Comparative analysis of the natural convection process between hollow concrete brick layer and crushed rock layer |
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| Affiliation: | 1. State Key Laboratory of Frozen Soil Engineering, CAREERI, CAS, Lanzhou 730000, China;2. Sichuan Communication Surveying & Design Institute, Chengdu 610017, China;1. Vasyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine;2. B.I. Stepanov Institute of Physics NAS of Belarus, Minsk, Belarus;1. Department of Applied Chemistry, Harbin Institute of Technology, 92 Xidazhi Street, Harbin 150001, China;2. College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410012, China;3. GCL Solar Energy Inc, Xuzhou, Jiangsu, China;1. Materials Center Leoben Forschung GmbH, Roseggerstrasse 12, 8700 Leoben, Austria;2. Institute for Electron Microscopy and Fine Structure Research, Steyrergasse 17/III, 8010 Graz, Austria;3. ams AG, Tobelbaderstrasse 30, 8141 Premstätten, Austria;1. Busan Techno-Park, Center for Integrated Logistics Management, Busan, Republic of Korea;2. Department of Architecture, Pusan National University, Busandaehak-ro 63 beon-gil, Geumjeong-gu 609-735, Busan, Republic of Korea;1. Departamento de Física, Universidade Federal de Minas Gerais, 30123-970 Belo Horizonte, Minas Gerais, Brasil;2. I3N Departamento de Física, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal;3. Departamento de Física, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida, 431, 4200-072 Porto, Portugal;4. Facultad de Física – ICTM, Universidad de La Habana, Colina Universitaria, C.P. 10400 Habana, Cuba |
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| Abstract: | On the basis of cooling mechanisms and its factors of crushed rock layer widely used in the Qinghai–Tibet railway, a new hollow concrete brick layer is proposed for the Qinghai–Tibet freeway. A high-precision macro wind velocity detector was employed to study the natural convective characteristics of both types of rock layers and their differences. The natural convection velocity in both types of rock layers resulting from the temperature difference was investigated for the first time through modeling experiment. Natural convection velocity in the hollow concrete brick layer with weak convection resistance was higher than that in the crushed rock layer. Their maximum velocities were 0.10 m/s and 0.08 m/s, respectively. The different heat transfer processes and their intensities resulting from the boundary temperature fluctuations were the primary reasons for inner asymmetric temperature fluctuation and decline. The cooling process closely related to convection time and convection velocity. The temperature difference was the key factor in the occurrence of convection and its intensity change, although the air temperature changes also had an effect on the airflow process. The occurrence of natural convection required a start-up temperature difference. Moreover, a linear relationship was observed between natural convection velocity and temperature difference. |
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