Experimental study of inverted annular film boiling in a vertical tube cooled by R-134a |
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Authors: | Meamer El Nakla DC Groeneveld SC Cheng |
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Institution: | 1. Mechanical Engineering Department, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia;2. Thermalhydraulics Branch, Atomic Energy of Canada Limited, Chalk River, Canada K0J 1J0;3. Department of Mechanical Engineering, University of Ottawa, Ottawa, Canada K1N 6N5 |
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Abstract: | An experimental investigation of inverted annular film boiling heat transfer has been performed for vertical up-flow in a round tube. The experiments used R-134a coolant and covered a pressure range of 640–2390 kPa (water equivalent range: 4000–14,000 kPa) and a mass flux range of 500–4000 kg m−2 s−1 (water equivalent range: 700–5700 kg m−2 s−1). The inlet qualities of the tests ranged from −0.75 to −0.03. The hot-patch technique was used to obtain the subcooled film boiling measurements. It was found that the heat transfer vs. quality curve can be divided into four different regions, each characterized by a different mechanisms and trends. These regions are dependent on pressure, mass flux and local quality. A detailed examination of the parametric trends of the heat transfer coefficient with respect to mass flux, inlet quality, heat flux and pressure was performed; reasonably good agreement between observed trends and those reported in the literature were noted. |
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Keywords: | Inverted annular film boiling Hot-patch techniques |
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