مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

مطالعه تجربی تاثیر رطوبت نسبی در توزیع قطرات و انتقال حرارت گذرا و میانگین چگالش روی سطوح آبدوست و آبگریز

نوع مقاله : پژوهشی اصیل

نویسندگان
پریسا دهقانی
سید مصطفی حسین علی پور
حبیب‌الله اکبری
دانشگاه علم و صنعت
10.48311/MME.23.12.685
چکیده
به منظور بررسی تاثیر درصد رطوبت نسبی در انتقال حرارت و توزیع قطرات در پدیده چگالش روی سطوح آبدوست مس و آبگریز مس با پوشش تفلون، دستگاه تستی ساخته شده­است تا شرایط محیطی کنترل­شده­ای فراهم کند. در تمامی آزمایش­ها سرعت جریان هوای ورودی، دمای هوای ورودی، دمای هوای رسیده به سطح آزمایش، دمای آب، ارتفاع سطح آب، دمای سطح آزمایش در مقادیر مشخصی با استفاده از کنترل پی آی دی ثابت نگه داشته شدند و در هر آزمایش رطوبت نسبی در مقادیر 80، 88 و 96 درصد تعیین و کنترل شده­است. نتایج بررسی گذرای انتقال حرارت نشان می­دهد زمانی لازم است تا پدیده چگالش به وقوع بپیوندد که هرچه آبدوستی سطح و رطوبت نسبی بیشتر باشد این زمان کمتر خواهد بود، همچنین میانگین انتقال حرارت به مدت 60 دقیقه محاسبه شده و نشان داده است با افزایش رطوبت نسبی میانگین ضریب انتقال حرارت افزایش می­یابد و در شرایط محیطی یکسان ضریب انتقال حرارت روی سطوح آبدوست بیشتر از آبگریز است. در بررسی گرافیکی اندازه قطرات نیز مشاهده شده­است که بزرگترین قطرات روی سطوح آبدوست در رطوبت­های نسبی 88 و 96 درصد در محدوده قطر هیدرولیکی 35/0 تا 4/0 بوده و روی سطوح آبگریز در رطوبت­های نسبی 80 و 88 درصد بزرگترین قطرات در محدوده قطر هیدرولیکی 2/0 تا 25/0 میلیمتر بوده­است.
کلیدواژه‌ها
آبدوست
آبگریز
کنترل پی آی دی
درصد رطوبت نسبی
ضریب انتقال حرارت
توزیع قطرات

موضوعات

عنوان مقاله English

Experimental Study of the Effect of Relative Humidity on Droplet Distribution and Transient and Average Condensation Heat Transfer on Hydrophilic and Hydrophobic Surfaces

نویسندگان English

Parisa Dehghani
Seyed Mostafa Hosseinalipoor
Habibolah Akbari
University of Science and Technology
چکیده English

To investigate the effect of relative humidity percentage on heat transfer and distribution of droplets in the condensation phenomenon, a test device with the ability to provide and control different environmental conditions was made, and therefore, the hydrophilic (copper) and hydrophobic (Teflon coating on copper) surfaces were measured under controlled environmental conditions. In all the tests, the inlet air flow rate, inlet air temperature, air temperature reaching the test surface, water temperature, water surface height, and test surface temperature were kept constant at specific values using PID control. Each test's relative humidity values of 80, 88, and 96% have been determined and controlled. The results of the transient investigation of heat transfer show that it takes time for the condensation phenomenon to occur, and the higher the surface hydrophilicity and relative humidity, the shorter this time will be. Also, the average heat transfer for 60 minutes was calculated. It showed that the average heat transfer coefficient increases with increasing humidity. Under the same environmental conditions, the heat transfer coefficient on hydrophilic surfaces is higher than on hydrophobic ones. In the graphical analysis of the droplet size, it has been observed that the most oversized droplets on hydrophilic surfaces at relative humidities of 88 and 96% are in the hydraulic diameter range of 0.35 to 0.4, and on hydrophobic surfaces are at relative humidities of 80 and 88% in the hydraulic diameter range of 0.2 to 0.25 mm.

کلیدواژه‌ها English

hydrophilic
Hydrophobic
PID Control
relative humidity percentage
Heat Transfer Coefficient
droplet distribution
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مهندسی مکانیک مدرس
دوره 23، شماره 12
آذر 1402
صفحه 685-695