اندازه‌گیری ضریب انتقال حرارت جریان جوشش مادون‌سرد در فضای بین دو لوله دایروی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه تبدیل انرژی، دانشکده مهندسی مکانیک، دانشگاه صنعتی شاهرود، شاهرود، ایران

2 دانشیار دانشکده مهندسی مکانیک دانشگاه صنعتی شاهرود، شاهرود، ایران

3 Shahrood University of Tech, Shahrood, Iran

چکیده

در مطالعه حاضربا ساخت بستر آزمایشگاهی،به بررسی تجربی انتقال حرارتجریان جوشش مادون‌سرد در بین دو لوله هم‌محور عمودیبا قطر داخلی و خارجی بترتیب 50/7 و 70/6 میلی‌متر در فشار اتمسفریک و سیال کاری آب پرداخته شدهو اثر پارامترهایی مانند شار حرارتی، دبی جرمی، دمای مادون‌سرد ورودی و استفاده از اسفنج متخلخل فلزی برروی ضریب انتقال حرارت بررسی شده‌است. نتایج بدست‌آمده از این پژوهش که در محدوده دبی جرمی kg/s 0/012 تا kg/s 0/0286 می‌باشد، نشان می‌دهد که انتقال حرارت از دو مکانیسم جابجایی اجباری و جوشش جریانی تشکیل می‌یابد که اثر هر یک از پارامترهای فوق بر روی این دو مکانیسم انتقال حرارت مورد بررسی قرارگرفته‌است. ضریب انتقال حرارت به شدت تابعی از شار حرارتی اعمال شده می‌باشد. با زیادشدن شار حرارتی، ضریب انتقال حرارت افزایش یافته و با تغییر دبی جرمی در محدوده ذکرشده (در ناحیه جوشش مادون‌سرد)، تا 30% افزایش می‌یابد. همچنین، استفاده از محیط متخلخل اسفنج فلزی (با تخلخل 95 درصد)، ضریب انتقال حرارت جریان جوشش مادون‌سرد را تا 30 درصد افزایش می‌دهد. اعتبارسنجی نتایج تجربی بدست‌آمده نیز با گزارشات معتبر انجام شده‌است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Measurement of subcooled flow boiling heat transfer coefficient in vertical annulus tube

نویسندگان [English]

  • Masoud Yarahmadi 1
  • Mohammad Mohsen Shahmardan 2
  • Mohsen Nazari 3
  • Alireza Asgharzadeh 1
1 Fluid Mechanics Department, Shahrood University of Technology, Shahrood, Iran
2 Associated professor, Faculty of mechanical Engineering, Shahrood University of Technology, Shahrood, Iran
چکیده [English]

The boiling heat transfer, especially the subcooled flow boiling, is one of the cooling systems being used in industries due to their high heat transfer coefficient. The subcooled flow boiling happens when the bulk flow temperature and the interface temperature are lower and higher, respectively than the saturated temperature corresponding to the flow pressure. In the current study, an experimental apparatus was constructed, and subcooled flow boiling in an annulus tube was investigated. The annulus tube is in the vertical direction, and the internal and external diameters are 50.7 and 70.6 mm. The operating pressure was 1 atm, and the working fluid was water. In this investigation, heat flux, mass flow rate and the inlet subcooling effectiveness on heat transfer coefficient are considered. The experiments were performed in the mass flow rate range of 0.012 kg/s to 0.0286 kg/s in which the flow consists of both forced convection and flow boiling. The results show that the heat transfer coefficient is highly dependent on heat flux in a direct relationship. The mass flow reduction causes heat transfer coefficient increments to 30% in subcooled boiling regions. The use of porous media also increases the subcooled flow boiling heat transfer coefficient up to 30%. The validation of empirical results has also been done with valid previous reports.

کلیدواژه‌ها [English]

  • heat transfer
  • Subcooled Flow boiling
  • Experimental study
  • Vertical tube
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