This is totally unfamiliar - but unless someone with specific knowledge can step in, I'll give it a go.
flow rate in kW/h / specific heat x delta T makes sense - that would be the volume of water required to transfer that amount of heat energy per second.
However - I baulk at
'given the value v 0.59 m/s equals a transfer rate of 20kW x 0.59m/s' (I think you meant 200kW)
I'm not clear on what transfer rate means in this context - you have a power multiplied by a speed - that is energy-per-second multiplied by metres-per-second. That doesn't give a result that means anything to me physically. But if it were divided instead of multiplied, you would have energy-per-meter - that is the total energy in a length of pipe . That sounds like a useful thing to know? (roughly 339 kilowatt-seconds per meter)
Am I helping or hindering?