Thermal Performance, Exergy, and NTU Analysis of a Shell and Helical Coil Heat Exchanger using non-Newtonian Nanofluids

Abstract

An experimental investigation was conducted to evaluate the thermal and thermodynamic performance of a shell-and-helical-coil heat exchanger (SHHE) using nanofluids. Al2O3, CuO, and Fe2O3 nanoparticles dispersed in a 0.5 wt.% CMC base fluid was employed as the shell-side working fluid. The shell-side nanofluid temperature was varied (40–60°C), and stirring speeds (500–1500 rpm) were adjusted to ensure proper dispersion, while water at 27°C was circulated through the helical coil at different flow rates corresponding to various Dean numbers. The system performance was analysed using the Number of Transfer Units (NTU) method and exergy analysis to assess heat transfer enhancement and thermodynamic irreversibility. The results indicate that NTU increases with increasing nanoparticle concentration and shell-side temperature due to enhanced thermal conductivity and improved convective heat transfer. However, because of increased entropy formation, energy loss rises as the Dean number (De) and temperature differential increase. While both parameters rose concurrently with increasing nanofluid concentration and temperature, an inverse relationship between NTU and exergy loss was found with flow rate. CuO demonstrated the best thermal performance among the nanofluids tested, followed by Al2O3 and Fe2O3. According to the study, nanofluids greatly improve heat transfer performance; however, in order to minimize energy destruction and ensure thermodynamically efficient operation, optimization is necessary.