Investigation of heat transfer and pressure drop of CO2 two-phase flow in a horizontal minichannel |
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| Authors: | J Wu T Koettig Ch Franke D Helmer T Eisel F Haug J Bremer |
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| Affiliation: | 1. CERN, TE-CRG-CI, 1211 Geneva 23, Switzerland;2. University of Applied Science, Esslingen, Germany;1. Boiling and Two-Phase Flow Laboratory (BTPFL), School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907, USA;2. NASA Glenn Research Center, 21000 Brookpark Road, Cleveland, OH 44135, USA;1. Department of Mechanical, Mechatronics and Manufacturing Engineering (KSK-Campus), UET Lahore, Pakistan;2. Department of Energy Technology, Division of Applied Thermodynamics and Refrigeration, Royal Institute of Technology KTH, Sweden;1. Laboratory of Heat and Mass Transfer, LTCM, École Polytechnique Fédérale de Lausanne, Station 9, CH-1015 Lausanne, Switzerland;2. ABB Switzerland Ltd, Corporate Research, Segelhofstrasse 1K, CH-5405 Baden 5 Dättwil, Switzerland;1. Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;2. University of Chinese Academy of Sciences, Beijing 100039, China;1. Department of Mechanical Engineering, Korea University, Anam-Dong, Sungbuk-Ku, Seoul 136-713, Korea;2. Department of Mechanical Engineering, Hanbat National University, Duckmyung-Dong, San 16-1, Daejeon 305-719, Korea |
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| Abstract: | An innovative cooling system based on evaporative CO2 two-phase flow is under investigation for the tracker detectors upgrade at CERN (European Organization for Nuclear Research). The radiation hardness and the excellent thermodynamic properties emphasize carbon dioxide as a cooling agent in the foreseen minichannels. A circular stainless steel tube in horizontal orientation with an inner diameter of 1.42 mm and a length of 0.3 m has been used as a test section to perform the step-wise scanning of the vapor quality in the entire two-phase region. To characterize the heat transfer and the pressure drop depending on the vapor quality in the tube, measurements have been performed by varying the mass flux from 300 to 600 kg/m2 s, the heat flux from 7.5 to 29.8 kW/m2 and the saturation temperature from ?40 to 0 °C (reduced pressures from 0.136 to 0.472). Heat transfer coefficients between 4 kW/m2 K and 28 kW/m2 K and pressure gradients up to 75 kPa/m were registered. The measured data was analyzed corresponding to the dependencies on heat flux, mass flux and saturation temperature. A database has been established containing about 2000 measurement points. The experimental data was compared with common models recently developed by Cheng et al. 1], 2] to cross check their applicability. The overall trends and experimental data were reproduced as predicted by the models before the dryout onset, and deviations have been analyzed. A modified friction factor for the pressure drop model 1] in mist flow has been proposed based on the experimental data. |
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