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- Liu, Minzhang, et al.
(författare)
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The environment and energy consumption of a subway tunnel by the influence of piston wind
- 2019
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Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 246, s. 11-23
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Tidskriftsartikel (refereegranskat)abstract
- With the flourishing development of the subway construction, it becomes increasingly urgent to improve the subway tunnel environment and reduce the energy consumption of the tunnel ventilation system. The tunnel environment is significantly affected by the piston wind, which is influenced by the train speed. In this paper, a three-dimensional computational model of a subway tunnel is developed and validated through experiments. The model is used to study the carbon dioxide concentration and thermal environment of the subway tunnel. The optimal train speed is proposed with the aim to minimize the volume of mechanical supply air and to optimize the carbon dioxide concentration and thermal environment of the tunnel. In parallel with the considerations of tunnel environment, the subways in 25 cities of China are analyzed to study the energy conservation of the tunnel ventilation system by making full use of piston wind. The results indicate that the optimal train speed is 30 m/s based on the carbon dioxide concentration and thermal environment. The effective utilization of the piston wind can reduce 13% similar to 32% of the energy consumption for tunnel ventilation. The calculation method of the optimal train speed developed in this paper is also applicable to ordinary railway tunnels and high-speed railway tunnels.
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| 3. |
- Wu, Zhenjing, et al.
(författare)
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Mathematical Modeling and Performance Analysis of Seawater Heat Exchanger in Closed-Loop Seawater-Source Heat Pump System
- 2019
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Ingår i: Journal of energy engineering. - : ASCE-AMER SOC CIVIL ENGINEERS. - 0733-9402 .- 1943-7897. ; 145:4
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Tidskriftsartikel (refereegranskat)abstract
- The seawater source heat pump (SWHP) utilizes low-grade energy from seawater to satisfy heating/cooling requirements of coastal buildings. Compared with the open-loop SWHP system, the closed-loop system is more stable and reliable when used in cold regions because the seawater heat exchanger can mitigate icing and corrosion problems. This study established mathematical modeling for the seawater heat exchanger, which was validated by the experimental results, to estimate the heat transfer performance. The thermal performance of the seawater heat exchanger under different operating conditions was predicted, and the effects of several key parameters on thermal resistance were analyzed. The results revealed that the pipe wall thermal resistance of the original heat exchanger was the most important factor limiting the heat transfer. Hence, a cost analysis of the heat exchangers with different pipe materials was conducted, and the steel pipe with anticorrosive coating was proven to be optimal in reducing pipe wall thermal resistance and economy. The findings are useful in designing and optimizing the seawater heat exchanger and promoting the application of ocean thermal energy.
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