Supplemental heating for variable load evaporative cold plates

Abstract

Supplemental heat mechanisms are employed to ensure that refrigerant in evaporative cold plates for electronic modules not only returns to the compressor in a vapor phase but also further operates to maintain electronic circuit junction temperatures at relatively constant temperature levels. Furthermore, the supplemental heating system responds within a time frame which is faster than other methods which may be employed to achieve the same or similar objectives. In particular, in preferred embodiments of the present invention pressure and temperature measurements of refrigerant exiting the evaporative cold plate are employed to control the turning on of supplemental electrical resistive heating elements to make up for thermal dissipation fluctuations occurring in the electronic module. The supplemental heat may be provided either with a single flat element or through the use of in-line heating elements. The supplemental heating mechanism provides a method for insuring that refrigerant material is returned to the compressor in a vapor state so as to particularly not adversely affect compressor life and/or operating efficiency.

What is claimed is:  
     
         1 . An electronic system with cooling for variable thermal load levels, said system comprising: 
 an electronic circuit module;    a cold plate in thermal contact with said module, said cold plate having at least one passage therein for transport of refrigerant;    means for sensing power being supplied to said module;    at least one in-line heater surrounding at least one conduit for carrying said refrigerant;    means for controlling said in-line heater to compensate for changes in said power being supplied to said module, so as to maintain a relatively constant cooling load for said refrigerant.    
     
     
         2 . The system of    claim 1    in which said cold plate has dual passages therein for distinct refrigerant loops.  
     
     
         3 . The system of    claim 1    in which said sensing means is a temperature sensor disposed in thermal contact with said module.  
     
     
         4 . The system of    claim 1    in which said sensing means comprises pressure and temperature sensors for said refrigerant.  
     
     
         5 . The system of    claim 4    in which said pressure and temperature sensing means is located substantially immediately downstream of said cold plate.  
     
     
         6 . The system of    claim 1    in which said cold plate includes a plurality of passages therein.  
     
     
         7 . The system of    claim 1    in which said in-line heater is located downstream of said cold plate.  
     
     
         8 . The system of    claim 1    in which said in-line heater is located upstream of said cold plate.  
     
     
         9 . The system of    claim 1    in which a single in-line heater surrounds a plurality of conduits for carrying said refrigerant.  
     
     
         10 . The system of    claim 1    in which a plurality of in-line heaters each surround one conduit for carrying said refrigerant.