Helical and chaotic heat exchangers: Flow regimes and efficiency

Helical coiled tubes are renowned for enhancing mixing and promoting heat transfer efficiency, making them highly valuable in various heat transfer applications. Nevertheless, the stabilizing effects of secondary flows in helical coils extends the laminar regime to higher Reynolds numbers than in straight pipes. This persistence of laminar flow state reduces longitudinal mixing and consequently limits the rates of convective heat transfer. This research introduces a novel chaotic heat exchanger designed to induce chaotic advection through an alternating Dean flow. To take advantage of a coiled system while improving its performance within the laminar regime of applications. The primary goal is to demonstrate the enhanced capabilities of our chaotic heat exchanger by comparing its performance against traditional helical coils. Utilizing Direct Numerical Simulation, our study explores the flow and heat transfer characteristics within both designs. Results reveal that the new configuration significantly improves hydro-thermal performance and demonstrates great potential across a Reynolds number range of 800–8600. Additionally, the study provides an in-depth analysis of the flow structures and examines the development of the thermal boundary layer, while highlighting the role of chaotic advection in enhancing mixing efficiency.