Cooling system and method for operating same

Abstract

An air conditioning system for appropriately controlling the air conditioning capacity by preventing occurrence of cavitation of a refrigerant pump and a method of operating the system are provided. It includes an evaporator for vaporizing a refrigerant by exchanging heat with air in a room to be air-conditioned, a condenser for liquefying a refrigerant gas vaporized by the evaporator, a refrigerant pump for feeding a refrigerant liquid liquefied by the condenser to the evaporator, a refrigerant liquid tank disposed between the condenser and the refrigerant pump to temporarily store the refrigerant liquid liquefied by the condenser, first cold water piping for supplying cold water generated from a heat source machine to the condenser, second cold water piping for supplying the cold water generated from the heat source machine to the refrigerant liquid tank, a refrigerant liquid temperature sensor for measuring a temperature of the refrigerant liquid in the refrigerant liquid tank and a control unit for controlling to supply the cold water desired for condensation of the refrigerant gas to the condenser.

1 . An air conditioning system comprising:
 an evaporator for vaporizing a refrigerant by exchanging heat between the refrigerant and air in a room to be air-conditioned;   a condenser for liquefying a refrigerant gas vaporized by the evaporator;
 a refrigerant pump for feeding a refrigerant liquid liquefied by the condenser to the evaporator; 
 a refrigerant liquid tank disposed between the condenser and the refrigerant pump to temporarily store the refrigerant liquid liquefied by the condenser; and 
   first cold water piping for supplying cold water generated from a heat source machine to the condenser,   and further comprising:   second cold water piping for supplying the cold water generated from the heat source machine to the refrigerant liquid tank;   a refrigerant liquid temperature sensor for measuring a temperature of the refrigerant liquid in the refrigerant liquid tank; and   a control unit for controlling to supply the cold water desired for condensation of the refrigerant gas to the condenser.   
     
     
         2 . The air conditioning system according to  claim 1 , wherein
 the first cold water piping is series-connected with the second cold water piping to flow the cold water from the heat source machine to the condenser and the refrigerant liquid tank in series.   
     
     
         3 . The air conditioning system according to  claim 2 , wherein
 the first cold water piping is connected with the second cold water piping such that the cold water flows from the heat source machine to the condenser via the refrigerant liquid tank.   
     
     
         4 . The air conditioning system according to  claim 1 , further comprising:
 pressure sensors for measuring a discharge pressure and a suction pressure of the refrigerant pump; and   an inverter for changing an operating frequency of the refrigerant pump,   wherein the operating frequency of the refrigerant pump is controlled by the control unit such that a differential pressure between the discharge pressure and the suction pressure has a set value.   
     
     
         5 . The air conditioning system according to  claim 1 , further comprising:
 a zero point temperature detection unit for detecting a zero point temperature in the room to be air-conditioned; and   a condensate temperature sensor for measuring a temperature of the refrigerant liquid liquefied by the condenser,   wherein when the temperature of the refrigerant liquid in the refrigerant liquid tank is lower than the zero point temperature detected by the zero point temperature detection unit, the flow rate of the cold water into the refrigerant liquid tank is adjusted such that the temperature of the refrigerant liquid in the refrigerant liquid tank becomes higher than the zero point temperature in the room and the flow rate of the cold water into the condenser is adjusted such that the temperature of the liquefied refrigerant in the condenser becomes higher than the temperature of the refrigerant liquid in the refrigerant liquid tank by the control unit.   
     
     
         6 . The air conditioning system according to  claim 1 , wherein
 an evaporating temperature is calculated from the suction pressure of the refrigerant pump and the cold water is supplied to the refrigerant liquid tank such that the temperature of the refrigerant liquid in the refrigerant liquid tank becomes lower than the calculated evaporating temperature by the control unit.   
     
     
         7 . A method of operating an air conditioning system comprising:
 an evaporator for vaporizing a refrigerant by exchanging heat between the refrigerant and air in a room to be air-conditioned;   a condenser for liquefying a refrigerant gas vaporized by the evaporator;   a refrigerant pump for feeding a refrigerant liquid liquefied by the condenser to the evaporator;   a refrigerant liquid tank disposed between the condenser and the refrigerant pump to temporarily store the refrigerant liquid liquefied by the condenser; and   cold water piping for supplying cold water generated from a heat source machine to the condenser and the refrigerant liquid tank, and   controlling the operations of the above components by a control unit,   wherein cold water desired for condensation of the refrigerant is supplied to the condenser.   
     
     
         8 . The method of operating the air conditioning system according to  claim 7 , wherein
 the cold water piping for supplying the cold water to the condenser is series-connected with the cold water piping for supplying the cold water to the refrigerant liquid tank to flow the cold water from the heat source machine to the condenser and the refrigerant liquid tank in series.   
     
     
         9 . The method of operating the air conditioning system according to  claim 8 , wherein
 the cold water is supplied from the heat source machine to the condenser via the refrigerant liquid tank.   
     
     
         10 . The method of operating the air conditioning system according to  claim 7 , wherein
 a discharge pressure and a suction pressure of the refrigerant pump are measured and an operating frequency of the refrigerant pump is controlled such that a differential pressure between the discharge pressure and the suction pressure has a set value.   
     
     
         11 . The method of operating the air conditioning system according to  claim 7 , further comprising:
 a zero point temperature detection unit for detecting a zero point temperature in the room to be air-conditioned; and   a condensate temperature sensor for measuring a temperature of the refrigerant liquid liquefied by the condenser,   wherein when the temperature of the refrigerant liquid in the refrigerant liquid tank is lower than the zero point temperature detected by the zero point temperature detection unit, the flow rate of the cold water into the refrigerant liquid tank is adjusted such that the temperature of the refrigerant liquid in the refrigerant liquid tank becomes higher than the zero point temperature in the room, and the flow rate of the cold water into the condenser is adjusted such that the temperature of the liquefied refrigerant in the condenser becomes higher than the temperature of the refrigerant liquid in the refrigerant liquid tank.   
     
     
         12 . The method of operating the air conditioning system according to  claim 7 , wherein
 an evaporating temperature is calculated from the suction pressure at an inlet of the refrigerant pump and the cold water is supplied to the refrigerant liquid tank such that the temperature of the refrigerant liquid in the refrigerant liquid tank becomes lower than the calculated evaporating temperature.