Journal of the Japan Institute of Energy
Online ISSN : 1882-6121
Print ISSN : 0916-8753
ISSN-L : 0916-8753
Volume 89 , Issue 11
Showing 1-3 articles out of 3 articles from the selected issue
Original Paper
  • Taeko AOE, Ryoichi YAMAMOTO, Toshiharu IKAGA, Yasuyuki KONDO, Yuichi M ...
    2010 Volume 89 Issue 11 Pages 1070-1087
    Published: 2010
    Released: December 28, 2010
    This paper proposes a new method for evaluating the eco-efficiency of a household based on Factor X, which was proposed by Yamamoto and colleagues in 1999. We had proposed methods for evaluating Factor X of a household which consists of a building and home appliances, and implemented empirical evaluations. However, there remained the following two issues to be considered. One is how to quantify the function of a household. The other is how to take account of the so-called synergy effects. It proposes the method for calculating the overall functions of one household using the purchasing price as a weighting coefficient. This method is the same as Laspeyres quantity index in economics fields. As a synergy effect, the insulating effect in the building, etc. are considered. The result showed that the annual greenhouse gas emission of a typical household drastically decreased by 52.2% from 1990 to 2009 while the aggregated function of the household slightly decreased by 0.2% during the same period so that Factor X was 2.1 with respect to global warming. It was thus shown quantitatively that Factor X of households in Japan presumably improved during the period although only limited assessments were implemented.
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  • Kazutaka OHARA, Masayoshi TSUKIKAWA, Yousuke ARAKI, Akihiro HAYAKAWA, ...
    2010 Volume 89 Issue 11 Pages 1088-1094
    Published: 2010
    Released: December 28, 2010
    Spherically propagating laminar and turbulent flames at elevated pressures in a large volume chamber were studied for ethanol / air mixtures. The properties of the ethanol flame at elevated pressures, especially the burning velocity and the effects of the flame stretch acting upon it are quit important for the modeling of combustion in internal combustion engines. Experiments were carried out in the wide range of the equivalence ratio from 0.8 to 1.4 at two turbulence intensities of 0.80 and 1.59m/s varying the initial pressure from 0.10 to 0.50MPa. The unstretched laminar burning velocity decreased with increasing initial pressure. The ratio of turbulent burning velocity to unstretched laminar burning velocity increased with increasing the turbulence Karlovitz number. This ratio of the burning velocities was large for rich flames. Thermo-diffusive effects might be more influential to rich ethanol flames because of their small Lewis number. The ratio of turbulent to laminar burning velocity was also found to increase with increasing initial pressure.
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Technical Paper
  • Shogo ISHII, Soichiro IKEGAMI, Hiroshi TERAO, Taisuke ONO, Yasuyuki HA ...
    2010 Volume 89 Issue 11 Pages 1095-1102
    Published: 2010
    Released: December 28, 2010
    This study is intended to develop the waste heat recovery generation system using steam-Rankine cycle for co-generation system with a small capacity prime mover in the range of about 500 kW or less. In our previous reports, a scroll expander has attracted attention as a power recovery device which has high efficiency potential even in the case of small power capacity, and the performance characteristics of it are investigated through the experiments. Then, it was confirmed that the leakage loss at the beginning of expansion process and the thermal loss cause the performance of the scroll expander to decrease. Therefore, in this paper, the shape of the orbiting scroll was redesigned to prevent the leakage, and also the type of the scroll expander was changed from symmetric scroll to asymmetric scroll which had high expansion ratio for high-power and high-performance. As a result, the expander performance was improved by the reduction of the leakage and the increase of the net power, and the expander efficiency reached up to 60.8 % at the maximum under the experimental conditions that the suction pressure of working fluid was 590 kPa and the revolution speed was 1950 rpm.
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