The variable cross sectional vapor passage first increases and then decreases {HEAD ~ the rate} of {TAIL ~ vapor flow}, and a further heat transfer zone with either heat supply or removal is located in the area of increased vapor velocity 
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The variable cross sectional vapor passage first increases and then decreases { HEAD ~ the rate } of { TAIL ~ vapor flow } , and a further heat transfer zone with either heat supply or removal is located in the area of increased vapor velocity
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH