An investigation on convective boiling heat transfer of R۱۲۳۴yf inside alternating flattened tubes
Publish place: The 31st annual conference between Iran Mechanical Engineering and the 9th Iran Power Plant Industry Conference
Publish Year: 1402
نوع سند: مقاله کنفرانسی
زبان: English
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شناسه ملی سند علمی:
ISME31_174
تاریخ نمایه سازی: 10 خرداد 1402
Abstract:
Alternating flattened tubes, which are made of plain and flattened sections at each segment, improve two-phase heat transfer by increasing the heat transfer surface, creating vorticities, and mixing the flow. The present study investigates the effect of vapor quality and mass velocity on the heat transfer coefficient in alternating flattened tubes. The test section consists of three different alternating tubes with an effective length of ۷۰ cm and an internal diameter of ۸.۲ mm. The flattening ratio, the number of segments, and segment length are the geometrical parameters that differ in test tubes. In this research, R۱۲۳۴yf refrigerant has been used, which is one of the new refrigerants with a global warming potential of ۴ and is a very suitable alternative to refrigerants such as R۱۲۳۴yf. A number of ۱۵۰ distinct experiments were performed in the range of vapor qualities of ۰.۰۹ to ۰.۹۱ and mass velocities of ۱۱۰, ۲۱۰, and ۳۰۰ kg/m۲s. The results show that the mass velocity and vapor quality always directly impact the heat transfer coefficient. It is also observed that the use of alternating flattened tubes increases the heat transfer coefficient by up to ۲۵۴% compared with simple round tubes.
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Authors
Amirhossein Haghighat
M.Sc. graduate; School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
MohammadAli Akhavan-Behabadi
Professor;School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Behrang Sajadi
Associate ProfessorSchool of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Rasool Mohammadi
Ph.D. Candidate;School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran