两相流引射循环制冷系统性能的数值模拟

Numerical simulation on performance of refrigeration system with two-phase ejector

文中提出了两相流引射制冷循环系统稳定工作判据,并据此对传统两相流引射制冷循环系统进行了改进,增加了辅助蒸发器以使系统稳定工作。在此基础上,对以R134 a为制冷剂的汽液两相流引射制冷循环的系统性能进行了数值模拟,分析了不同工况、不同引射比对系统性能的影响。数值模拟结果表明:在给定冷凝压力和蒸发压力工况下,两相流引射制冷循环系统中存在一个临界引射比使系统能够稳定正常工作,当引射比低于临界引射比时,系统需要增加辅助蒸发器才可正常运行;与传统等焓节流制冷循环相比,两相流引射制冷循环系统系能可提高20%-40%;且在较高冷凝温度下,两相流引射制冷循环更具优势;同时在较低的蒸发温度下提高引射比,可使两相流引射循环系统性能得到更大的改善。

The stability criterion of the two-phase ejector refrigeration（TPER） cycle was proposed.On the basis of this criterion,the traditional TPER cycle was improved with adding an auxiliary evaporator.The performance simulation of the new TPER cycle with the refrigerant R134a was carried out,and the effects of the working conditions and the entrainment ratio on the system performance were analyzed.The numerical simulation results show that,at the conditions of fixed condensing and evaporating pressures,there is a critical entrainment ratio,under which the TPER system can operate steadily.When the entrainment ratio comes below the critical one,an auxiliary evaporator must be added to keep the system operating steadily.Compared to the conventional refrigeration cycle with an expansion valve under the same working conditions,the COP improvement of up to 20%-40% can be obtained approximately,especially at the condition of higher condensing temperature.By increasing the entrainment ratio at lower evaporating temperature,the COP of the TPER cycle can be better improved in particular.