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