Boiling CHF phenomena in water and FC-72
2
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
Extensive researches toward pool boiling characteristics have been widely investigated. However,the correct understanding of its boiling crisis by Critical Heat Flux (CHF) phenomenon during steady andtransient heat transfer as a fundamental database for designing heat generation systems is still need to beclarified. The pool boiling CHFs were investigated to clarify the generalized phenomena of transition to filmboiling at transient condition. The CHFs were measured on 1.0 mm diameter horizontal cylinder of platinumfor exponential heat generation rates with various periods for saturated liquids at atmospheric pressure. The incipienceof boiling processes was completely different depending on pre-pressurization. Also, the dependenceof pre-pressure in transient CHFs changed due to the wettability of boiling liquids. The trend of typical CHFswere clearly divided into the first, second and third groups for long, short and intermediate periods,respectively. By the effect of pre-pressurization, the boiling incipience mechanism was replaced from that byactive cavities entraining vapor to that by the HSN in originally flooded cavies.
Abstract
Extensive researches toward pool boiling characteristics have been widely investigated. However,the correct understanding of its boiling crisis by Critical Heat Flux (CHF) phenomenon during steady andtransient heat transfer as a fundamental database for designing heat generation systems is still need to beclarified. The pool boiling CHFs were investigated to clarify the generalized phenomena of transition to filmboiling at transient condition. The CHFs were measured on 1.0 mm diameter horizontal cylinder of platinumfor exponential heat generation rates with various periods for saturated liquids at atmospheric pressure. The incipienceof boiling processes was completely different depending on pre-pressurization. Also, the dependenceof pre-pressure in transient CHFs changed due to the wettability of boiling liquids. The trend of typical CHFswere clearly divided into the first, second and third groups for long, short and intermediate periods,respectively. By the effect of pre-pressurization, the boiling incipience mechanism was replaced from that byactive cavities entraining vapor to that by the HSN in originally flooded cavies.
참고문헌 (9)
- A. Sakurai, "Mechanisms of subcooled pool boiling CHFs depending on sub-cooling, pressure, and test heater configurations and surface conditions in liquids", Proceedings of The American Society of Mechanical Engineers International Mechanical Engineering Congress & Exposition, pp.1~13 (2002)
- J. Park, "Steady-state and transient CHFs in various liquids due to ex-ponentially increasing heat inputs", Proceedings of The 3rd Asian (OCMT-QDU) Cooperative Technology and Education Conference, pp.5~10 (2008)
- B. P. Avksentyuk, "Characteristics of heat transfer crisis during boiling of alkali metals and organic fluids under free convection conditions at reduced pressure", Prog. Heat Mass Transfer, 7, pp.355~362 (1973)
- A. Sakurai, "New transition phenomena to film boiling due to in-creasing heat inputs on a solid surface in pres-surized liquids", Instability in Two Phase Flow Systems, HTD-260(H00838), pp.27~39 (1993)
- J. Y. Chang, "Film boiling incipience at the departure from natural convection on flat, smooth surfaces", Journal of The American Society of Mechanical Engineers, 120, pp.402~409 (1998)
- A. Sakurai, "Pool boiling critical heat flux on a horizontal cylinder in subcooled water for wide ranges of subcooling and pressure and its mechanism", Proceedings of the American Society of Mechanical Engineers Thirty-first National Heat Transfer Conference, HTD-326, pp.93~104 (1996)
- A. Sakurai, "Mechanisms of transitions to film boiling at CHFs in subcooled and pressurized liquids due to steady and increasing heat in-puts", Nuclear Engineering and Design, 197, pp.301~356 (2000)
- K. Fukuda, "Transient pool boiling heat transfer due to in-creasing heat inputs in subcooled water at high pressures", Proceedings of the 7th International Meeting on Nuclear Reactor Thermal Hydraulics, Saratoga Springs, 1, pp.554~573 (1995)
- Heat transfer in con-densation and boiling, "S. S. Kutateladze", USAEC, ~, pp.AEC-tr-3770 (1959)