Performance Evaluation and Statistical Optimization of a Double Pipe Heat Exchanger using Response Surface Methodology

Abstract

This study evaluates the thermal performance of an innovative double-pipe heat exchanger featuring helical fins and internal baffles. Experiments were conducted to compare counter-flow and parallel-flow configurations using water as the working fluid. Utilizing a Box-Behnken Design under Response Surface Methodology (RSM), the research analyzed the impact of three independent variables inlet hot fluid temperature (70 ℃ to 90 ℃ ), annulus flow rate (0.167 to 0.50 kg/s), and inner pipe flow rate (0.083 to 0.250 kg/s) on critical performance metrics. The results indicate that the counter-flow arrangement significantly outperforms the parallel-flow setup, demonstrating a 14.57% improvement in the overall heat transfer coefficient and a 17.15% increase in the heat transfer rate. Furthermore, the counter-flow configuration achieved 9.98% higher effectiveness and a 4.56% higher Nusselt number than its parallel counterpart. Statistical optimization identified the peak operational efficiency for the counter-flow process at approximately 74.65%. Numerical analysis confirmed that increasing hot fluid temperature and mass flow rates enhances turbulence, thereby reducing thermal resistance in the boundary layer and maximizing heat exchange.