An assessment of optimal airside heat transfer per unit friction power characteristics of compact heat exchangers

This paper evaluates an optimal airside thermal-hydraulic performance of compact heat exchangers. Seventy-five airside surfaces have been chosen, i.e. standard reference of Kays and London, to represent louver-fin, strip-fin, wavy-fin, plain-fin, pin-fin, finned circular tubes and finned flat tubes. A robust evaluation method is implemented by an estimation of the heat transfer rate per unit pumping power with and without considering the heat exchanger compactness. Experimental data of Colburn j-factor and Fanning friction factor (f) are used to estimate both the heat transfer rates and the friction power, respectively. The results demonstrate that strip-fin surface 1/10-27.03 shows an optimal heat transfer values per unit friction power when the compactness is taken into consideration. Nonetheless, pin-fin surface PF-4(F) shows an optimal heat transfer rate per pumping power when neglecting the importance of the compactness. The geometries having an optimal thermal-hydraulic performance for each airside type (with or without considering the compactness) are recommended as benchmarks to assess the performance of similar airside surfaces.