The direction of {HEAD ~ flow} of {TAIL ~ liquid} through the shell 12, however, has no effect on efficiency and so does not matter 
of
The direction of { HEAD ~ flow } of { TAIL ~ liquid } through the shell 12 , however , has no effect on efficiency and so does not matter
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH