R141b气液两相喷射器性能研究

Study of the Performance of a R141b Gas-liquid Two-phase Ejector

考虑实际流体性质、混合室阻力和喉部激波现象，采用等压混合模型，根据质量守恒、动量守恒和能量守恒建立中心进气两相喷射器一维模型。以R141b为工质，研究在不同入口参数和混合室截面积变化比（混合室喉部截面积与混合室入口截面积之比）下喷射器的升压特性以及入口参数和混合室截面积变化比对喷射器出口压力和喷射系数的影响。结果表明：在一定工况下，入口主蒸汽压力每增加0．5MPa，喷射器出口压力提高约0．002MPa；入口引射液体压力每增加0．1MPa，出口压力约升高0．6MPa。相对于入口主蒸汽参数的变化，入口引射液体参数变化对喷射器的升压特性影响更大。另外，随着混合室截面变化比的增大，升压效果下降。在入口引射液体参数为0．1MPa／299K和0．2MPa／321K的条件下，混合室截面积比分别增至0．6和0．4时，出口处蒸汽不能完全凝结。研究结果适用于大部分工质，为喷射器的设计和运行提供理论指导。

With the properties of the real fluid, the resistance of the mixture chamber and shock wave phenomenon occurred at the throat being taken into consideration and by employing a constant pressure mixture model, based on the mass, momentum and energy conservation laws, established was a one-dimensional model for two phase ejectors with the steam being centrally admitted. At various ratios between the sectional areas of the throat and the inlet of the mixture chamber,with R141b serving as the working medium, studied was the pressure rise characteristics of an ejector and the influence of the above-mentioned ratio on the pressure at the outlet of the ejector and the injection coefficient. The results show that under certain operating conditions, if the main steam pressure at the inlet increases by each 0.5 MPa, the pressure at the outlet of the ejector will increase by about 0. 002 MPa. If the liquid pressure at the inlet of the ejector increases by every 0. 1 MPa, the outlet pressure will increase by around 0.6 MPa. Relative to changes of the main steam parameters at the inlet, changes of the injection liquid parameters at the inlet will have a bigger influence on the pressure rise characteristics of the ejector. In addition ,with an increase of the above-mentioned ratio, the pressure rise effectiveness will get worsened. Under the condition of the injection liquid parameters at the inlet being 0.1 MPa/299 K and 0.2 MPa/321 K respectively,when the above-mentioned ratio increases to 0.6 and 0.4 respectively, the steam at the outlet will not be completely condensed. The foregoing research findings are applicable for a majority of working media and can offer theoretical guide for design and operation of various ejectors.