| Project/Area Number |
16380173
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Agricultural environmental engineering
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| Research Institution | National Agricultural Research Organization (2006-2007)
National Institute for Rural Engineering (2004-2005) |
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Principal Investigator |
SASE Sadanori National Agricultural Research Organization, National Institute for Rural Engineering, Department of Rural Technologies, Team Leader (80373223)
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| Co-Investigator(Kenkyū-buntansha) |
ISHII Masahisa National Agriculture and Food Research Organization, National Institute for Rural Engineering, Department of Rural Technologies, Senior Researcher (10343766)
IKEGUCHI Atsuo National Agriculture and Food Research Organization, National Institute of Livestock and Grassland Science, Livestock Research Team on Global Warming, Chief Researcher (10222415)
KURATA Kenji University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor (90161736)
KANEKO Keiko University of Tokyo, Graduate School of Agricultural and Life Sciences, Assistant Professor (50332599)
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| Project Period (FY) |
2004 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥14,360,000 (Direct Cost: ¥13,700,000、Indirect Cost: ¥660,000)
Fiscal Year 2007: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2004: ¥7,500,000 (Direct Cost: ¥7,500,000)
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| Keywords | semiarid region / controlled environment agriculture / optimum environmental control / cooling / ventilation / light quality / stress / saving water consumption |
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| Research Abstract |
The overall goal of this project was to develop an effective environmental control strategy to provide a suitable greenhouse environment for plant production and minimize the water use in semiarid climate. Experiments were conducted using two single-span double-polyethylene greenhouses at CEAC, the University of Arizona. Results of fog cooling in combination with natural ventilation showed that the inside relative humidity decreased with an increase in ventilation rate as expected from the predictions, while the water use for fog cooling increased. A simple control algorithm was to optimize the ventilation rate and fog generation rate proposed and it demonstrated a possibility of maintaining relative humidity and air temperature simultaneously within a desirable range while reducing the water use. Airflow visualization using bubble indicated typical airflow patterns under fogging. Measurements of light quality showed that the red/far red ratio decreased gradually with the depth into the canopy in the passage, while the ratio in the rows took the minimum value at the middle of the height. Wind tunnel tests were conducted for a 1/15 scale model of the same greenhouse. It was found that the best configuration for providing the inside airflow was achieved when the roof and side vents were open and the roof opening faced to the leeward. When only the roof vent was open and the opening faced to the windward, an air circulation with reverse flow above the floor was induced. Although there was no significant difference in the mean inside temperature based on wind direction, the center and leeward sections were significantly greater when the roof opening faced to the leeward. The insect screen installed on the vent openings reduced the inside air speed to 40-68% of the air speed for non-screened vents.
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