| Title |
Pool Boiling Heat Transfer Coefficients Up to Critical Heat flux on Thermoexcel-E Enhanced Surface |
| Authors |
이요한(Yohan Lee) ; 강동규(Dong-Gyu Kang) ; 장철한(Cheol Han Jang) ; 정동수(Dongsoo Jung) |
| DOI |
http://dx.doi.org/10.6110/KJACR.2012.24.9.685 |
| Keywords |
핵 비등 ; 열전달계수 ; 임계 열유속 ; Thermoexcel-E 촉진 표면 Nucleate pool boiling ; Heat transfer coefficients ; Critical heat flux ; Thermoexcel-E enhanced surface |
| Abstract |
In this work, nucleate pool boiling heat transfer coefficients(HTCs) of 5 refrigerants of different vapor pressure are measured on horizontal Thermoexcel-E square surface of 9.53 mm length. Tested refrigerants are R32, R22, R134a, R152a and R245fa. HTCs are taken from 10 kW/m2 to critical heat fluxes for all refrigerant at 7℃. Wall and fluid temperatures are measured directly by thermocouples located underneath the test surface and in the liquid pool. Test results show that critical heat fluxes(CHFs) of Thermoexcel-E enhanced surface are greatly improved as compared to that of a plain surface in all tested refrigerants. CHFs of all refrigerants on the Thermoexcel-E surface are increased up to 100% as compared to that of the plain surface. The improvement of Thermoexcel-E surface in CHF, however, is lower than that of the low fin surface. HTCs on Thermoexcel-E surface increase with heat flux. But after certain heat flux, HTCs began to decrease due to the difficulty in bubble removal caused by the inherent complex nature of this surface. Therefore, at heat fluxes close to the critical one, sudden decrease in HTCs needs to be considered in thermal design with Thermoexcel-E surface. |