The coolant is introduced into {HEAD ~ the channels} co currently with the direction of flow of {TAIL ~ the reactants} 
The coolant is introduced into { HEAD ~ the channels } co currently with the direction of flow of { TAIL ~ the reactants }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL