{HEAD ~ Hydrogen production apparatus} with {TAIL ~ solution feed control} to eliminate build up of products on a solid reactant 
with
{ HEAD ~ Hydrogen production apparatus } with { TAIL ~ solution feed control } to eliminate build up of products on a solid reactant
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH