Modeling and simulation of a helical-finned tube integrated with paraffin wax in a solar water heater system for enhanced thermal energy storage performance

Flat-plate solar water heaters are widely used due to their ease of use and acceptable performance relative to their cost.However, the novelty of this work lies in studying numerical simulations using computational fluid dynamics for the integration of helical half-fins into a phase-change material, placed on the back side of the absorber tube surface of a flat-plate solar water heater.The finite-volume method was used to analyze the phase-change material's transition time from liquid to molten state.Calculations for both (Ra ≈ 2.3 × 10³) and (Ste ≈ 0.19) revealed the true behavior of latent heat transfer during the phase-change material's melting.Numerical analysis showed a 9.33% increase in the average liquid content in the helical half-fin model from 2:00 PM to 8:00 PM, indicating that the paraffin melting rate is faster in this model compared to the paraffin-only model.In addition, the temperatures of the water exiting the three samples at midnight were 300.37 K, 302.043K, and 304.36 K, respectively.These results confirm that the improved thermal performance of the solar water heater is due to the integration of both paraffin wax and spiral fins, which that accelerates the melting process, and thus improves thermal energy storage