Then {HEAD ~ the refrigerant} flows downwardly through {TAIL ~ header} 54 and enters the two tubes forming the second tube circuit 32b arranged in series with the upper tube circuit 32a 
flows downwardly through
Then { HEAD ~ the refrigerant } flows downwardly through { TAIL ~ header } 54 and enters the two tubes forming the second tube circuit 32b arranged in series with the upper tube circuit 32a
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL 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