A part of {HEAD ~ the heated air} is used as {TAIL ~ the heated air} for drying and the other is exhausted to the open air 
A part of { HEAD ~ the heated air } is used as { TAIL ~ the heated air } for drying and the other is exhausted to the open air
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH