A Theoretical Analysis of Air Cooling System Using Thermal Ejector under Variable Generator Pressure
Due to energy and environment context, research is looking for the use of clean and energy efficient system in cooling industry. In this regard, the ejector represents one of the promising solutions. The thermal ejector is a passive component used for thermal compression in refrigeration and cooling systems, usually activated by heat either waste or solar. The present study introduces a theoretical analysis of the cooling system which uses a gas ejector thermal compression. A theoretical model is developed and applied for the design and simulation of the ejector, as well as the whole cooling system. Besides the conservation equations of mass, energy and momentum, the gas dynamic equations, state equations, isentropic relations as well as some appropriate assumptions are applied to simulate the flow and mixing in the ejector. This model coupled with the equations of the other components (condenser, evaporator, pump, and generator) is used to analyze profiles of pressure and velocity (Mach number), as well as evaluation of the cycle cooling capacity. A FORTRAN program is developed to carry out the investigation. Properties of refrigerant R134a are calculated using real gas equations. Among many parameters, it is thought that the generator pressure is the cornerstone in the cycle, and hence considered as the key parameter in this investigation. Results show that the generator pressure has a great effect on the ejector and on the whole cooling system. At high generator pressures, strong shock waves inside the ejector are created, which lead to significant condenser pressure at the ejector exit. Additionally, at higher generator pressures, the designed system can deliver cooling capacity for high condensing pressure (hot season).
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.3346744Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 315
 S. He, Y. Li, R.Z. Wang, Progress of mathematical modelling on ejectors, Renew. and Sust. Ener. Rev. 13 (2009) 1760–1780.
 L. Wang, J. Liu, Tao Zou, J. Du, F. Jia, Auto-tuning ejector for refrigeration system, Energy 15 (2018), 536-543.
 M. Ridha, M. Ouzzane, Z. Aidoun, Numerical evaluation of ejector-assisted mechanical compression systems for refrigeration applications, Inter. J. of Ref. 43 (2014), 36-49.
 A. Dahmani, Z. Aidoun, N. Galanis, Optimum design of ejector refrigeration systems with environmentally benign fluids, Inter. J. of Therm. Sci. 50 (2011) 1562-1572.
 M. Ouzzane, Z. Aidoun, Model development and numerical procedure for detailed ejector analysis and design, App. Therm. Eng. 23 (2003), 2337–2351.
 J. Munday, D. Bagster, A new theory applied to steam jet refrigeration, Indus. & Eng. Chem. Process Design and Development 16 (1977); pp. 442–449.
 J. Cardemil, S. Colle, A general model for evaluation of vapor ejectors performance for application in refrigeration, Energy Convers Manag 64(2012), 79-86.
 Y. Jia, C. Wenjian, Area ratio effects to the performance of air-cooled ejector refrigeration cycle with R134a refrigerant. Energy Convers Manag 53(2012), 240-246.
 S. Varga, P. Lebre, A. Oliveira, CFD study of a variable area ratio ejector using R600a and R152a refrigerants, Int. J. Refrig.36(2013), 36(1):157-165.
 Z. Chen, X. Jin, C. Dang, E. Hihara, Ejector performance analysis under overall operating conditions considering adjustable nozzle structure, Int. J. Refrigeration 84 (2017), 274-286.
 N. Sag, H. Ersoy, Experimental investigation on motive nozzle throat diameter for an ejector expansion refrigeration system. Energy Convers Manag 124 (2016), 1-12.
 C. Li, J. Yan, Y. Li, et al. Experimental study on a multi-evaporator refrigeration system with variable area ratio ejector. Appl. Therm. Eng. 102 (2016), 196-203.
 S. Aphornratana, I. Eames, A small capacity steam-ejector refrigerator: experimental investigation of a system using ejector with movable primary nozzle, Int. J. Refrigeration 20 (1997), 352-358.
 L. Fenglei, R. Li, X. Li, Q. Tian, Experimental investigation on a R134a ejector refrigeration system under overall modes. Appl. Therm. Eng. 137 (2018), 784-791.
 M. Huang, J. M. Chang, C. P. Wang, V. A. Petrenko, A 1-D analysis of ejector performance, Int. J. Refrigeration 22, (1999), 354-364.