Improving the Thermal Performance of a Heat Exchanger using a New Passive Technology

Abstract

In this study, the oscillation technique was applied in a multi-tube heat exchanger with baffles. The Nusselt number was investigated in the heat exchanger (HE) over a wide range of operating conditions, Reynolds number (Re =205-3200), and oscillatory flow Reynolds number (Reo =0-3800). The results showed a significant enhancement in the tube-side Nusselt number, Nu. 5-fold heat transfer enhancement was achieved at maximum oscillatory and flow rates, the maximum Nu=180 at Re =1500 and Reo=3800. The flow rate had more impact on the heat transfer enhancement than the oscillatory flow by 1.25 when Re>1000. The thermal performance of the heat exchanger, TH, was also evaluated. TH decreased with the increasing flow rate and oscillatory flow due to the increase in the ΔP due to the increase in the mixing intensity. A high value of the thermal performance, TH=4.5, was achieved at Re=205, Reo=1500. According to the literature, this TH value indicated a significant improvement in heat transfer enhancement.