Influence of Shock Wave Structure on the Ejector’s Operating Characteristics

doi:10.12068/j.issn.1005-3026.2024.09.012

Abstract

Abstract:

An ejector refrigeration recycle system can not only save energy and protect the environment but also realize recycling because it uses water as the working medium. The structure of the shock wave inside the ejector， i.e. ， the core component of the system， is discussed and divided in detail by numerical simulation. The determination basis of the pseudo?shock region， constant velocity region， oblique shock region and positive shock region is given for the first time. The influence of shock wave structure on the ejector’s operating characteristics is discussed. The results indicate that the position of positive shock wave is affected by the outlet back pressure. The pseudo?shock region is the direct factor that determines the ejector’s entrainment ratio. Shock train is important in reducing the flow velocity and restoring pressure in the ejector. The presence of a shock?mixing layer separates the working steam from the flow path of the ejecting steam. The working steam passes through the shock?mixing layer to carry and accelerate the flow of the ejecting steam. The area of the shock?mixing layer is affected by the ejector’s geometry and the working conditions of the working steam. Therefore， understanding and mastering the structure of shock waves is of reference value to understand the internal fluid flow law of the ejector， to improve the working efficiency of the ejector， and to further improve and optimize the ejector’s geometry.

Key words: ejector, shock wave, pseudo?shock, shock train, shock?mixing layer

CLC Number:

TP 181

Yu HAN, Xiao-dong WANG, Peng-fei LI, Guang-li ZHANG. Influence of Shock Wave Structure on the Ejector’s Operating Characteristics[J]. Journal of Northeastern University(Natural Science), 2024, 45(9): 1309-1316.

Figures/Tables 8

Fig.1 Structured grid of steam ejectors

Fig.2 Grid independence verification

Table 1 Physical properties of the steam

属性	数值
密度（ρ）	理想气体
动力黏度（μ）/（ $k g ? m$ ^-1）	$1.34 × 10 - 5$
热导率（λ）/（ $W ? m - 1 ? K$ ^-1）	$0.026 ? 1$
比定压热容（c_p ）/（ $J ? k g - 1 ? K$ ^-1）	$2 ? 014.00$

Table 1 Physical properties of the steam

属性	数值
密度（ρ）	理想气体
动力黏度（μ）/（ $k g ? m$ ^-1）	$1.34 × 10 - 5$
热导率（λ）/（ $W ? m - 1 ? K$ ^-1）	$0.026 ? 1$
比定压热容（c_p ）/（ $J ? k g - 1 ? K$ ^-1）	$2 ? 014.00$

