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열전달 촉진관에서 임계열유속까지의 풀 비등 열전달 계수
임병덕(Lim Byeongdeok),이요한(Yohan Lee),정동수(Dongsoo Jung) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.11
In this work, nucleate pool boiling heat transfer coefficients(HTCs) of pure water on horizontal 26 fpi low fin, Turbo-B and Thermoexcel-E square surface of 9.53 mm length. Tested enhanced tubes HTCs are taken from 10 ㎾/㎡ to critical heat flux. Critical heat fluxes(CHFs) of all enhanced surfaces were greatly improved as compared to that of a plain surface in tested water. CHF of water on the 26fpi low fin surface, Thermoexcel-E surface, and Turbo-B was increased up to 320%, 275%, and 150% as compared to that of the plain surface. CHF of the Turbo-B enhanced surface were lower than that of the 26fpi low fin surface. The heat transfer enhancement ratios of the low fin surface and Turbo-B enhanced surface were 1.01~4.60, 0.84~4.22 respectively in the range of heat fluxes tested.
평활관과 낮은 핀관에서 R245fa의 풀 비등 열전달계수
박기정(Ki-Jung Park),이요한(Yohan Lee),임병덕(Byeongdeok Lim),정동수(Dongsoo Jung) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.3
In this work, pool boiling heat transfer coefficients(HTCs) of R22, R123, R134a, and R245fa are measured on both horizontal plain and 26 fpi low fin tubes. The pool boiling temperature is maintained at 7℃ and heat flux is varied from 80 ㎾/㎡ to 10 ㎾/㎡ with an interval of 10 ㎾/㎡. Wall temperatures are measured directly by thermocouples inserted through holes of 0.5 ㎜ diameter. Test results show that HTCs of high vapor pressure refrigerants are usually higher than those of low pressure fluids in both plain and low fin tubes. On a plain tube, HTCs of R245fa are 23.3% higher than those of R123 while on a 26 fpi low fin tube, HTCs of R245fa are 46.3% higher than those of R123. The fin effect is more prominent with low vapor pressure refrigerants than with high vapor pressure ones due to a sweeping effect.