Effect of contact resistance on thermo-hydraulic performance for finned tube heat exchanger

This study numerically investigates the impact of thermal contact resistance (TCR) at the fin-tube interface on the thermo-hydraulic performance (TPF) of finned-tube heat exchangers (FTHE). Simulations were performed using ANSYS Fluent software at Reynolds numbers of Re = 1000, 2000, 4000, and 8000. The effects of various thermal conductivity (k = 0.5 – 16.27 W/mK) and interface thicknesses (t = 0.1 – 0.8 mm) of thermal pastes (TP) used to reduce thermal contact resistance on the TPF, average Nusselt number, and flow characteristics were examined in detail. The results indicated that the thermal conductivity coefficient (k) of the TP plays a more dominant role in TPF and heat transfer compared to the TP thickness (t). The TPF showed a strong sensitivity to thermal conductivity up to k = 10 W/mK, after which the enhancement in thermo-hydraulic performance became marginal. Based on a comprehensive evaluation of the results, it was concluded that the interface contact resistance becomes negligible when a TP with a thermal conductivity above 10 W/mK is employed.