محاسبه قطر بهینه ذرات جاذب سیلیکاژل در چیلرهای جذب سطحی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 کارشناسی ارشد، دانشکده مهندسی - مکانیک، دانشگاه فردوسی مشهد

2 استاد، دانشکده مهندسی مکانیک ، دانشگاه فردوسی مشهد

چکیده

یکی از روش‌هایی که امروزه برای تولید برودت در صنعت و تهویه مطبوع مورد استفاده قرار می‌گیرد؛ چیلرهای جذب سطحی‌اند که دارای مزایای زیادی نسبت به روش‌های مشابه هستند. با توجه به اهمیت بستر‌های جاذب در عملکرد چیلرهای جذب سطحی، در این مقاله به مدل‌سازی بستر ماده جاذب با مبدل حرارتی صفحه‌ای پرداخته شده که بین فین‌ها با ذرات سیلیکاژل SWS-1L پر شده است. برای مدل‌سازی بستر ماده جاذب معادلات پیوستگی، مومنتوم و انتقال حرارت سه بعدی در دستگاه مختصات عمومی حل شده است. برای حل همزمان معادلات وابسته به زمان در چهار حوزه سیال ناقل حرارت، لوله فلزی، فین‌ها و بستر ماده جاذب از روش حجم کنترل استفاده شده است. با استفاده از نتایج بدست آمده دیده شد که مقدار ضریب عملکرد با تغییر در قطر ذرات جاذب تغییر ناچیزی دارد اما مقدار ظرفیت سرمایش مخصوص دارای یک مقدار بهینه در قطر ذرات جاذب 37/0 میلیمتر است.

کلیدواژه‌ها


عنوان مقاله [English]

The Optimum Diameter of Silica- Gel Particles in Adsorption Chillers

نویسندگان [English]

  • mehdi Mahdavikhah 1
  • hamid Niazmand 2
چکیده [English]

Adsorption chillers are considered for the industrial and air conditioning applications due to their advantages over the conventional refrigeration systems. The performance of an adsorption chiller is mainly influenced by the adsorbent bed, therefore, this paper investigates a tube heat exchanger with plate fins as the adsorbent bed and silica gel(SWS-1L)-water as working pairs. In order to model the adsorbent bed, the continuity, momentum and energy equations are solved in a body fitted coordinate system and both the inter particle and intra particle mass transfer resistances are considered. The control volume method is used to solve the time dependent equations in four basic domains of thermal fluid, metal tube, fins and adsorbent bed, simultaneously. Flow patterns and pressure distributions though out the bed are examined in detail for all cycle. The results indicate that the particles diameter has a negligible effect on the coefficient of performance, while the specific cooling power and the cycle time  have an optimum value for particles diameter of 0.37mm.

کلیدواژه‌ها [English]

  • Adsorption Chiller
  • optimization
  • Numerical modeling
  • Silica Gel
[1] Aristov Y, “New family of solid sorbents for adsorptive cooling: Material scientist approach”, Journal of Engineering Thermophysics, No. 16, pp. 63- 72, 2007.
[2] Yong L., Sumathy K, “Comparison between heat transfer and heat mass transfer models for transportation process in an adsorbent bed”, International Journal of Heat and Mass Transfer, No. 47, pp. 1587- 1598, 2004.
[3] Riffel D., Wittstadt U., Schmidt F., Belo F.,Leite A., Ziegler F, “Transient modeling of an adsorber using finned-tube heat exchanger”, International Journal of Heat and Mass Transfer, No. 53, pp. 1473-1482,2010.
[4] Chua H., Ng K., Wang W., Yap C., Wang X,“Transient modeling of a two-bed silica gelwater
adsorption chiller”, International Journal of Heat and Mass Transfer, No. 47, pp. 659- 669, 2004.
[5] Miyazaki T., Akisawa A., Saha B., El-Sharkawy I., Chakraborty A, “A new cycle time allocation for enhancing the performance of two-bed adsorption chillers”, International Journal of Refrigeration, No.
32, pp. 846- 853, 2009.
[6] Kubota M., Ueda T., Fujisawa R., Kobayashi J., Watanabe F., Kobayashi N., Hasatani M, “Cooling output performance of a prototype adsorption heat pump with fin-type silica gel tube module”, Applied Thermal Engineering, No. 28, pp. 87- 93, 2008.
[7] Miyazaki T., Akisawa A, “The influence of heat exchanger parameters on the optimum
cycle time of adsorption chillers”, Applied Thermal Engineering, No. 29, pp. 2708-2717, 2009.
[8] Khan M., Alam K., Saha B., Hamamoto Y.,Akisawa A., Kashiwagi T, “Parametric study
of a two-stage adsorption chiller using reheat-The effect of overall thermal conductance and adsorbent mass on system performance”, International Journal of Thermal Sciences, No. 45, pp. 511- 519,2006.
[9] Di J., Wu J., Xia Z., Wang R, “Theoretical and experimental study on characteristics of a novel silica gel-water chiller under the conditions of variable heat source temperature”, International Journal of
Refrigeration, No. 30, pp. 515- 526, 2007.
[10] Freni A., Bonaccorsi L., Proverbio E.,Maggio G., Restuccia G, “Zeolite synthesised on copper foam for adsorption chillers: A mathematical model”,Microporous and Mesoporous Materials, No.120, pp. 402- 409, 2009.
[11] Wu W., Zhang H., Sun D, “Mathematical simulation and experimental study of a modified zeolite 13X-water adsorption refrigeration module”, Applied Thermal Engineering, No. 29, pp. 645- 651, 2009.
[12] Zhang L, “A three-dimensional nonequilibrium model for an intermittent adsorption cooling system”, Solar energy, No. 69, pp. 27- 35, 2000.
[13] Chang W., Wang C., Shieh C, “Design and performance of a solar-powered heating and cooling system using silica gel/water adsorption chiller”, Applied Thermal Engineering, No. 29, pp. 2100- 2105, 2009.
[14] Yang G., Xia Z., Wang R., Keletigui D.,Wang D., Dong Z., Yang X, “Research on a compact adsorption room air conditioner”,Energy Conversion and Management, No.47, pp. 2167- 2177, 2006.
[15] Poyelle F., Guilleminot J., Meunier F,“Experimental tests and predictive model of an adsorptive air conditioning unit”, Ind Eng Chem Res, No. 38, pp. 298- 309, 1999.
[16] Saha B., Chakraborty A., Koyama S.,Aristov Y., “A new generation cooling device employing CaCl2-in-silica gel-water system”, International Journal of Heat and Mass Transfer, No. 52, pp. 516- 524, 2009.
[17] Demir H., Mobedi M., Ülkü S, “Effects of porosity on heat and mass transfer in a granular adsorbent bed”, International Communications in Heat and Mass Transfer, No. 36, pp. 372- 377, 2009.
[18] Do D; Adsorption analysis: equilibria and kinetics, Volume 2, Imperial College Press London, 1998.
[19] Sodre J.R., Parise J.A.R., “Fluid flow pressure drop through an annular bed of spheres with wall effects”, Experimental Thermal and Fluid Science, No. 17, pp. 265-
[20] 275, 1998.
Klerk A., “Voidage Variation in Packed Beds at Small Column to Particle Diameter Ratio”, AIChE Journal, No. 49, pp. 2022-2029, 2003.
[21] Restuccia G., Freni A., Vasta S., Aristov Y, “Selective water sorbent for solid sorption chiller, experimental results and modelling”, International Journal of Refrigeration, No. 27, pp. 284- 293, 2004.