Economizer cooling temperature protection

Abstract

A cooling loop can include a heat exchanger for transferring heat from a heat source to a cooling fluid, a compressor for selectively compressing a vaporized portion of the cooling fluid, a condenser for rejecting heat from the cooling fluid, a pump for selectively pumping the cooling fluid through the loop, and a controller. The controller can operate the pump to pump the cooling fluid through the loop when the measured temperature is less than a first offset temperature, continue operating the pump to pump the cooling fluid through the loop for a time period when the measured temperature reaches a first offset temperature, and deactivate the pump and initiate operation of the compressor before the measured temperature exceeds a second offset temperature.

What is claimed is: 
     
         1 . A cooling loop comprising: 
 a heat exchanger configured to transfer heat from a heat source to a cooling fluid;   a compressor configured to selectively compress a vaporized portion of the cooling fluid and circulate the cooling fluid through the loop;   a condenser configured to reject heat from the cooling fluid;   a pump configured to selectively pump the cooling fluid through the loop; and   a controller configured to: 
 monitor a setpoint temperature, a measured temperature, a first time period, a first offset temperature and a second offset temperature, wherein the first offset temperature and the second offset temperature are greater than the setpoint temperature, and wherein the second offset temperature is greater than the first offset temperature; 
 operate the pump to pump the cooling fluid through the loop when the measured temperature is less than the first offset temperature; 
 when the measured temperature reaches the first offset temperature, continue operating the pump to pump the cooling fluid through the loop for the first time period; and 
 deactivate the pump and initiate operation of the compressor before the measured temperature exceeds the second offset temperature. 
   
     
     
         2 . The cooling loop as set forth in  claim 1 , wherein the controller is further configured to deactivate the pump and initiate operation of the compressor before the measured temperature reaches the second offset temperature. 
     
     
         3 . The cooling loop as set forth in  claim 1 , wherein the controller is further configured to monitor a second time period and a third offset temperature, wherein the second time period is less than the first time period; and wherein the controller is configured to deactivate the pump and initiate operation of the compressor if the measured temperature is greater than or equal to the third offset temperature when the second time period has elapsed. 
     
     
         4 . The cooling loop as set forth in  claim 3 , wherein the third offset temperature is greater than or equal to the second offset temperature. 
     
     
         5 . The cooling loop as set forth in  claim 1 , wherein the controller is configured to deactivate the pump and initiate operation of the compressor upon conclusion of the first time period and regardless of whether the measured temperature is greater than or equal to the first offset temperature when the first time period has elapsed. 
     
     
         6 . The cooling loop as set forth in  claim 1 , wherein the first time period is a predetermined period of time configured to allow the measured temperature to exceed the first offset temperature and prevent the measured temperature from exceeding the second offset temperature. 
     
     
         7 . A method of operating a cooling loop having a compressed refrigerant mode and a pumped refrigerant mode, the method comprising: 
 operating the loop in the pumped refrigerant mode when a cooling demand is less than a threshold, wherein operating the loop in the pumped refrigerant mode comprises allowing a temperature to vary within a first range;   operating the loop in the compressed refrigerant mode when the cooling demand is greater than the threshold, wherein operating the loop in the compressed refrigerant mode comprises allowing the temperature to vary within a second range, wherein the second range is wider than the first range; and   switching from the pumped refrigerant mode to the compressed refrigerant mode when the temperature meets or exceeds a limit.   
     
     
         8 . The method as set forth in  claim 7 , wherein switching from the pumped refrigerant mode to the compressed refrigerant mode comprises switching from the pumped refrigerant mode to the compressed refrigerant mode when the temperature meets or exceeds the limit and a delay period has expired. 
     
     
         9 . The method as set forth in  claim 8 , wherein the delay period is measured from the temperature exceeding the limit. 
     
     
         10 . The method as set forth in  claim 8 , wherein the limit is a first limit, wherein the delay period is configured to prevent the temperature from meeting or exceeding a second limit before switching from the pumped refrigerant mode to the compressed refrigerant mode, and wherein the second limit is higher than the first limit. 
     
     
         11 . The method as set forth in  claim 7 , wherein switching from the pumped refrigerant mode to the compressed refrigerant mode comprises switching from the pumped refrigerant mode to the compressed refrigerant mode when the temperature exceeds the limit and a predetermined period of time has elapsed. 
     
     
         12 . The method as set forth in  claim 8 , wherein switching from the pumped refrigerant mode to the compressed refrigerant mode comprises switching from the pumped refrigerant mode to the compressed refrigerant mode regardless of the cooling demand. 
     
     
         13 . The method as set forth in  claim 12 , further including delaying switching back to the pumped refrigerant mode from the compressed refrigerant mode for a delay period. 
     
     
         14 . The method as set forth in  claim 7 , wherein switching from the pumped refrigerant mode to the compressed refrigerant mode comprises switching from the pumped refrigerant mode to the compressed refrigerant mode when the temperature exceeds the limit and the cooling demand is greater than the threshold. 
     
     
         15 . A method of operating a cooling loop having a compressed refrigerant mode and a pumped refrigerant mode, the method comprising: 
 monitoring a setpoint temperature, a measured temperature, a first time period, a first offset temperature and a second offset temperature, wherein the first offset temperature and the second offset temperature are greater than the setpoint temperature, and wherein the second offset temperature is greater than the first offset temperature;   operating the loop in the pumped refrigerant mode when the measured temperature is less than the first offset temperature;   when the measured temperature reaches the first offset temperature, continuing to operate the loop in the pumped refrigerant mode for the first time period; and   switching from the pumped refrigerant mode to the compressed refrigerant mode before the measured temperature exceeds the second offset temperature.   
     
     
         16 . The method as set forth in  claim 15 , further comprising switching from the pumped refrigerant mode to the compressed refrigerant mode before the measured temperature reaches the second offset temperature. 
     
     
         17 . The method as set forth in  claim 15 , further comprising monitoring a second time period and a third offset temperature, wherein the second time period is less than the first time period; and switching from the pumped refrigerant mode to the compressed refrigerant mode if the measured temperature is greater than or equal to the third offset temperature when the second time period has elapsed. 
     
     
         18 . The method as set forth in  claim 17 , wherein the third offset temperature is greater than or equal to the second offset temperature. 
     
     
         19 . The method as set forth in  claim 15 , further comprising switching from the pumped refrigerant mode to the compressed refrigerant mode upon conclusion of the first time period and regardless of whether the measured temperature is greater than or equal to the first offset temperature when the first time period has elapsed. 
     
     
         20 . The method as set forth in  claim 15 , wherein the first time period is a predetermined period of time configured to allow the measured temperature to exceed the first offset temperature and prevent the measured temperature from exceeding the second offset temperature.