calculated from a detection value of the detectors,
• wherein the controller calculates, as the refrigerant state ratio, a state ratio of the refrigerant in a vapor pipe on an outlet side of the compressor with respect to the refrigerant in a vapor pipe on an inlet side of the compressor from the detection value of the detectors and controls the proportional control valve and the high-speed on-off valve depending on whether or not the calculated state ratio goes beyond a preset reference value.

A surge generation prevention method for a cooling system, the cooling system comprising:

• 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 generated in the local cooler;
• an outdoor unit that condenses the gas-phase refrigerant supplied from the compressor by dissipating heat from the gas-phase refrigerant;
• and an expansion valve that depressurizes the refrigerant supplied from the outdoor unit and sends the refrigerant to the local cooler, the surge generation prevention method comprising:
• detecting a state of the gas-phase refrigerant supplied from the local cooler by detectors respectively provided at an inlet side of the compressor and an outlet side of the compressor;
• calculating a state ratio of the refrigerant in a vapor pipe on the outlet side of the compressor with respect to the refrigerant in a vapor pipe on the inlet side of the compressor from a detection value of the detectors;
• adjusting an opening degree of a proportional control valve in a stepwise manner so that the calculated state ratio matches or approximates a preset standard target value, the proportional control valve being arranged in parallel with the compressor;
• and
• opening a high-speed on-off valve when the calculated state ratio goes beyond a preset upper threshold value, and closing the high-speed on-off valve when the calculated state ratio goes beyond a preset lower limit threshold value, the high-speed on-off valve being arranged in parallel with the compressor and the proportional control valve.