Computational fluid dynamics investigation of a Stirling engine with one‐way oscillating flow cycle for efficient waste heat recovery

Abstract Facing the dual challenges of climate change and resource sustainability, efficient recovery of medium‐low temperature industrial waste heat is crucial for achieving the “dual carbon” goals. Stirling engines (SEs) have emerged as a preferred solution due to their unique advantages. However, traditional cycles suffer irreversible heat loss from non‐ideal isothermal heat transfer. The one‐way oscillatory flow cycle (OOFC) offers an innovative fix by using adiabatic processes, yet existing low‐order models fail to capture key 3D transient phenomena, causing large prediction deviations. Based on the GPU‐3 benchmark, this study develops the first full 3D computational fluid dynamics OOFC engine model (OEM) with real geometries. Comparative analysis with the SE model, OEM achieves the first full‐system 3D transient simulation of OOFC, which is not only capturing overlooked critical phenomena but also exhibits excellent performance: indicated power increases by 23.5% to 4993 W, thermal efficiency rises by 80% to 60%, and Relative Carnot efficiency jumps from 47% to 87%. Additionally, the OEM reduces the regenerator's peak temperature by 20%, facilitating structural simplification and cost reduction. This work provides a high precision numerical foundation for OOFC's engineering application, confirming its potential as an efficient, scalable waste heat recovery solution.