Abstract
Body ventilation systems (BVS) are effective in reducing heat strain, but the amount of heat that a BVS removes from a human body is unclear. The purpose of this study was to propose a method for quantifying BVS cooling capacity using manikin evaluation and modeling. Cooling capacity was calculated as the product of maximum cooling potential and cooling efficiency. The maximum cooling potential is calculated as the difference in enthalpy between the air entering and exiting the BVS where the outlet air temperature is equal to skin temperature with a relative humidity of 100%. The cooling efficiency, defined as a ratio of the cooling capacity to the maximum cooling potential, can be determined through measurements on sweating thermal manikins. A BVS system was evaluated on a manikin with the ventilation fan ON (flow rate 4.7 L/s) or OFF under eleven ambient conditions. The measured cooling efficiencies were 0.31 ± 0.02 and almost constant. Using this cooling efficiency, the BVS cooling capacities at various skin temperature and ambient conditions were estimated. This two-step approach can be used to quantify BVS cooling effectiveness during physiology studies. First, the cooling efficiency is determined on sweating thermal manikins. Second, the cooling capacity is calculated from the skin temperature, ambient temperature and relative humidity. However, various factors may reduce the actual cooling provided by the BVS, and the calculated cooling capacity should be considered the upper limit for cooling.
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Acknowledgments
Approved for public release, distribution is unlimited. The opinions or assertions contained herein are the private views of the author(s) and are not to be construed as official or reflecting the views of the Army or the Department of Defense. Citations of commercial organizations and trade names in this report do not constitute an official Department of the Army or Department of Defense endorsement or approval of the products or services of these organizations. We would like to thank Drs. R. Hoyt, W. Santee and L. Berglund for reviewing this paper and Mr. Brad Laprise for providing the body ventilation system.
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Communicated by George Havenith.
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Xu, X., Gonzalez, J. Determination of the cooling capacity for body ventilation system. Eur J Appl Physiol 111, 3155–3160 (2011). https://doi.org/10.1007/s00421-011-1941-0
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DOI: https://doi.org/10.1007/s00421-011-1941-0