Tseng, Meng-FanMeng-FanTsengMEI-JIAU HUANG2025-09-222025-09-222025-11-15https://www.scopus.com/record/display.uri?eid=2-s2.0-105014737534&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/732234Tubular heat exchangers are extensively used in industrial applications that require efficient thermal management. However, full-scale computational fluid dynamics (CFD) simulation of these systems demands large amounts of computing resources due to the presence of numerous thin-walled tubes. In this study, a hybrid simulation method is proposed to integrate the lumped-parameter thermal network (LPTN) model with CFD to reduce computational costs while maintaining high accuracy. It takes into account multi-dimensional heat conduction within the tube walls, the significance of which was recognized through a preliminary investigation, and incorporates empirical local Nusselt number correlations to capture tube-side convective heat transfer. The hybrid simulation method is first validated against a cross-flow heat exchanger with 16 tubes, demonstrating a 1.4 times speedup in computational time and a maximum outer wall temperature error of 0.19 K (1.23 %). To further test its scalability, the simulation of a cross-flow heat exchanger with 2125 tubes is conducted, achieving a 2.8 times acceleration. Different Nusselt number correlations were attempted, and the corresponding overall heat exchange rate calculated through the hybrid simulation is less than 1 % different from that of the full simulation. These results confirm the proposed hybrid simulation method as a computationally efficient alternative to full-scale CFD simulation, while ensuring reliable thermal performance predictions for large-scale tubular heat exchangers.Computational fluid dynamicsHybrid simulation methodLumped-parameter thermal network (LPTN)Tubular heat exchanger[SDGs]SDG7journal article10.1016/j.applthermaleng.2025.128024