Thermal hydraulic analysis of a trapezoidal corrugated tube under nonuniform heat flux conditions

Enhancing heat transfer by using Corrugation on surface of heat transfer conduits has received attention in scientific community due to its importance in heat transfer equipment. The role of heating arrangements on the corrugation surface remains unclear. Therefore, in this study, convective heat transfer through a trapezoidal corrugated tube was numerically investigated under three non-uniform heat flux (NUHF) conditions. Constant Heat Flux (CHF), Ascending Heat Flux (AHF), Descending Heat Flux (DHF), and Oscillating Heat Flux (OHF), are applied as heating conditions. Additionally, four variations of AHF were introduced to demonstrate different increasing heating arrangements. This paper performed comprehensive analysis of these non-uniform heat flux conditions, including velocity profile, heat transfer, pressure loss, and Thermal Hydraulic Performance (THP). The results show that AHF provided the maximum Nusselt number enhancement compared to CHF, DHF, and OHF. At a constant Reynolds number, the AHF configuration achieved an average Nusselt number increase of approximately 3.26% over the baseline, while DHF and OHF resulted in average reductions of 3.24% and 1.65%, respectively. AHF also yielded the highest Thermo-Hydraulic Performance (THP) value of 1.04 at a Reynolds number of 600, whereas DHF produced the lowest THP value of 0.965 at Re = 500. Among the four AHF cases, case 4 (1800/200 W/m²) demonstrated the highest Nusselt number enhancement - approximately 16.4% at Re = 500 and 14.37% at Re = 800. Based on the findings, the study provides insights to enhance thermal and hydraulic performance of corrugated pipe for applying heat exchangers and thermal equipment.