One or more outlet apertures are formed between the two inner shells for {HEAD ~ passage} of the gaseous fluid out of {TAIL ~ the heat} exchanging chamber 
out of
One or more outlet apertures are formed between the two inner shells for { HEAD ~ passage } of the gaseous fluid out of { TAIL ~ the heat } exchanging chamber
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH