بررسی تأثیر فشار ورودی ثانویه بر عملکرد یک اجکتور

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد، گروه مکانیک، واحد تهران شرق، دانشگاه آزاد اسلامی، تهران، ایران

2 استادیار، دانشکده انرژی‌های تجدیدپذیر، گروه مهندسی هوافضا، دانشگاه صنعتی ارومیه، ارومیه، ایران

3 استادیار، گروه مکانیک، واحد تهران شرق، دانشگاه آزاد اسلامی، تهران، ایران

چکیده

اجکتور مهمترین بخش چرخه تبرید اجکتوری است. در این مطالعه برای اولین بار بصورت عددی به مطالعه تأثیر فشار ورودی ثانویه بر جریان داخل اجکتور پرداخته شده است. تأثیر تغییر فشار ورودی ثانویه بر فشار، عدد ماخ و دمای سیال بررسی ‌شده است. معادلات حاکم بر جریان با روش حجم محدود و یک مدل تراکم‌پذیر لزج دو بعدی متقارن محوری و کاملاً آشفته حل شده است. با مقایسه نتایج عددی بدست آمده با نتایج حل تحلیلی و تجربی موجود تطابق قابل قبولی بین آنها وجود دارد. به منظور رسیدن به بهینه‌ترین عملکرد اجکتور، در چندین فشار ورودی ثانویه، بازده اگزرژی و نسبت مکش محاسبه و مقایسه شده تا بهینه‌ترین حالت عملکردی استخراج گردد. نتایج نشان داد که به ازای فشارهای ورودی کمتر از 8/0 بار، جریان برگشتی داخل اجکتور رخ می‌دهد ولی با افزایش فشار تا 5/1 بار، جریان بهبود یافته و بعد از آن حالت یکتواختی بوجود می‌آید. با کاهش فشار ورودی ثانویه از فشار بهینه 5/1 بار تا زمانیکه جریان برگشتی رخ می‌دهد، نسبت مکش حدود 105% و بازده اگزرژی حدود 64% کاهش می‌یابد.

کلیدواژه‌ها

موضوعات


[1] Rogdakis E. D., Alexis G. K., Investigation of ejector design at optimum operating condition, Energy Conversion and Management, Vol. 41, No. 17, pp. 1841-1849, 2000.
[2] Dahmani A., Aidoun Z., Galanis N., Optimum design of ejector refrigeration systems with environmentally benign fluids, International Journal of Thermal Sciences, Vol. 50, No. 8, pp. 1562-1572, 2011.
 
[3] AL-Khalidy N., Zayonia, A., Design and Experimental Investigation of an Ejector in an Air-Conditioning and Refrigeration System, ASHRAE Trans, Vol. 101, Part 2, pp. 383-391, 1995.
[4] Hjang B. J., Petrenko V. A., Samofatov I. Y., Shchetinina N. A., Collector Selection for Solar Ejector Cooling System, Solar Energy, Vol. 71, No. 4, pp. 269-274, 2001.
[5] Chen J., Havtun H., Palm B., Investigation of Ejectors in Refrigeration System: Optimum Performance Evaluation and Ejector Area Ratios Perspectives, Applied Thermal Engineering, Vol. 64, No. 1-2, pp. 182-191, 2014.
[6] Sun D. W., Variable geometry ejectors and their applications in ejector refrigeration systems, Energy, Vol. 21, No. 10, pp. 919-929, 1996.
[7] Smierciew K., Gagan J., Butrymowicz D., Application of numerical modelling for design and improvement of performance of gas ejector, Applied Thermal Engineering, Vol. 149, No. 25, pp. 85-93, 2019.
[8] Selvaraju A., Mani A., Analysis of an ejector with environment friendly refrigerants, Applied Thermal Engineering, Vol. 24, No. 5, pp. 827-838, 2004.
[9] Sun D. W., Eames I. W., Performance characteristics of HCFC-123 ejector refrigeration cycles, International Journal of Energy Research, Vol. 20, No. 10, pp. 871-885, 1996.
[10] Selvaraju A., Mani A., Analysis of a vapor ejector refrigeration system with environment friendly refrigerants, International Journal of Thermal Sciences, Vol. 43, No. 9, pp. 915-921, 2004.
[11] Sun D. W., Eames I. W., Recent Developments in the Design Theories and Applications of Ejector- A Review, Fuel and Energy Abstracts, Vol. 36, No. 5, 1995.
[12] Huang B. J., Chang J. M., Petrenko V. A., and Zhuk, K. B., A Solar Ejector Cooling System Using Refrigerant R141b, Solar Energy, Vol. 64, No. 4-6, pp. 223-226, 1998.
[13] Li X.  Wang T.  Day B., Numerical analysis of the performance of a thermal ejector in a steam evaporator, Applied Thermal Engineering, Vol. 30, No. 17-18, pp. 2708-2707, 2010.
[14] Yu J., Song X., Ma M., Theoretical Study on a Novel R32 Refrigeration Cycle with a Two-Stage Suction Ejector, International Journal of Refrigeration, Vol. 36, No. 1, 2013.
[15] Munday J. T. and Bagster D.F., A New Ejector Theory Applied to Steam Jet Refrigeration, Industrial & Engineering Chemistry Process Design and Development, Vol. 16, No. 4, pp. 442-449, 1977.
[16] Huang B. J., Chang J. M., Empirical correlation for ejector design, International journal of Refrigeration, Vol. 22, No. 5, pp. 379–388, 1999.
[17] Riffat S. B., Omer S. A., CFD modelling and experimental investigation of an ejector refrigeration system using methanol as the working fluid, International Journal of Energy Research, Vol. 25, No. 2, pp. 115-128, 2001.
[18] Desevaux P., Mellal A., Alves de Sousa Y., Visualization of secondary flow choking phenomena in a supersonic air ejector, Journal of Visualization, Vol. 7, No. 3, pp. 249-256, 2004.
[19] Sorouradin A., Mehr A. S., Mahmoudi S. M. S., Development of new model for prediction the performance of ejector refrigeration cycle, Modares Mechanical Engineering Journal, Vol. 12, No. 4, pp. 133-147, 2012. [In Persian]
[20] Patankar S. V. and Spalding D. B., A calculation procedure for heat, mass and momentum transfer in three-dimensional parabolic flows, International journal of heat and mass transfer, Vol. 15, No. 10, pp. 1787-1806, 1972
[21] Rhie C., Chow W. L., Numerical study of the turbulent flow past an airfoil with trailing edge separation, AIAA journal, Vol. 21, No. 11, pp. 1525-1532, 1983.
[22] Munday J. T., Bagster D. F., A new ejector theory to steam jet refrigeration, Journal of The American Chemical Society, Vol. 16, No. 4, pp. 442–449, 1977.
[23] Sun D. W., Eames I. W., Recent developments in the design theories and applications of ejectors—a review, journal of Energy institute, Vol. 68, No. 5, pp. 65–79, 1995.
[24] Huang, B. J., Chang, J. M., Empirical correlation for ejector design, International journal of Refrigeration, Vol. 22, No. 5, pp. 379–388, 1999.
[25] Wang X. D., Dong J. L., Numerical study on the performances of steam jet vacuum pump at different operating conditions, Journal of Vacuum, Vol. 84, No. 11, pp. 1341–1346, 2010.
[26] Pianthong K., Seehanam W., Behnia, M., Sriveerakul T., Aphornratana S., Investigation and improvement of ejector refrigeration system using computational fluid dynamics technique, Energy Conversion and Management, Vol. 48, No. 9, pp. 2556-2564, 2007.
[27] 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, International Journal of Thermal Sciences, Vol. 46, No. 8, pp. 823-833, 2007.
[28] Sriveerakul T., Aphormratana S., Chunnanond K., Performance prediction of steam ejector using computational fluid dynamics: part 1. Validation of the CFD results, International Journal of Thermal Sciences, Vol. 46, No. 8, pp. 812–822, 2007.
 [29] Han Y., Wang X., Sun H., Zhang G., Guo L., Tu J., CFD simulation on the boundary layer separation in the steam ejector and its influence on the pumping performance, Journal of Energy, Vol. 167, No. 15, pp. 469-483, 2019.
[30] Zhu Y., Cai W., Wen C., Li Y., Numerical investigation of geometry parameters for design of high performance ejectors, Applied Thermal Engineering, Vol. 29, No. 5, pp. 898–905, 2009
[31] Ji M., Utomo T., Woo J., Lee Y. H., Jeong H. M., Chung H., CFD investigation on the flow structure inside thermo vapor compressor, Energy, Vol. 35, No. 6, pp. 2694–2702, 2010.
[32] Ruangtrakoon N., Aphornratana S., Sriveerakul T., Experimental studies of a steam jet refrigeration cycle: effect of the primary nozzle geometries to system performance, Thermal Fluid Science journal, Vol.35, No. 4, pp. 676– 683, 2011.
[33] Negeed E. S. R., Enhancement of ejector performance for a desalination system, International Journal of Nuclear Desalination, Vol. 3, pp. 13, 2009.
[34] Power, R. B., steam Jet Ejectors for the Process Industries, New York: McGraw-Hill, 1994.
[35] Balamurugan S., Gaikar V. G., Patwardhan A. W., Effect of ejector configuration on hydrodynamic characteristics of gas–liquid ejectors, Chemical Engineering Science, Vol. 63, pp. 11, 2008.
[36] Zhu Y., Cai W., Wen C., Li Y., Numerical Investigation of Geometry Parameters for Design of High Performance Ejectors, Applied Thermal Engineering, Vol. 29, No. 5, 2008.
[37] Keenan H., Neumann E., Lustwerk F., An Investigation of Ejector Designs by Analysis and Experiment. Massachusetts Institute of Technology, Guided Missiles Program, 1948.
[38] Rogdakis E., Alexis A., Design and Parametric Investigation of an Ejector in an Air Conditioning System, Applied Thermal Engineering, Vol. 20. No. 2, 2000.
[39] Kairouani L., Elakhdar M., Nehdi E., Bouaziz N., Use of Ejectors in a Multievaporator Refrigeration System for Performance Enhancement, International Journal of Refrigeration, Vol. 32, No. 6, 2009.
[40] Selvaraju A., Mani A., Experimental Investigation on R134a Vapor Ejector Refrigeration System, International Journal of Refrigeration, Vol. 29, 2006.
[41] Kumar V., Singhal G., Subbarao P. M. V., Study of supersonic flow in a constant rate of momentum change (CRMC) ejector with frictional effects, Applied Thermal Engineering, Vol. 60, pp. 61-71, 2013.