2023 Fiscal Year Research-status Report
Measurement of the Cooling Effect of a Water Mist Fan on Personal Protection Equipment(PPE) and Work Clothing
| Project/Area Number |
21K04567
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| Research Institution | Osaka Metropolitan University |
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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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| Keywords | mist cooling / heat stroke / worker / PPE / clothing / evaporation |
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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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| Causes of Carryover |
Research results currently under submission. Remaining funds to be used to help pay Open Access fee.
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