CO_2滑片膨胀机热力过程的试验研究  

Experimental Research on Internal Working Process of Rotary Vane Expander in CO_2 Refrigeration System

作　　者：杨炳春[1] 郭蓓[1] 彭学院[1] 邢子文[1] 

机构地区：[1]西安交通大学能源与动力工程学院,西安710049

出　　处：《西安交通大学学报》2008年第3期313-317,共5页Journal of Xi'an Jiaotong University

基　　金：教育部新世纪人才支持计划资助项目(NCET-06-0836)

摘　　要：为了提高制冷系统的效率,研制了滑片膨胀机,以替代跨临界CO2制冷循环中的节流阀.利用膨胀机气缸上2只相隔一定角度的压力传感器,获得了工作腔内压力随转角变化的完整曲线(p-θ图),并通过p-θ图分析了膨胀机的内部热力过程.研究结果表明:所研制的滑片膨胀机能够实现连续、稳定的膨胀过程,但严重的内部泄漏使得膨胀过程中的压力下降非常迅速,并导致过度膨胀现象发生;通过在滑片底部设置弹簧,改善滑片与气缸内壁之间的密封,在p-θ图上能观察到膨胀过程趋于理想的情况;在膨胀机的进、出口之间密封圆弧处增加密封条,可以显著提高膨胀机的进、出口压力差,说明该处泄漏得到大幅减少;所研制的膨胀机绝热效率在20%左右,且随转速的改变没有明显的变化,降低高压差下的气体泄漏是今后样机改进的重点.A rotary vane expander was developed to replace the throttling valve to improve the coefficient of performance of the transcritical CO2 refrigeration cycle. A diagram of pressure variation with rotation angle （p-θ diagram） was recorded with two pressure sensors arranged in the expansion chamber in different angle positions. The internal thermodynamic process was analysed by means of the p-θ diagrams. The experimental results show that the rotary vane expander can work continuously and steadily while the serious internal leakage results in more rapid decrease in pressure during expansion than expected, leading to an unfavorable over-expansion. Arranging springs beneath the vanes can improve the expansion process by keeping a tight contact between the vane and the cylinder wall. A seal arranged between the inlet and outlet ports can increase the pressure difference through the expander by reducing the leakage directly from the high-pressure suction chamber to the low-pressure discharge chamber. The adiabatic efficiency is estimated to be about 20 percent and changes little with the rotation speed .

关 键 词：滑片膨胀机 跨临界CO2制冷循环 泄漏 

分 类 号：TB653[一般工业技术—制冷工程]