Evaporative resistance of newly designed bicycle helmets
© Kuklane et al. 2015
Published: 14 September 2015
As a continuation of the work on the ventilation requirements for a bicycle helmet for commuters , 15 full scale helmet mock-ups were created and tested for dry heat loss properties  in a wind tunnel on a thermal head manikin . This paper presents the results of the wet heat transfer measurements in the form of evaporative resistance.
The helmets were tested in the wind tunnel placed in a climatic chamber at 34 °C and 40 % relative humidity (water vapour pressure in the air 2200 Pa) with the air velocities set to 1.6 m/s (≈6 km/h). Tests were performed on the head model without a wig. Evaporative resistance was calculated from heat loss corrected for the difference in head surface to textile skin temperature . One (TK) of the 15 mock-ups was tested back to front, too (TKo). In addition, 4 commercially available helmets were tested as reference. Three of them were one of the best, one average and one of the less well performing helmets of the study by Brühwiler et al. , and one was a helmet often bought and used by commuters.
The best reference helmet from the earlier study  stayed approximately in the middle of the tested range while the poorest reference helmet was in the end of the line with an often used one as the worst (Figure 1). Thus, the newer solutions performed much better from an evaporation viewpoint than commercially available helmets. However, the order of the helmets in the "best function line" for evaporation was different from their insulation performance, as reported previously .
The best helmet from the evaporation viewpoint was different from the best in terms of insulation. This means that a best solution for a commuter has to be defined by the user's bicycling activity, the weather conditions etc. The newly designed helmets' results can be used as the basis for improvement of helmet ventilation.
- Kuklane K, Heidmets SS, COST Action TU1101 WG4: User friendly bicycle helmet for commuters. Proceedings of the International Cycling Safety Conference. 2013, Helmond, The Netherlands, 4- , 20-21 November 2013Google Scholar
- Aljaste H, Kuklane K, Heidmets SS: COST Action TU1101 WG4. Better Bicycle Helmets for Commuters - Evaluation of Ventilation. Proceedings of the International Cycling Safety Conference. 2014, 18-19 November 2014, Gothenburg, Sweden, 7-Google Scholar
- Liu X, Holmér I: Evaluation of evaporative heat transfer characteristics of helmets. Applied Human Science. Journal of Physiological Anthropology. 1997, 16 (3): 107-113.PubMedGoogle Scholar
- Wang F, Kuklane K, Gao C, Holmér I: Development and validity of a universal empirical equation to predict skin surface temperature on thermal manikins. Journal of Thermal Biology. 2010, 35 (4): 197-203. 10.1016/j.jtherbio.2010.03.004.View ArticleGoogle Scholar
- Brühwiler PA, Buyan M, Huber R, Bogerd CP, Sznitman J, Graf SF, Rösgen T: Heat transfer variations of bicycle helmets. Journal of Sports Sciences. 2006, 24 (9): 999-1011. 10.1080/02640410500457877.View ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.