Accurate condensing steam flow modeling in the ejector of the solar-driven refrigeration system

摘要

The ejectors are widely employed in power engineering installations, both refrigeration, and thermal ones. In the paper, a steam ejector of a solar-driven refrigeration system is investigated numerically, using different CFD models, to reveal the flow structures and evaluate its performance. A modified nucleation model adopting the Benson and Shuttleworth surface tension definition is proposed. The model composed by the modified nucleation model and Young's droplet growth equation demonstrates the superiority in predicting the non-equilibrium condensation phenomenon. An ejector experimental data is contrasted with three different numerical models, the results show that the effect of the non-equilibrium condensation (NEC) on the steam ejector performance cannot be ignored, and the modified model can accurately predict the ejector performance. An investigation of a steam ejector being a crucial part of a solar-driven refrigeration system is carried out employing different models. The internal flow structures and ejector performance are investigated, the difference of results predicted by three numerical models are compared and analyzed. The results show that the non-equilibrium condensation process reduces the entrainment ratio in critical mode, but it will enlarge the critical mode zone. Besides, the treatment of steam property has a certain impact on the calculation results.