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