两级单螺杆膨胀机空气动力系统性能研究

Research of Air Powered Engine System Using Two-stage Single Screw Expander

为了克服单螺杆气动汽车发动机单级动力系统能量利用率低的缺陷,应用热力学理论对压缩空气两级动力系统性能进行研究,采用变尺度数学优化算法建立数学模型,对两级系统的级间分配进行优化,并通过编程计算,对其获得的级间膨胀比优化结果进行验证,分析系统总效率和加热温度等因素对系统动力性能参数——总输出功和气耗率的影响。理论研究结果表明,储气压力30MPa,储气容积300L的两级系统,当各级入口温度相同时,其最优膨胀比组合为10∶7,此外,9∶7和9∶8也可作为优化膨胀比;系统效率和加热温度越高,系统的总输出功也越大,气耗率与之相反。证明采用两级系统并结合级间加热方式时可以大大改善系统的性能。

A new compressed air engine system based on two-stage single screw expander is proposed to increase the energy utilization rate of compressed air.The distribution of expansion ratios between stages is optimized by building mathematical optimal arithmetic model with variable metric method and is checked by programming calculation.The influence of total efficiency and heating temperature on the power performance parameters including total output work and air consumption rate is analyzed.Research results indicate the best match of expansion ratio is ten to seven（nine to seven and nine to eight are also good） for the same inlet temperature system with air tank of 30 MPa pressure and 300 L volume.Results also show that heating up inlet air or increasing the system efficiency can improve the total output work and reduce the air consumption rate.It is concluded that the compressed air engine system combined two-stage single screw expander with heating is better than single-stage system.