Some individuals insist, that because of the higher coolant velocity (if we use a higher volume pump), the heat transfer in the HE/radiator is lower, because "the heat does not have enough time to convect out of the coolant, due to flow being too fast".
IMO: a shear heresy.
The equations cited in this paper
show the only time dependent element,which is m
, (fluid mass flow rate, kg/s), is in the numerator, hence the heat flux q
(W/m^2) shall increase proportionally to the fluid mass flow rate, (eq. 6.21-6). In another words, larger the pump trough-put - the higher heat transfer and efficiency of the exchange.
The same is true for the heat transfer coefficient, h, in eq. 6.21-7.
Some individuals are probably thinking in terms of the coolant temperature change (delta t), which is different. Higher flow will certainly result in a lower coolant temperature change, but that is actually desirable, as it's associated with a lower thermal resistance of that heat exchanger. At a system level, that is what you want to achieve. The lower coolant temperature change is compensated by the higher coolant flow rate, and the reduction in the latter is greater than the decrease in the former.