{HEAD ~ The first and second heat exchange chambers} respectively are labelled as {TAIL ~ the high and low temperature chambers} 
are labelled as
{ HEAD ~ The first and second heat exchange chambers } respectively are labelled as { TAIL ~ the high and low temperature chambers }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL