Cooling device and control method for cooling device

Abstract

A cooling device using a refrigeration cycle in which a refrigerant is circulated through a heat receiver, a compressor, a heat radiator, and an expansion valve includes: a gas-liquid separator configured to perform gas-liquid separation on the refrigerant supplied from the expansion valve; a pump configured to send a liquid phase refrigerant separated by the gas-liquid separator to the heat receiver; and a control unit configured to control opening and closing of a refrigerant flow path of the refrigeration cycle, and an operation and stop of the compressor and the pump, wherein the control unit starts the operation of the pump on condition that a net positive suction head of the pump has reached a predetermined value or more.

What is claimed is: 
     
         1 . A cooling device using a refrigeration cycle in which a refrigerant is circulated through a heat receiver, a compressor, a heat radiator, and an expansion valve, the cooling device comprising:
 a gas-liquid separator configured to perform gas-liquid separation on the refrigerant supplied from the expansion valve;   a pump configured to send a liquid phase refrigerant separated by the gas-liquid separator to the heat receiver; and   a control unit configured to control opening and closing of a refrigerant flow path of the refrigeration cycle, and an operation and stop of the compressor and the pump,   wherein the control unit starts the operation of the pump on condition that a net positive suction head of the pump has reached a predetermined value or more, and   wherein the control unit calculates the net positive suction head from detection data of a pressure sensor and a temperature sensor, the pressure sensor being configured to measure a pressure of a liquid phase portion between the pump and the gas-liquid separator and inside a bypass valve pipe configured to connect a front and a rear of the pump, the temperature sensor being configured to measure a temperature of the refrigerant.   
     
     
         2 . The cooling device according to  claim 1 , wherein the control unit calculates the net positive suction head using a pressure between the pump and the gas-liquid separator, a saturated vapor pressure of the refrigerant, and a liquid density of the refrigerant. 
     
     
         3 . The cooling device according to  claim 1 , wherein the control unit calculates the net positive suction head from detection data of a pressure sensor and a temperature sensor, the pressure sensor being configured to measure a pressure of a liquid phase portion between the pump and the gas-liquid separator, the temperature sensor being configured to measure a temperature of the refrigerant. 
     
     
         4 . (canceled) 
     
     
         5 . The cooling device according to  claim 1 , wherein the control unit calculates the net positive suction head using a liquid level height inside the gas-liquid separator, a pressure of a gas phase portion, a saturated vapor pressure of the refrigerant, and a density of the refrigerant. 
     
     
         6 . The cooling device according to  claim 1 , wherein the control unit calculates the net positive suction head from detection data of a liquid level sensor, a pressure sensor and a temperature sensor, the liquid level sensor being configured to measure a liquid level of the gas-liquid separator, the pressure sensor being configured to measure a pressure of a gas phase portion of the gas-liquid separator, the temperature sensor being configured to measure a temperature of the refrigerant in the gas-liquid separator. 
     
     
         7 . The cooling device according to  claim 1 , wherein the control unit starts an operation of the pump on condition that a predetermined time has elapsed after activation of the compressor. 
     
     
         8 . A control method for a cooling device using a refrigeration cycle in which a refrigerant is circulated through a heat receiver, a compressor, a heat radiator, and an expansion valve, the control method comprising:
 controlling, by a control unit, an operation of a pump configured to send, to the heat receiver, a liquid phase refrigerant separated by a gas-liquid separator configured to perform gas-liquid separation on the refrigerant supplied from the expansion valve;   starting, by the control unit, the operation of the pump on condition that a net positive suction head of the pump has reached a predetermined value or more; and   calculating, by the control unit, the net positive suction head from detection data of a pressure sensor and a temperature sensor, the pressure sensor being configured to measure a pressure of a liquid phase portion between the pump and the gas-liquid separator and inside a bypass valve pipe configured to connect a front and a rear of the pump, the temperature sensor being configured to measure a temperature of the refrigerant.