Numerical Simulation Analysis of Heat Transfer Enhancement With Multitype Twisted Strips Inserted

This paper uses numerical simulations to study the effects of six twisted‐strip inserts (multipassage, perforated (PF), center‐cleared (CC), single‐passage), their twist direction and pitch on the heat transfer, and flow resistance of twisted elliptical tubes. Multipassage strips (5‐passage most effective) boost heat transfer‐Nusselt number up 1.19–1.7 times versus tubes without inserts‐but sharply increase flow resistance (friction factor up 3.01–3.29 times). PF and CC strips balance heat transfer improvement with controlled resistance growth, with the latter showing optimal comprehensive performance in high‐Reynolds‐number regions (excellent overall performance factor values). Counter‐inserted strips outperform normally‐inserted ones in heat transfer but raise resistance more, with higher Nusselt numbers and friction factors at the same Reynolds number; counter‐inserted CC strips perform best (Nusselt number up 1.14–1.23 times, friction factor up 2.49–2.86 times). For single‐passage and CC strips, smaller twist pitch enhances Nusselt number and friction factor more regardless of insertion direction, and the normally‐inserted CC strip with 150 mm pitch achieves the best comprehensive performance factor.