캐노피 위크 구조를 갖는 유동 채널의 임계 열유속 증진에 대한 연구

Abstract

FBCW is 3-D porous capillary wick structure which is consist of evaporator, post and canopy with perforation to separate liquid and vapor path by reducing hydraulic resistance. The liquid is supplied to surface by capillary pressure on evaporator and it pass through porous media and vapor is vented to perforations. Liquid can be supply until liquid chocking limit when pressure drop of FBCW is equal to capillary pressure on evaporator and it is called CV-limit CHF. Vapor is vented to perforation and it disturb the liquid track which supply the liquid to FBCW on canopy. When vapor from perforation and liquid track reach K-H instability the liquid track is unstable and it can’t be maintained and liquid can’t be supply to surface. It called HD-limit CHF. CHF of FBCW is triggered by low value between CV-limit CHF and HD-limit CHF. It is important to enhance CV-limit CHF and HD-limit CHF and predict them. CV-limit CHF is enhanced by controlling parameters of FBCW in reducing pressure drop of evaporator, post, perforation. HD-limit CHF is increased by increasing mass flux. FBCW is fabricated by micro size spherical copper particles. Flow boiling experiments was conducted in DI water, Tin=97oC, mass flux 250 and 350 kg/m2s. The highest CHF was 5077 kW/m2 and it was 163.8% enhancement compare with the plain surface[1924 kW/m2]. CV-limit CHF prediction was well predicted in below 9.1% compared with experimental data. HD-limit CHF model was proposed in below 2.07% compared with experimental data.