Fig.3 Structure of shock wave in steam ejector

Fig.4 Flow diagram under working steam pressure

Fig.5 Temperature cloud diagram under back pressure

Fig.6 Distribution curve of Mach number at centerline

Fig.7 Location and range of the shock?mixing layer

References 32

1	Khayyam H， Kouzani A Z， Hu E J.Reducing energy consumption of vehicle air conditioning system by an energy management system［C］//IEEE Intelligent Vehicles Symposium. Xi’an，2009：752-757.
2	Sumeru K， Martin L， Ani F N，et al.Energy savings in air conditioning system using ejector：an overview［J］.Applied Mechanics and Materials，2014，493：93-98.
3	Wei K C， Dage G A.An intelligent automotive climate control system［C］//IEEE International Conference on Systems，Man and Cybernetics.Vancouver，BC，2002：2977-2982.
4	Wang L， Cai W J， Zhao H X，et al.Experimentation and cycle performance prediction of hybrid A/C system using automobile exhaust waste heat［J］.Applied Thermal Engineering，2016，94：314-323.
5	Suzuki M.Application of adsorption cooling systems to automobiles［J］.Heat Recovery Systems and CHP，1993，13（4）：335-340.
6	Edmunds J A， Wuebles D L S M.Energy and radiative precursor emissions［M］.Richland：Pacific Northwest National Laboratory，1987：14-16.
7	Wang L W， Wang R Z， Oliveira R G.A review on adsorption working pairs for refrigeration［J］.Renewable and Sustainable Energy Reviews，2009，13（3）：518-534.
8	Sarbu I.A review on substitution strategy of non‑ecological refrigerants from vapour compression‑based refrigeration，air‑conditioning and heat pump systems［J］.International Journal of Refrigeration，2014，46：123-141.
9	Han Y， Wang X D， Sun H，et al.CFD simulation on the boundary layer separation in the steam ejector and its influence on the pumping performance［J］.Energy，2019，167：469-483.
10	Li A， Yeoh G H， Yuen A C Y，et al.Numerical simulation of condensation effect on a steam ejector by wet steam model［C］//Thirteenth International Conference on Flow Dynamics. Sendai，2016：10-12.
11	Li A， Yuen A C Y， Chen T B Y，et al.Computational study of wet steam flow to optimize steam ejector efficiency for potential fire suppression application［J］.Applied Sciences，2019，9（7）：1486.
12	Bartosiewicz Y， Aidoun Z， Mercadier Y.Numerical assessment of ejector operation for refrigeration applications based on CFD［J］.Applied Thermal Engineering，2006，26（5/6）：604-612.
13	Wu H Q， Liu Z L， Han B，et al.Numerical investigation of the influences of mixing chamber geometries on steam ejector performance［J］.Desalination，2014，353：15-20.
14	Zhu Y H， Jiang P X.Experimental and numerical investigation of the effect of shock wave characteristics on the ejector performance［J］.International Journal of Refrigeration，2014，40：31-42.
15	Lee M S， Lee H， Hwang Y，et al.Optimization of two‑phase R600a ejector geometries using a non‑equilibrium CFD model［J］.Applied Thermal Engineering，2016，109：272-282.
16	Han Y， Wang X D， Li A，et al.Optimum efficiency of a steam ejector for fire suppression based on the variable mixing section diameter［J］.Entropy，2022，24：1625.
17	Haghparast P， Sorin M V， Nesreddine H.The impact of internal ejector working characteristics and geometry on the performance of a refrigeration cycle［J］.Energy，2018，162：728-743.
18	张家豪.小型蒸汽喷射实验系统的结构改进和性能提高［D］.沈阳：东北大学，2015.
	Zhang Jia‑hao.Structure improvement and performance improvement of small steam injection experimental system［D］.Shenyang：Northeastern University，2015.
19	Pianthong K， Seehanam W， Behnia M，et al.Investigation and improvement of ejector refrigeration system using computational fluid dynamics technique［J］.Energy Conversion and Management，2007，48（9）：2556-2564.
20	Besagni G， Mereu R， Inzoli F.CFD study of ejector flow behavior in a blast furnace gas galvanizing plant［J］.Journal of Thermal Science，2015，24（1）：58-66.
21	Besagni G， Mereu R， Chiesa P，et al.An integrated lumped parameter—CFD approach for off‑design ejector performance evaluation［J］.Energy Conversion and Management，2015，105：697-715.
22	Carrillo J A E， Francisco J D L， José M S L.Single‑phase ejector geometry optimisation by means of a multi‑objective evolutionary algorithm and a surrogate CFD model［J］.Energy，2018，164：46-64.
23	Li A， Yuen A C Y， Wang W，et al.Numerical investigation on the thermal management of lithium‑ion battery system and cooling effect optimization［J］.Applied Thermal Engineering，2022，215：118966.
24	Sriveerakul T， Aphornratana S， Chunnanond K.Performance prediction of steam ejector using computational fluid dynamics：part 2. flow structure of a steam ejector influenced by operating pressures and geometries［J］.International Journal of Thermal Sciences，2007，46（8）：823-833.
25	Zhu Y H， Jiang P X.Experimental and numerical investigation of the effect of shock wave characteristics on the ejector performance［J］.International Journal of Refrigeration，2014，40：31-42.
26	Berana M S， Nakagawa M， Harada A.Shock waves in supersonic two‑phase flow of CO₂ in converging‑diverging nozzles［J］.HVAC&R Research，2009，15（6）：1081-1098.
27	Wang X D， Dong J L， Zhang G L，et al.The primary pseudo‑shock pattern of steam ejector and its influence on pumping efficiency based on CFD approach［J］.Energy，2019，167：224-234.
28	Desevaux P， Prenel J P， Hostache G.An optical analysis of an induced flow ejector using light polarization properties［J］.Experiments in Fluids，1994，16（3）：165-170.
29	Desevaux P.A method for visualizing the mixing zone between two co‑axial flows in an ejector［J］.Optics and Lasers in Engineering，2001，35（5）：317-323.
30	Bouhanguel A， Desevaux P， Gavignet E.Flow visualization in supersonic ejectors using laser tomography techniques［J］.International Journal of Refrigeration，2011，34（7）：1633-1640.
31	Wang H， Cai W J， Wang Y Y.Modeling of a hybrid ejector air conditioning system using artificial neural networks［J］.Energy Conversion and Management，2016，127：11-24.
32	Li H， Wang X D， Huang H L，et al.Numerical study on the effect of superheat on the steam ejector internal flow and entropy generation for MED-TVC desalination system［J］.Desalination，2022，537：115874.

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[4]	XIE Yuan-hua， MEI Jian， WANG Jie， ZHU Tong. Experimental Study on Disintegration of Excess Sludge by Explosive Shock Wave [J]. Journal of Northeastern University Natural Science, 2018, 39(3): 446-450.
[5]	WANG Xiao-dong， FU Qiang， YI Shu， LI He. Experimental Investigation of Operating Characteristics of Ejector in Steam Jet Refrigeration System [J]. Journal of Northeastern University Natural Science, 2017, 38(12): 1744-1747.
[6]	MA Juanli， SUN Wan， LIU Changhai， HOU Yu. Numerical Simulation of Decompression Expansion of Subcritical CO2 Through ConvergingDiverging Nozzle [J]. Journal of Northeastern University, 2013, 34(8): 1175-1178.