Numerical and experimental investigation of a refrigerator condenser with three distinct helical coil geometries

Purpose This study aims to examine how various helical coil shapes affect heat transfer efficiency, with the goal of identifying the optimal coil design to enhance heat flux and thermal performance in cylindrical tanks, especially for household refrigerator condensers. Design/methodology/approach This study uses both experimental and numerical methods to assess how coil shape affects heat transfer. Numerical simulations were conducted using the commercial computational fluid dynamics software Fluent 16.2. Three helical coil designs standard helical coil, conical coil and variable-pitch coil were compared, with numerical results validated against experimental data for accuracy. While the experimental setup in this study focuses on a household refrigerator condenser immersed in a tank, the principles identified for enhancing heat transfer using variable-pitch helical coils can be extended to other thermal systems. For example, the variable-pitch coil configuration, with its improved heat transfer performance, is likely to be beneficial in applications such as water heating systems, industrial condensers and even HVAC systems, where enhanced thermal efficiency is desired. Findings This study shows that variable-pitch helical coils significantly enhance heat transfer compared to normal and conical coils. Specifically, the variable-pitch coil boosts heat transfer by up to 36.47% over the normal helical coil and 18.74% over the conical coil. The average Nusselt number for the variable-pitch coil is 2.18, reflecting a 36.25% and 18.47% increase over the normal and conical coils, respectively. The smaller pitch in the lower section of the variable-pitch coil improves thermal stratification, optimizing heat distribution in the tank. Overall, this study concludes that the variable-pitch coil delivers the best heat transfer performance, particularly in reducing temperature stratification and enhancing the system’s thermal efficiency. Originality/value This study provides new insights into helical coil geometry, highlighting the advantages of variable-pitch coils for enhanced thermal performance. It extends existing research by demonstrating that coils with a variable pitch, especially those with a smaller pitch in the lower section significantly outperform traditional fixed-pitch and conical coils. These findings offer valuable implications for designing more efficient helical condenser coils, such as those used in water heating systems, leading to systems with higher natural heat transfer coefficients. By comparing the unique contribution of variable-pitch coils to heat transfer with previous studies on conical or variable-diameter coils, the research underscores how this novel approach more effectively optimises thermal characteristics. This innovation not only provides theoretical benefits but also offers practical advantages for improving thermal systems in real-world applications.