| Project/Area Number |
21K04567
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 25020:Safety engineering-related
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| Research Institution | Osaka Metropolitan University (2022-2023)
Osaka City University (2021) |
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Principal Investigator |
Farnham Craig 大阪公立大学, 大学院生活科学研究科, 准教授 (60638245)
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| Project Period (FY) |
2021-04-01 – 2025-03-31
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| Project Status |
Granted (Fiscal Year 2023)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2023: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
Fiscal Year 2022: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000)
Fiscal Year 2021: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | mist cooling / heat stroke / worker / PPE / clothing / evaporation / mist / cooling / Mist / Cooling / Worker safety / Heat stress / Heat stroke / evaporation cooling |
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| Outline of Research at the Start |
熱ストレスと熱射病は、暑い環境で保護服を着用する労働者にとって危険である。 作業員が防護服を脱いだり、屋内で空調された部屋に移動したりする必要としない、現場での熱ストレス緩和が必要である。
ミストファンは、高温環境で低コストで強力な冷却効果を発揮します。 衣類は冷却効果の一部をブロックする。 作業服で覆われたときの皮膚に対するこの冷却効果の特性評価をする。 これにより、ミストファンを効果的に使用して作業者の熱ストレスを軽減する方法を決定できる。皮膚のような加熱表面に対するミストファンの冷却効果を測定する。 表面は作業服または個人用保護具で覆われる。
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| Outline of Annual Research Achievements |
Full analysis of the large amount of data from FY2022 was supplemented by more precise experiments in FY2023 using more uniform cloth samples and a level heated surface using parts of the FY2022 thermal mannequin system.
Heat flux and temperature measurements yielded overall heat transfer coefficients for work clothes, both dry and wet, both with and without PPE. Total cooling ranged about 40 to 160 W/m2, depending on body location and distance from fan. Thus the mist fan cooling can provide significant cooling to largely counter metabolic heat generated by people doing light labor.
The extra cooling by wetting and flash evaporation was derived by comparing heat flux from non-mist fan and its overall heat transfer coefficient(h) vs. mist fan heat flux. Temperature measurements are not reliable in mist, so taking wet bulb as lowest possible air temperature, and h from the non-mist fan, the excess heat flux must be due to wetting and flash evaporation. This was about 20 to 75W/m2 extra cooling by flash evaporation beyond that of the cooled air forced convection. Secondary wetting (not from sweat) must be introduced into standard models of human heat exchange and thermal comfort to account for this.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Heat transfer coefficients for work clothes and PPE, both wet and dry were found from a total 18 days of outdoor experiment data, with supplemental small scale experiments in FY2023. Full results are summarized in a paper in submission, under peer review. Remaining FY2023 funds were extended to FY2024 to help pay the Open Access fee.
Publications:
1. Farnham,C.ミストファンの冷却効果に対する作業服と防護服の影響に関する実験 、日本建築学会大会（近畿）2023/9/15
1. Farnham,C. "Measurements of the Effect of Work Clothing and Personal Protective Equipment(PPE) on the Cooling Effect of a Mist Fan" 空気調和・衛生工学会大会（福井）2023/9/06
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| Strategy for Future Research Activity |
The results yielded valuable heat transfer coefficient data which is being incorporated into a CFD model. As this CFD model progresses, it is necessary to compare results to standard human thermal models (2-node model and more complex models) as well as human test subjects.
More detailed research is needed into the transient effect of wetting of clothes, their saturation, drying, and effect on cooling by mist. Modification of standard models to account for wettedness not produced by sweat is needed. Kakenhi funding request on this point was rejected. Looking for other sources.
Measurements of wind speed in mist using the ultrasonic anemometer also yielded sonic temperature data, which is now being investigated as a potential method to much more accurately evaluate mist cooling effects.
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