Nonlinear Aspects of High Heat Flux Nucleate Boiling Heat Transfer

Abstract

This paper deals with potential nonlinear effects in nucleate boiling systems as a result of the behavior of individual nucleation sites on the heater surface. This requires detailed microscopic modeling of the surface. A computational model has been formulated for this purpose. The model addresses the three-dimensional transient conduction heat transfer process within the problem domain comprised of the macrolayer and heater. Hydrodynamic effects are represented through boundary conditions. Individual nucleation sites are activated or deactivated depending on the thermal conditions that prevail at the site. The model has been used to examine the behavior of sites on a realistic heater surface. The results indicate that significant spatial and temporal temperature variations can occur on the surface, and that thermal interactions among sites can result in some sites operating intermittently. Surface-averaged temperatures show nonlinear period-doubling behavior. A chaotic case was found. Qualitative comparisons are made to both local instantaneous temperature measurements and recent experiments that showed chaotic behavior. We believe that such nonlinear behavior is one of the reasons that mechanistic predictive capabilities for the boiling process have remained elusive.

Measurement of the fractal order of wall void fraction during nucleate boiling

“…Past research efforts have primarily explored boiling chaos by investigating thermal features using time-delay techniques (Shoji et al, 1995;Shoji, 2004;Zhang and Shoji, 2003a,b;Kuzma-Kichta et al, 2000;Fong et al, 1998Fong et al, , 2001Fong et al, , 2003Acharya et al, 2003;Sadasivan et al, 1994Sadasivan et al, , 1995a. In this study we explore boiling chaos by investigating hydrodynamic features (voids or bubbles) and evaluate chaos quantifiers (e.g., correlation dimension) using box-counting technique.…”

“…Both these groups and others (e.g., Acharya et al, 2003;Sadasivan et al, 1994Sadasivan et al, , 1995a focused their efforts on quantifying chaos in nucleate boiling. Shoji et al (1995) extended their analyses for quantifying boiling chaos (e.g., Lyapunov exponent, fractal order, attractors, etc.)…”

Heat Flux Controlled Pool Boiling of Zirconia–Water and Silver–Water Nanofluids on a Flat Plate: A Coupled Map Lattice Simulation

“…Since boiling is a kind of spatiotemporal chaotic phenomenon [13][14][15][16][17] CML has been applied in the past to simulate boiling processes.…”

A theoretical analysis of bubble interaction in boiling systems

“…The development of modern measurement techniques has provided much visualization of boiling processes and then synergetic effects [11][12][13]. Kenning and Yan [11] noted that active sites can co-exist within one bubble radius of each other and that the sites interact through the variation in wall temperature induced by embryo bubble generation, which results in intermittent bubbles generation.…”