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Abstract
Critical heat flux was measured for saturated pool boiling of 2-propanol/water mixture (9.4wt%) on a 12mm diameter horizontal disk at pressures of 5kPa to 100kPa. The CHF of the mixture was 1.5 to 2.2 times greater than that of water over the whole range of pressures. To examine the mechanism of the CHF improvement in the mixture, liquid-vapor behaviors close to the heating surface were measured using a conductance probe under atmospheric pressure. It was found that for boiling of the mixture, radial distributions of the void fraction and contact frequencies of the probe tip with vapor have a distinct peak near the periphery of the heating surface. This means that vapor generation is suppressed at a central area and enhanced near the periphery of the heating surface. The thickness of liquid layer beneath the vapor mass determined for the mixture at a center of the heating surface becomes considerably thicker than that of water. The formation of this thicker liquid layer is likely to be one cause of the CHF improvement in the 2-propanol/water mixture under atmospheric pressure.
Journal
- Transactions of the Japan Society of Mechanical Engineers. B [List of Volumes]
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Transactions of the Japan Society of Mechanical Engineers. B 75(752), 787-795, 2009-04-25 [Table of Contents]
The Japan Society of Mechanical Engineers