CIESC Journal ›› 2015, Vol. 66 ›› Issue (11): 4304-4311.DOI: 10.11949/j.issn.0438-1157.20150617

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Analysis of heat transfer efficiency and rate inside fermentation tank with heating coil of biogas projects

ZHANG Shaopeng1, HAN Ruiping1, CHEN Jingjing1, ZHOU Jun2,3, LU Xiaohua1, WANG Changsong1   

  1. 1 State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009, Jiangsu, China;
    2 School of Biotechnology and Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu, China;
    3 Bioenergy Research Institute, Nanjing Tech University, Nanjing 211816, Jiangsu, China
  • Received:2015-05-15 Revised:2015-06-05 Online:2015-11-05 Published:2015-11-05
  • Supported by:

    supported by the National Basic Research Program of China (2013CB733500-3/4) and the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

沼气工程罐内盘管加热传热速率与效率分析

张少鹏1, 韩瑞萍1, 陈晶晶1, 周俊2,3, 陆小华1, 王昌松1   

  1. 1 南京工业大学材料化学工程国家重点实验室, 江苏 南京 210009;
    2 南京工业大学生物与制药工程学院, 江苏 南京 211816;
    3 南京工业大学生物能源研究所, 江苏 南京 211816
  • 通讯作者: 王昌松
  • 基金资助:

    国家重点基础研究发展计划项目(2013CB733500-3/4);江苏高校优势学科建设工程。

Abstract:

Heating coil inside the tank is widely used in biogas projects at home and abroad. The various factors affecting the heating and heat transfer of the tank were analyzed from the heat transfer efficiency and rate based on the first and the second laws of thermodynamics. It was found that from the view of the overall heat transfer coefficient, the thermal conductivity and wall thickness were comprehensive considered and then the maximum heat transfer rate was obtained with low speed mixing method by choosing the thick wall with the value of thermal conductivity of above 15 W·m-1·K-1. Meanwhile, the energy consumption of transfer process was analyzed from the view of heat transfer efficiency. It can be obtained that an appropriate increase in the inlet temperature of cold material can reduce the irreversibility of heat transfer and increase the utilization ratio of limited energy for heat transfer process with countercurrent mixing. Therefore, the high-efficient, energy saving and rational theoretical guidance was provided for biogas project using tank heating to achieve the unity of transfer heat rate and efficiency.

Key words: thermodynamics, biogas projects, tank coil heating, total heat transfer coefficient, heat conduction, exergy, heat transfer rate and efficiency

摘要:

国内沼气工程中广泛采用的加热方式——罐内盘管加热。从热力学角度出发,基于热力学第一、第二定律,对影响罐内加热的各因素从传热速率与传热效率方面进行分析。研究表明,从传热速率-总传热系数角度分析,选用热导率在 15 W·m-1·K-1以上的厚管壁管径,同时采用低转速的搅拌方式能实现最大化的传热速率。另外,从传热效率-有效能角度对传热过程进行能耗分析,在逆流搅拌下,提高冷物料进口温度可以减少换热的不可逆性,可增加传热过程有效能的利用率。研究结果为实现沼气工程罐内加热过程传热速率与效率统一,达到能量的最优化利用提供理论参考。

关键词: 热力学, 沼气工程, 罐内加热, 总传热系数, 热传导, 有效能, 传热速率与效率

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