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Heat transfer and size distribution of active nucleation sites in boiling propane outside a tube
Authors:Andrea Luke  Dieter Gorenflo
Affiliation:1. Department of Building Science, School of Architecture, Tsinghua University, Beijing 100084, China;2. Young Researchers and Elite Club, North Tehran Branch, Islamic Azad University, Tehran, Iran
Abstract:Size distributions of active nucleation sites in pool boiling of propane on the outside of single horizontal copper and steel tubes with different surface finishes (emery ground and fine sandblasted) have been calculated from heat transfer measurements over wide ranges of heat flux and pressure. The model assumptions of Schömann for the heat transfer near growing and departing bubbles, which were applied in the calculations, have been modified and the calculated results have been compared to experimental investigations by high-speed video techniques. New measurements of the departure diameter dA and frequency f of the bubbles at the same conditions as the heat transfer measurements show that dA and f are influenced by the azimuthal position of the active nucleation sites on the tube and that the calculated results react sensitively to the input data for dA and f . A modification of the model is proposed.
Keywords:pool boiling   nucleation sites   hydrocarbons   bubble formation
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