| Title |
Pool Boiling Heat Transfer Coefficient of R245fa on the Plain Tube and the Low Fin Tube |
| Authors |
박기정(Ki-Jung Park) ; 이요한(Yohan Lee) ; 임병덕(Byeongdeok Lim) ; 정동수(Dongsoo Jung) |
| Keywords |
풀 비등 열전달계수 ; 낮은 핀관 ; 냉매 245fa ; 증발기 ; 칠러 Pool boiling heat transfer coefficients ; Low fin tube ; R245fa ; Evaporator ; Chiller |
| Abstract |
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 kW/m2 to 10 kW/m2 with an interval of 10 kW/m2. Wall temperatures are measured directly by thermocouples inserted through holes of 0.5 mm 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. |