Development of a critical heat flux mapping method for fin-structured surfaces. Issue 9 (1st September 2016)

• Record Type: Journal Article
• Authors: Choi, Jin Young; NO, Hee Cheon
• Is Part Of: Journal of nuclear science and technology. Volume 53:Issue 9(2016)
• Page Start: 1321
• Page End: 1331
• Publication Date: 2016-09-01
• Subjects: severe accident -- passive safety -- critical heat flux -- fin structure -- liquid demand-side limit -- liquid supply-side limit -- hot spot model -- CHF map; Nuclear engineering -- Periodicals; Nuclear physics -- Periodicals; Nuclear energy -- Periodicals; 621.4805
• DOI: 10.1080/00223131.2015.1105165
• Languages: English
• ISSNs: 0022-3131

Abstract

ABSTRACT: In this study, we performed critical heat flux (CHF) experiments using structured surfaces to validate the parameter effects and understand their physical meanings. Experimental results showed that the CHF has a peak value as the fin geometry changes. Fins with height of 0.5 mm produced the largest CHF, 1.7 MW/m 2, and fins longer than 2 mm reduced the CHF values. To explain the results, a CHF mapping method was developed describing the liquid supply-side and demand-side limits. The liquid demand-side limit is governed by the heat removal capability, mainly the nucleate boiling, calculated using the hot spot model. We consider three liquid supply-side limits restricting the liquid supply to the heating surface: capillary limit and counter-current flow limitations (CCFLs). The capillary limit is determined by balancing the capillary pressure and viscous dissipation in the liquid film on the fin side. The CCFL in the structure is calculated using the Wallis correlation and the CCFL in the free volume limits the liquid downward flow by the vapor jetting from the heating surface. The CHF map for our experimental results successfully describes the CHF trend of the structured surfaces. As a result, we concluded that CHF mapping method is an effective means of explaining CHF in pool boiling.