Journal of the Japan Institute of Energy
Online ISSN : 1882-6121
Print ISSN : 0916-8753
ISSN-L : 0916-8753
Volume 85 , Issue 5
Showing 1-3 articles out of 3 articles from the selected issue
  • Yadong NING, Yutaka TONOOKA, Hailin Mu, Yasuhiko KONDO, Weisheng ZHOU
    2006 Volume 85 Issue 5 Pages 371-380
    Published: May 20, 2006
    Released: June 28, 2010
    In this paper, trends in the energy consumption structure of urban households in China are analyzed over two decades, using the China Family Income and Expenditure Survey from 1981 to 2000. The yearly trends consist of three elements: effective energy consumption per capita, energy efficiency, and population size. The underlying factors that affect these trends, such as change of life style, income levels, and fuel switching are also considered. The total energy consumption of this sector increased from 1166 PJ/year in 1981 to 2527 PJ/year in 2000. The trend in average energy consumption saw a decrease from 5.78GJ/year·capita in 1981 to 5.50 GJ/year·capita in 2000, but the effective energy consumption increased from 1.55GJ/ year·capita in 1981 to 2.81GJ/year·capita in 2000. Averaged energy efficiency increased from 27% in 1981 to 51% in 2000. In 2000 47% of total energy consumption was from coal, 15% from LPG, 9% from city-gas and, 19% from electricity, of this 44% was used for space heating, and 39% for cooking and hot water supply. In part-II of this paper a regional (provincial) analysis is undertaken.
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  • Hidetoshi YAMAMOTO, Masayoshi SADAKATA
    2006 Volume 85 Issue 5 Pages 381-389
    Published: May 20, 2006
    Released: June 28, 2010
    The objectives of this study are to evaluate the gasification reactivity of a mixture of coal/biomass using a thermogravimetry (TG) apparatus. The experiments have been performed with biobriquette contain-ing pulp black liquor (0-15wt%). A char is initially formed by pyrolysis of the samples for an hour under helium gas stream at different temperatures (973-1373K), and subsequently gasified with an oxidizer (CO2, H2O) for another an hour at the same temperatures as in pyrolysis.
    The results show that; (1) The gasification reactions of the samples with CO2 or H2O are first-order with respect to the conversion of char, and the rates can be expressed by Arrhenius equation {k=A exp (-E/RT)}. Furthermore, the gasification at the lower concentrations (2-20vol%) of CO2 obeys the Langmuir-Hinshelwood reaction mechanism.(2) The addition (5-15wt%) of pulp waste to biobriquette had a greater effect on increas-ing (2-3 times) the gasification rates.(3) This effect may be due to catalysis by alkaline metal (Na) involved in pulp waste.
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  • Atsuhiro KAWAMURA, Atsushi AKISAWA, Takao KASHIWAGI, Shuichi HARADA, N ...
    2006 Volume 85 Issue 5 Pages 390-397
    Published: May 20, 2006
    Released: June 28, 2010
    In greenhouses for crop production in Japan, large-scale/intensive management has advanced in recent years due to price competitiveness for import crops and the structural shortage of workers, and energy-conserving measures have become an important issue.
    The purpose of this study was to provide practical strategies for application of Combined Heat and Power, CHP in short, to effective energy conservation in greenhouses. The authors have performed energy demands measurement at existing large tomato greenhouses in Japan for 4 years, and investigated the effectiveness of CHP operated for the greenhouses. Model analysis revealed the following results.
    (1) The ratio of Heat to electricity in the greenhouses is zero in all time zones except the carbon dioxide Fertilization time in summer while 60 during maximum Heating time in winter, showing a particular characteristic of energy consumption in greenhouses.
    (2) Relatively larger-sized CHPs are useful for larger-scale greenhouses to attain the energy conservation rate of 3 to 4%.
    (3) From the economic aspect of tomato production, the scale of greenhouse should be 5×104m2 or more, and gas engine CHP is superior to micro gas turbine. Combined use of a boiler is necessary to satisfy heat demands and carbon dioxide fertilization.
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