From: vaughnsimon@gmail.invalid   
      
   "Rick"  wrote in message news:j9ral4$10g$1@dont-email.me...   
   > "The Stirling engine is noted for its high efficiency compared to steam   
   > engines...   
      
   In theory perhaps, but I really wonder if that is true in real life.   
      
   >, ...quiet operation, and the ease with which it can use almost any heat   
   >source.   
      
   True, but the Stirling has a low power density, which means it gets very big to   
   produce significant amounts of power.  This is especially true is a low-grade   
   heat source is used because the heat transfer surfaces must become very large.   
   The Stirling engine is almost 200 years old, yet I have never seen one.  There   
   are multiple reason why they have neve become common.  .   
      
   Vaughn   
      
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