[Witchdoctor]

Wow Rich, I am in the industry and that is a very deep explination

When you braze you use a nitrogen purge to remove the presence of air not to burn the inside of the tubing, that causes flaking and can lead to premature compressor failure

Refrigeration loops are a simple process, it uses the latent heat energy of condinsation and evaporation hence the name Condensor and Evaporator, This is an invisible energy souce that once discoved cataplulted the refrigreation era and eliminnating the ice trucks seen in the early 1900's

Here is a very basic picture of a refrigeration loop, instead of an expansion valve most use what you would call a cap tube to meter the refrigerant, that is why many builders have to play with the length of it to maximixe efficiancy