Nucleate pool-boiling heat transfer - II. Assessment of prediction methods

Part I of this paper has identified all significant boiling surface parameters affecting nucleate pool-boiling heat transfer and has investigated their parametric trends, thus providing a measure of the state of the art in this area. This part of the paper examines the existing prediction methods for the heat transfer coefficient (HTC) under this boiling regime. Six heat transfer pool-boiling correlations that are well known in the literature have been selected and their prediction accuracy has been assessed against available and well-documented experimental databases. These databases provide HTCs obtained: (i) under pool-boiling conditions of fluids such as water, ethanol, R-113, and n-heptane; and (ii) on the following large-size horizontal surfaces: thick plates (made of copper, aluminum, brass, and stainless steel), and a horizontal circular disk (plated with a thin layer of polished chromium). For completeness, the microgeometry characteristics of several boiling surfaces are included here, even though they are not fully utilized in the present analysis. The surface microgeometry has been characterized by 14 roughness parameters measured with a laser profilometer. The analysis concludes that within the investigated ranges of boiling conditions, working fluids and boiling surfaces, the Rohsenow and Pioro nucleate pool-boiling correlations are the most accurate among those assessed. The Rohsenow and Pioro correlations use constants and powers for non-dimensional numbers that correspond to a specific surface-fluid combination, as opposed to the other correlations that use fixed values regardless of the surface-fluid combination. (author)