Experimental study on the liquid-side characteristics of meso-channel heat exchangers in fuel cell vehicles

A meso-channel parallel flow heat exchanger could be used as a radiator for fuel cell vehicles to dissipate waste heat from a fuel cell stack (FCS) to cooling air. Working fluid in tube-side channels was 50% glycol-water mixture. An experiment was conducted on an FCS radiator PFHX A with 2.685 mm hydraulic diameter meso-channels. The influences of condition parameters were analyzed. The critical Reynolds number from laminar to transitional flow in the meso-channels was defined at about 1800. Thus, correlations of heat transfer coefficient Nuf and friction factor ff were developed. Compared with some existing correlations, the new correlations correlated better with experimental values. The correlations well predicted Nuf and ff for another two radiator samples, PFHX B and PFHX C, with 2.268 mm and 2.295 mm diameter channels. It was suggested that the correlations could be useful for performance prediction and design optimization of meso-channel heat exchangers under extensive operating conditions.