Thermodynamic approach for designing the two-phase motive nozzle of the ejector for transcritical CO2 heat pump system
Thermodynamic approach for designing the two-phase motive nozzle of the ejector for transcritical CO2 heat pump system
复制标题
DOI：
10.1016/j.egypro.2017.12.382
复制
发表时间：
2017-12
期刊：
影响因子：
--
通讯作者：
M. Al-Tameemi;Zhibin Yu
中科院分区：
文献类型：
--
作者：
M. Al-Tameemi;Zhibin Yu
本文采用一维热力学分析方法对跨临界CO2热泵系统中两相喷射器的主喷嘴进行了设计和性能评价。两种热力学方法（理想和非理想）的膨胀过程进行了比较。的操作参数和相关性是适应从验证的实验和理论研究公开文献。计算了穿过主喷嘴的工作流体（CO2）的质量流率、密度和质量。研究了CO2通过覆盖-扩张喷管的等熵膨胀过程。得到了制冷剂的马赫数、速度和声速等超声速特性，并分析了它们之间的关系。推导了与喷管几何域有关的其它设计参数，即面积、面积比和直径。结果表明，在喷管出口段，检测到两相流和正激波。在超声速流动特性方面，理想模型和非理想模型之间有相似的趋势。非理想模型的区域、边界条件和结果可以通过CFD软件在2D和/或3D模型中进一步验证。
In this paper, a one-dimensional thermodynamic analysis is developed to design and evaluate the performance of primary nozzles in two-phase ejector utilized in the transcritical CO2heat pump system. Two thermodynamic approaches (ideal and non-ideal) are adapted to model the expansion processes for comparison. The operating parameters and correlations were adapted from verified experimental and theoretical studies in open literatures. Mass flow rate, density and quality of the working fluid (CO2) across the primary nozzle are calculated. The isentropic expansion of CO2through the coverage-diverge (C-D) nozzle is then studied. The supersonic properties of the refrigerant such as Mach number, velocity and the speed of sound are obtained and the relations between them are analysed. Other design parameters related to the nozzle geometrical domain namely the area, the area ratio and the diameters are deduced. The results show that at the nozzle exit section, two phase flow and normal shock wave were detected. There is a similar trend between ideal and non-ideal models in terms of supersonic flow characteristics. The domain, boundary conditions and results of non-ideal model could be further verified by a CFD software in 2D and/or 3D models.