单螺杆膨胀机内有机工质泄漏特性的数值研究

Numerical Study of Leakage Characteristics of Organic Fluids in Single Screw Expander

为了研究单螺杆膨胀机内泄漏特性,建立单螺杆膨胀机热力学工作过程的数学模型和油气混合的两相泄漏模型,分析间隙高度对各泄漏通道泄漏量的影响,并比较3种有机工质R123、R134a、R245fa在不同转速和进气压力下对单螺杆膨胀机容积效率和泄漏量的影响.结果表明,9条泄漏通道中,螺杆与壳体之间的泄漏量占主要部分,其次是星轮与螺槽之间的泄漏量,星轮与壳体之间的泄漏量较小.增加转速和进气压力均可增大单螺杆膨胀机的容积效率.在相同的工况条件下,以R123为工质的单螺杆膨胀机容积利用率最高,其次是R245fa,R134a最低.

In order to investigate the internal leakage characteristics of the expander, a mathematical model of the thermodynamic working process and a two-phase leakage model for gas-oil flow were established. The influence of clearance height on the leakage path of different leakage path was analyzed, and the influence of rotational speed and inlet pressure on the volumetric efficiency and leakage flow rate under three organic fluids （i. e. R123, R134 and R245fa） was compared. The results show that the leakage through the clearance gap between screw rotor and shell accounts for the most part, followed by the leakage through the clearance gap between screw groove and gate rotor, and the leakage through the clearance gap between gate rotor and shell is relatively small. The volumetric efficiency increases with the rotational speed and the inlet pressure. The volumetric efficiency of the single screw expander using the 11123 as the working fluid is the best under the same working conditions, followed by R245fa and R134a.