پیوندهای مفید
آمار
| تعداد نشریات | 7 |
| تعداد شماره‌ها | 405 |
| تعداد مقالات | 5,424 |
| تعداد مشاهده مقاله | 5,542,899 |
| تعداد دریافت فایل اصل مقاله | 5,027,047 |
تاثیر اختلاف دما در انتقال حرارت و توزیع قطرات چگالش روی سطوح آبدوست و آبگریز | ||
| نشریه مهندسی مکانیک امیرکبیر | ||
| دوره 56، شماره 6، شهریور 1403، صفحه 811-832 اصل مقاله (2.38 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22060/mej.2024.22979.7703 | ||
| نویسندگان | ||
| پریسا دهقانی؛ سید مصطفی حسینعلی پور* ؛ حبیب الله اکبری | ||
| دانشکده مکانیک، دانشگاه علم و صنعت، تهران، ایران | ||
| چکیده | ||
| در این پژوهش تاثیر اختلاف دمای بین سطح و هوای مرطوب بر انتقال حرارت و توزیع قطرات بررسی شده است. بنابراین دستگاه تستی ساخته شده تا شرایط محیطی را کنترل کرده و با قرار گرفتن دو نوع سطح آبدوست و آبگریز در معرض هوای مرطوب پدیده چگالش رخ داده‌است. درصد رطوبت نسبی و سرعت جریان هوای مرطوب در تمامی آزمایش‌ها به ترتیب در مقادیر 88 درصد و 5 متر بر ثانیه ثابت نگاه داشته شده و اختلاف دمای لحاظ شده 4، 7 و 10 درجه سانتی‌گراد بوده‌است. میزان انتقال حرارت متغیر با زمان در طول 60 دقیقه انجام آزمایش نشان‌داده که برای شروع فرآیند چگالش زمانی لازم است که هرچه اختلاف دما و میزان انرژی سطح بیشتر باشد، این زمان کوتاه‌تر و میانگین انتقال حرارت نیز بیشتر می‌شود. عکس‌برداری از آزمایش‌ها نیز نشان داده که با افزایش اختلاف دما و انرژی سطح، زمان لازم برای افتادن اولین قطره کوتاه‌تر و قطر هیدرولیکی قطره خارج شده نیز بزرگتر است. نحوه توزیع قطرات در دقیقه 20 ام پس از شروع هر آزمایش نشان می‌دهد، با افزایش اختلاف دما تعداد قطرات بزرگتر به دلیل افزایش نرخ چگالش بیشتر بوده و نیز تعداد کوچکترین قطرات روی سطح آبگریز بیشتر از آبدوست است. | ||
| کلیدواژه‌ها | ||
| چگالش؛ انرژی سطح؛ اختلاف دما؛ انتقال حرارت؛ توزیع قطرات | ||
| عنوان مقاله [English] | ||
| Effect of temperature difference on condensation heat transfer and droplet distribution on hydrophilic and hydrophobic surfaces | ||
| نویسندگان [English] | ||
| Parisa Dehghani؛ Seyed Mostafa Hosseinalipour؛ Habibollah Akbari | ||
| School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran | ||
| چکیده [English] | ||
| The research examined the influence of temperature difference between surfaces and humid air on heat transfer and droplet distribution. A testing apparatus controlled environmental conditions and facilitated condensation on hydrophilic and hydrophobic surfaces. The relative humidity and speed of humid airflow were kept constant at 88% and 5 m/s, respectively, and the temperature difference considered was 4, 7, and 10 degrees Celsius. The varying heat transfer overtime during the 60 minutes has shown that it takes time to start the condensation process; the more the temperature difference and the amount of surface energy, the shorter this time is and the higher the average heat transfer is. The photography of the experiments has also shown that with the increase in temperature difference and surface energy, the time required for the first drop to fall is shorter, and the hydraulic diameter of the dropped drop is bigger. The distribution of the droplets in the 20th minute after the start of each experiment, in which no droplets have left the test surfaces yet, shows that with the increase in the temperature difference, the number of larger droplets is more due to the increase in the condensation rate. The number of the smallest droplets is higher on hydrophobic surfaces than on hydrophilic ones. | ||
| کلیدواژه‌ها [English] | ||
| Condensation, Surface Energy, Temperature Difference, Heat Transfer, Droplet Distribution | ||
| مراجع | ||
|
[1] D. Tanner, C. Potter, D. Pope, D. West, Heat transfer in dropwise condensation—Part I The effects of heat flux, steam velocity and non-condensable gas concentration, International Journal of Heat and Mass Transfer, 8(3) (1965) 419-426. [2] I. Tanasawa, J.-i. Ochiai, Expeimental study on dropwise condensatioin, Bulletin of JSME, 16(98) (1973) 1184-1197. [3] J. Su, Z. Sun, G. Fan, M. Ding, Experimental study of the effect of non-condensable gases on steam condensation over a vertical tube external surface, Nuclear Engineering and Design, 262 (2013) 201-208. [4] A. Fouda, M. Wasel, A. Hamed, E.-S.B. Zeidan, H. Elattar, Investigation of the condensation process of moist air around horizontal pipe, International Journal of Thermal Sciences, 90 (2015) 38-52. [5] Q. Yi, M. Tian, W. Yan, X. Qu, X. Chen, Visualization study of the influence of non-condensable gas on steam condensation heat transfer, Applied Thermal Engineering, 106 (2016) 13-21. [6] J. Lu, H. Cao, J. Li, Condensation heat and mass transfer of steam with non-condensable gases outside a horizontal tube under free convection, International Journal of Heat and Mass Transfer, 139 (2019) 564-576. [7] Y.-h. Gu, Q. Liao, M. Cheng, Y.-d. Ding, X. Zhu, Condensation heat transfer characteristics of moist air outside a three-dimensional finned tube, International Journal of Heat and Mass Transfer, 158 (2020) 119983. [8] X. Ma, J. Ma, H. Tong, H. Jia, The Investigation on Heat Transfer Characteristics of Steam Condensation in Presence of Noncondensable Gas under Natural Convection, Science and Technology of Nuclear Installations, 2021 (2021) 1-13. [9] X. Ma, X. Xiao, H. Jia, J. Li, Y. Ji, Z. Lian, Y. Guo, Experimental research on steam condensation in presence of non-condensable gas under high pressure, Annals of Nuclear Energy, 158 (2021) 108282. [10] M.S. Bonab, R. Kempers, A. Amirfazli, Determining transient heat transfer coefficient for dropwise condensation in the presence of an air flow, International Journal of Heat and Mass Transfer, 173 (2021) 121278. [11] C. Graham, P. Griffith, Drop size distributions and heat transfer in dropwise condensation, International Journal of Heat and Mass Transfer, 16(2) (1973) 337-346. [12] J.E. Castillo, J.A. Weibel, S.V. Garimella, The effect of relative humidity on dropwise condensation dynamics, International Journal of Heat and Mass Transfer, 80 (2015) 759-766. [13] H. Hu, G. Tang, D. Niu, Experimental investigation of convective condensation heat transfer on tube bundles with different surface wettability at large amount of noncondensable gas, Applied Thermal Engineering, 100 (2016) 699-707. [14] X. Chen, M.M. Derby, Combined visualization and heat transfer measurements for steam flow condensation in hydrophilic and hydrophobic mini-gaps, Journal of Heat Transfer, 138(9) (2016) 091503. [15] S.B. Barati, N. Pionnier, J.-C. Pinoli, S. Valette, Y. Gavet, Investigation spatial distribution of droplets and the percentage of surface coverage during dropwise condensation, International Journal of Thermal Sciences, 124 (2018) 356-365. [16] Y. Shi, G. Tang, L. Shen, Study of coalescence-induced droplet jumping during phase-change process in the presence of noncondensable gas, International Journal of Heat and Mass Transfer, 152 (2020) 119506. [17] D.-Y. Ji, J.-W. Lee, D. Kim, W. Hwang, K.-Y. Lee, Effective reduction of non-condensable gas effects on condensation heat transfer: Surface modification and steam jet injection, Applied Thermal Engineering, 174 (2020) 115264. [18] M. Muneeshwaran, C.-C. Wang, Energy-saving of air-cooling heat exchangers operating under wet conditions with the help of superhydrophobic coating, Energy Conversion and Management, 229 (2021) 113740. [19] X. Wang, W. Xu, Z. Chen, B. Xu, Dropwise condensation heat transfer on nanostructured superhydrophobic surfaces with different inclinations and surface subcoolings, International Journal of Heat and Mass Transfer, 181 (2021) 121898. [20] X.-H. Ma, X.-D. Zhou, Z. Lan, L. Yi-Ming, Y. Zhang, Condensation heat transfer enhancement in the presence of non-condensable gas using the interfacial effect of dropwise condensation, International Journal of Heat and Mass Transfer, 51(7-8) (2008) 1728-1737. [21] H. Hu, G. Tang, D. Niu, Experimental investigation of condensation heat transfer on hybrid wettability finned tube with large amount of noncondensable gas, International Journal of Heat and Mass Transfer, 85 (2015) 513-523. [22] X. Chen, J.A. Morrow, M.M. Derby, Mini-channel flow condensation enhancement through hydrophobicity in the presence of noncondensable gas, International Journal of Heat and Mass Transfer, 115 (2017) 11-18. [23] R. Gupta, C. Das, A. Datta, R. Ganguly, Background Oriented Schlieren (BOS) imaging of condensation from humid air on wettability-engineered surfaces, Experimental Thermal and Fluid Science, 109 (2019) 109859. [24] R. Wen, X. Zhou, B. Peng, Z. Lan, R. Yang, X. Ma, Falling-droplet-enhanced filmwise condensation in the presence of non-condensable gas, International Journal of Heat and Mass Transfer, 140 (2019) 173-186. [25] T.-Y. Zhang, L.-W. Mou, J.-Y. Zhang, L.-W. Fan, J.-Q. Li, A visualized study of enhanced steam condensation heat transfer on a honeycomb-like microporous superhydrophobic surface in the presence of a non-condensable gas, International Journal of Heat and Mass Transfer, 150 (2020) 119352. [26] K. Zhang, J. Hu, Z. Nan, Z. Chen, N. Wang, Experimental study of heat transfer characteristics on condensation in the presence of NCG through thermal resistance analysis, Progress in Nuclear Energy, (2020) 103591. [27] Y.-L. Wu, J.-W. Zheng, M. Muneeshwaran, K.-S. Yang, C.-C. Wang, Moist air condensation heat transfer enhancement via superhydrophobicity, International Journal of Heat and Mass Transfer, 182 (2022) 121973. | ||
|
آمار تعداد مشاهده مقاله: 178 تعداد دریافت فایل اصل مقاله: 199 |
||