Leak detection with thermal imaging

Abstract

An infrared camera is used to detect leakages in a heat exchanger by an imaging process that indicates temperature differences between a heat exchanger and a pressurized gas therein. The temperature differences are created by cooling or heating either the pressurized gas or the heat exchanger, and any leakages are visually observable by the resultant image which is representative of the temperature differences. The process can be accomplished with the use of ambient air rather than the commonly used trace gases which are less desirable because of economical and environmental reasons.

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       19 . A method of detecting leaks in heat exchanger of the type having an internal conduit through which refrigerant is intended to pass for purposes of heat transfer between the refrigerant and a medium passing externally over said heat exchanger, comprising the steps of: 
 pressurizing said heat exchanger with a vapor which is at a different temperature from that of the heat exchanger; and    exposing areas of the heat exchanger to a temperature sensitive device so as to detect leakage of said vapor from the heat exchanger.    
   
   
       20 . A method as set forth in  claim 19  wherein said vapor is a non-refrigerant.  
   
   
       21 . A method as set forth in  claim 20  wherein said vapor is ambient air.  
   
   
       22 . A method as set forth in  claim 19  and including the step of heating said heat exchanger to increase the temperature difference between said heat exchanger and vapor.  
   
   
       23 . A method as set forth in  claim 19  and including the step of cooling the heat exchanger to increase the difference between the temperatures of the heat exchanger and the vapor.  
   
   
       24 . A method as set forth in  claim 19  and including the step of positioning a black body behind the heat exchanger to reduce the error that would otherwise occur by reflection of light to a temperature sensitive device.  
   
   
       25 . A method as set forth in  claim 19  wherein said temperature sensitive device is an infrared camera.  
   
   
       26 . A method as set forth in  claim 25  and including the further steps of generating signals of the respective temperatures and responsively constructing an image representative thereof.