External exchanges around a Chaotic Helix Exchanger in a thermal energy storage tank

This study compares the external heat transfer performances and energy efficiency of two heat exchanger geometries, Chaotic Helix Exchanger (CHE) and Helical Heat Exchanger (HHE), under varying flow rates, immersed in a thermal energy storage tank. External heat transfer performance refers to the ability of the heat exchanger to transfer heat between its surface and the surrounding fluid, which is crucial for optimizing energy efficiency in storage systems. The novelty of this work lies in the integration of chaotic advection-based heat exchangers into thermal storage systems, a topic that remains unexplored in the literature. Experimental methods involved dimensionless temperature ($\theta$) analyses and measurements of the external heat transfer coefficient ($h$). Results indicated that CHE maintained a consistent and predictable heat transfer process, with $\theta$ decreasing uniformly to equilibrium across all flow rates, while HHE showed sensitivity to flow rates, with initial fluctuations in $\theta$ before stabilization. The external heat transfer coefficients were similar for both geometries at most flow rates but differed slightly at intermediate rates. Additionally, temperature ratio analysis revealed that CHE consistently maintained a uniform temperature distribution (ratio = 0.99), while HHE exhibited initial peaks and non-uniformities before stabilizing. These findings show that CHE is more efficient in maintaining uniform heat transfer and minimizing energy losses, making it the better choice for energy-efficient heat exchanger design. The enhanced thermal stability and performance of CHE directly contribute to reducing energy consumption, especially in systems requiring consistent thermal regulation.