Transient investigation of mini-channel regenerative heat exchangers: Combined experimental and CFD approach

This paper presents a combined approach based on experiment and CFD as an alternative to single-blow method to investigate heat transfer and flow friction of three mini-channel regenerative heat exchangers (MCRHX), having channel hydraulic diameters of 1.5, 1 and 0.5 mm. Experiments were conducted to measure pressure drop and the transient thermal responses at the inlet and outlet of each MCRHX. The thermal response predicted from CFD, based on transient conjugated heat transfer simulations, was iteratively solved until it matched the experimental data within an acceptable deviation. The results showed that 0.5 mm MCRHX had the highest interstitial heat transfer coefficient due to the increased specific surface area. However, the penalty is the increased pressure drop. Moreover, Nusselt number and friction factor correlations were obtained for each configuration to correlate mini-channel heat transfer characteristics.