变工况双级压缩中间压力及其对系统性能的影响

基于质量与能量守恒方程，以转子压缩机几何模型为基础，建立反映中间压力形成过程的变容量双级压缩系统压缩机动态耦合模型，并利用实验对模型进行了校核。基于模拟和实验结果，分析了中间压力随时间的变化及其变工况特性。结果表明，中间压力具有脉动特性，但脉动幅值相对于时均值较小；在影响中间压力的因素中，低高压压缩机理论输气量比的影响最为显著，冷凝温度的影响明显小于蒸发温度的影响；系统制热量随中间压力的升高近似呈线性增加，而系统制热COP随中间压力升高具有先升高后降低的趋势，且存在最优值。

Intermediate pressure and its effect on performance of two-stage compression system with variable operating mode

A dynamic coupled model of a two-stage compression system with variable capacity reflecting the generation of intermediate pressure is constructed based on the rotary compressor geometry,the mass and energy conservation equations.The model is verified by the experiment.According to the results of simulation and experiment,the variation of the intermediate pressure with time and characteristics of variable operating modes were analyzed.The results show that the intermediate pressure has pulse characteristics,but the pulse amplitude is relatively small by comparison to the time-averaged value.Among the factors affecting the intermediate pressure,the ratio of theoretical displacement of the low compressor to that of the high one is the most significant one and condensation temperature is less significant than evaporation temperature.The heating capacity increases linearly with the intermediate pressure,while the change of the system COP for heating increases with intermediate pressure first and then decreases,and there exists an optimal value.