Journal of the Japan Institute of Energy
Online ISSN : 1882-6121
Print ISSN : 0916-8753
ISSN-L : 0916-8753
Volume 85, Issue 7
Displaying 1-3 of 3 articles from this issue
  • Naotake HIRAO, Hideyuki OHTAKI, Toshiroh Karaki DOY, Masahiro MATSUO
    2006 Volume 85 Issue 7 Pages 525-530
    Published: July 20, 2006
    Released on J-STAGE: June 28, 2010
    The Stirling engine is an external combustion engine run by the expansion and contraction of an operating gas by heat, regardless of the source of heat. It used to be called “The Dream Engine” as it is noiseless and is as efficient as the Carnot type in theory. The Stirling engine has been given more credit recently because of its promising characteristics as a clean engine regardless of heat source, with possibili-ties of becoming an ecologically sound engine. Unfortunately, techniques to minimize losses of various natures have not been established yet, even in theory, yet using present machining techniques, which are essential in obtaining high engine efficiency. Our focus was the structure of the frame, in order to increase the efficiency and output of the Stirling engine. Conventionally, frames of monocoque construction were fabricated through machining, which was limited, as to shape, by manufacturing techniques. With an aim to improve the specific output of the Stirling engine, the author, et al proposed a laminated structure frame using two different materials, which made the Stirling engine drastically lighter than the conventional Stirling engine using a monocoque frame. In terms of heat transmission, the laminated frame also presented excel-lent characteristics, proving that it could provide a higher pressure ratio than the monocoque-framed Stirling engine, working advantageously in improving overall output.
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  • Tomoko IWATA, Yutaka GENCHI, Sohei SHIMADA
    2006 Volume 85 Issue 7 Pages 531-541
    Published: July 20, 2006
    Released on J-STAGE: June 28, 2010
    We developed a simulation model for optimizing the efficient use of livestock manure system taking into account of supply-demand balance of fertilizer. This model made it possible to calculate the most effective combination of livestock manure disposal systems and fertilizer transportation systems to minimize the total cost of disposal for a given maximum permitted total GHG emission from disposal and transportation sys-tems. In this study, we proposed an efficient use system of livestock manure by using this optimization model in Iwate Prefecture. The result of the simulation indicated that manure heaped in a field should be utilized as a fertilizer to reduce GHG emission because GHG increase from disposal system and fertilizer transportation was less than GHG reduction by elimination of field heaping and decrease in the usage of chemical fertilizer. And a result of sensitivity analysis to variables in the optimization model for livestock manure disposal system showed that the fluctuations of compost and woodchip price, and manure emission style of especially beef cow and pig strongly influenced on the optimal selection of disposal technology rather than that of electricity price.
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  • High Speed Fermentation Process
    Hiroshi IWASAKI, Nobuhide TAKAHASHI, Atsushi KOBAYASHI, Koichi YAMADA
    2006 Volume 85 Issue 7 Pages 542-551
    Published: July 20, 2006
    Released on J-STAGE: February 23, 2011
    Biomass is a carbon neutral material and the development of processes for the use of the bioethanol is accelerating worldwide as the demand for its use as an alternate transportation fuel increases. The bioethanol has various advantages in the fuel performances of the environmental and the octane number, etc. But the amount of heat of combustion for each unit volume is about 70% of gasoline, the price of bioethanol is necessary to be less than 70% of the gasoline with competitive for gasoline. It is assumed a current gasoline refinery cost is about Y40/L (crude oil, $50/bbl). The ethanol production cost is preferable to be less than Y20/ kg to be competitive to gasoline cost. Then the rationalization of the bioethanol process is necessary. The examination of the use of the lignocellulosic biomass with the possibility of cheap and a large amount of supply as a raw material biomass and the rationalization in the process are necessary. We reported on the rationalization process in the refinement process of the bioethanol by the former report. Herein, the design of a high speed fermentation process which uses recombinant Coryneform type bacteria transformed by a recombinant DNA technology for the cost reduction is reported. A high speed fermentation of 30kg-ethanolm-3·h-1 was assumed by the application of a high bacteria concentration of 30wt% (wet base). The produc-tion cost including both fixed and variable cost of the newly designed process was evaluated at an annual production rate of 206, 000t-ethanol. The resulting cost was compared with the production cost using a future NREL (National Renewable Energy Laboratory) process. The high speed fermentation process, whose reten-tion time was 1.7h, required smaller volume of fermentators than those for NREL process by 5%. This reduced the investment cost by Y0.3/kg-ethanol compared to that of NREL process. The variable cost of the new process could be reduced by Y1.1/kg-ethanol. Further research work to attain the above cost reduction is for the confirmation of high bacteria concentration fermentation with low nutrient dose.
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