{HEAD ~ The tube bundle} is sealed within {TAIL ~ a shell}, which is a sealed chamber through which a working liquid, such as water, is circulated and is heated by the hot tubes 
is sealed within
{ HEAD ~ The tube bundle } is sealed within { TAIL ~ a shell } , which is a sealed chamber through which a working liquid , such as water , is circulated and is heated by the hot tubes
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL 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 OTH OTH OTH