Models for Prediction of Incipient Boiling Heat Flux and Wall Superheat

1 Models for Prediction of Incipient Boiling Heat Flux and Wall Superheat 

The first approach developed by Hsu (1962) is widely used to determine ONE in conventional size channels and in micro-channels (Sato and Matsumura 1964 Davis and Anderson 1966 Celata et al. 1997 Qu and Mudawar 2002 Ghiaasiaan and Chedester 2002 Li and Cheng 2004 Liu et al. 2005). These models consider the behavior of a single bubble by solving the one-dimensional heat conduction equation with constant wall temperature as a boundary condition. The temperature distribution inside the surrounding liquid is the same as in the undisturbed near-wall flow, and the temperature of the embryo tip corresponds to the saturation temperature in the bubble 7s,b- The vapor temperature in the bubble can be determined from the Young-Laplace equation and the Clausius-Clapeyron equation (assuming a spherical bubble)  

The temperature distribution in the undisturbed fluid over the heated surface is described by the equation 

From Eqs. (6.1) and (6.4) one can find the limiting values of the cavity radius of active sizes on the heated surface 

It should be stressed that such models are valid only when the medium is continuous. Measurements by Ye et al. (2004) showed that bubble nucleation in water may be considered as continuous when rc 10 nm. 

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