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Resistance-capacitance model of the capillary heat exchanger in subway tunnels
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作者 Zhen Tong Hao Wu +2 位作者 yiming guan Yongming Ji Songtao Hu 《Energy and Built Environment》 2024年第1期1-8,共8页
The subway operation generates a large amount of waste heat,which will lead to a disruption of the underground thermal balance.To remove the heat,a ground source heat pump system adopting capillary net as the front-en... The subway operation generates a large amount of waste heat,which will lead to a disruption of the underground thermal balance.To remove the heat,a ground source heat pump system adopting capillary net as the front-end heat exchanger can be built in the tunnels to recycle the waste heat and use it for building heating.Different simulation method was used to analyze the heat transfer process in the tunnel and the surrounding rock.The existing simulation method usually takes a long time for calculation and can not be used for a real-time regulation of the system.Based on the concept of thermoelectric analogy,a resistance-capacitance(RC)model was proposed for rapid prediction and analysis on the heat transfer of the capillary net in subway tunnel.The annual thermal response in the tunnel was analyzed,and the influence of the tunnel air temperature and the capillary inlet water temperature was examined using this model.The maximum heat transfer flux of the capillary in summer(release heat)and in winter(extract heat)was 55.27 W/m 2 and 38.33 W/m 2,respectively.The effect of capillary inlet water temperature was more remarkable than that of the tunnel air temperature on the capillary heat exchange process. 展开更多
关键词 Subway tunnel Heat pump Capillary heat exchanger Resistance-capacitance model
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企业杠杆率、中长期信贷与企业绩效 被引量:5
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作者 管弋铭 范从来 张淦 《会计与经济研究》 CSSCI 北大核心 2020年第3期68-80,共13页
信贷的期限结构对企业绩效具有重要影响,加强对非金融企业中长期信贷支持是提升企业绩效的重要手段。文章将企业杠杆率纳入中长期信贷与企业绩效关系的分析,研究表明:第一,当企业杠杆率处于中低区间时,中长期信贷能够显著提升企业绩效,... 信贷的期限结构对企业绩效具有重要影响,加强对非金融企业中长期信贷支持是提升企业绩效的重要手段。文章将企业杠杆率纳入中长期信贷与企业绩效关系的分析,研究表明:第一,当企业杠杆率处于中低区间时,中长期信贷能够显著提升企业绩效,当企业杠杆率过高时,中长期信贷对企业绩效的提升作用被削弱,但在中高杠杆率区间,对民营企业提供中长期信贷支持更能提升其绩效;第二,随着时间的推移,中长期信贷对企业绩效的提升作用不断走弱;第三,在一定杠杆率水平下,中长期信贷与企业绩效呈倒U型关系,且这一关系在中小企业、民营企业和高成长企业中更显著。 展开更多
关键词 中长期信贷 企业杠杆率 企业绩效 门限模型
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