Exploring effective thermal energy exchange potential of delta-nabla-trapezoidal channels in heat exchangers

The performance and thermal efficiency of a heat exchanger are critical in various industrial applications, necessitating the continuous improvement of the thermal management system. In the present study, a novel heat exchanger which comprises of delta-nabla-trapezoidal (DNT) configurations of flow channels, is investigated and compared with commercially available concentric tube heat exchangers (CTHEs), to address the limitations of conventional design in terms of thermal efficiency and pressure drop. The current study is the first of its kind to explore the thermal energy exchange potential of the delta-nabla-trapezoidal heat exchangers (DNTHEs) with numerical simulations and experimentally validated them using an in-house designed experimental setup. The proposed heat exchanger comprises of triangular and trapezoidal cross-section channels that are arranged such that the hot fluid flows through the delta and nabla channels while cold fluid flows through the trapezoidal channels. The energy exchange between the two fluid streams is experimentally measured, and Nusselt number correlations are developed for various inlet mass flow rates. The numerical simulations are then used to predict local fluid and heat flow patterns with velocity and temperature profiles. Experimental results indicate a reasonable energy balance, revealing a maximum loss of 15% across all sets of experiments. Furthermore, the cold-side temperature increased to its maximum of 22 K, while the hot-side temperature decreased by 25 K across all tested conditions. The simulation results demonstrated an enhanced energy balance, characterized by a maximum loss of 10%. The thermal efficiency of the proposed DNTHE was experimentally assessed and compared to that of a CTHE in parallel and counter flow configurations. Under similar operating conditions, the maximum heat flux in DNTHE and CTHE was 18.35 and 14.26 kW/m², respectively. Furthermore, the largest difference in temperature drops and gains between DNTHE and CTHE are 15 and 9 K, respectively. These findings confirmed the efficient thermal energy exchange potential of DNTHE in comparison to CTHE, establishing a new industrial standard for heat exchangers.