Comprehensive numerical modeling analysis and experimental validation of a multi-turn pulsating heat pipe

The aim of this paper is to present the results of the experimentally validated numerical code designed for thermal-fluid computations in pulsating heat pipes using CFD techniques. The analysis was carried out using the OpenFOAM software, where an algorithm was developed to simulate multiphase flow with phase change and coupled heat transfer between the fluid and solid domains. The article meticulously delineates the steps involved in implementing and validating the model, commencing from basic comparative tests like the Stefan problem, progressing through Scriven’'s bubble growth, and culminating in an experiment with single- and multi-turn pulsating heat pipes. The algorithm has been refined by including a convergence criterion based on the Galusinski-Vigneaux number, which allows faster results and reduces the likelihood of numerical anomalies. Finally, an experiment was carried out to evaluate the thermal efficiency of a two-loop heat pipe on a specially designed experimental set-up constructed by the authors. In the experiment, ethanol was utilized as the working fluid, operating within a temperature range of 20 to 90 °C. The experiment was carried out with three distinct filling ratios: 50 %, 62.5 %, and 75 %. The validated parameters included pressure and temperature at the measurement points and the experimentally derived thermal efficiency results were compared with the numerical results. The model showed an error of 7.06 ± 3.73 %.