Cooling Dynamics of Wet Clothing

Protective clothing is frequently used to provide safety and comfort for persons exposed to various temperature environments. Water absorbed by clothing can significantly influence the heat transfer characteristics of the clothing material. Understanding the dynamics of evaporative fabric cooling is important in the development of new garments. To investigate the cooling dynamics associated with wet clothing, a series of experiments was conducted to document the cooling created by single and multi-layered fabric samples exposed to controlled temperature, humidity and airflow conditions. The results revealed that the onset and the magnitude of evaporative cooling are determined by the amount of water absorbed in a fabric. The number of fabric layers used in turn, determines the amount of water retained within a material. This information can now provide the basis for determining the number of fabric layers to be used in new garment design and development

Multi-sector thermo-physiological head simulator for headgear research

[EN] A novel thermo-physiological human head simulator for headgear testing was developed by coupling a thermal head manikin with a thermo-physiological model. As the heat flux at head-site is directly measured by the head manikin, this method provides a realistic quantification of the heat transfer phenomena occurring in the headgear, such as moisture absorption-desorption cycles, condensation, moisture migration across clothing layers. Before coupling, the opportunities of the head manikin for representing the human physiology were evaluated separately. The evaluation revealed reduced precision in forehead and face temperature predictions under extreme heterogeneous temperature distributions and no initial limitation for simulating temperature changes observed in the human hysiology.This work has been supported by the State Secretariat for Education, Research and Innovation (SBFI C11.0137) under the grant COST Action TU1101 project (http://www.bicycle-helmets.eu/) The authors gratefully acknowledge Dr. Matthew Morrissey and Rolf Stampfli from Empa (St. Gallen, Switzerland) for their valuable contribution to programming of the coupling interface and Barbara Koelblen from Empa (St. Gallen, Switzerland) and Warsaw University of Technology (Warsaw, Poland) for providing the validation data and consultation.Martínez Guillamón, N.; Psikuta, A.; Corberán, JM.; Rossi, RM.; Annaheim, S. (2017). Multi-sector thermo-physiological head simulator for headgear research. 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Post-exercise cooling techniques in hot, humid conditions

Aim: To investigate the effect of task familiarisation on the spontaneous pattern of energy expenditure during a series of 2000 m cycling time trials (TTs). Method: Nine trained males completed three 2000 m TTs on a Velotron cycling ergometer. To examine pacing strategy, the data were assigned to 250 m “bins,” with the pattern of aerobic and anaerobic energy expenditure calculated from total work accomplished and gas-exchange data. Results: There were no significant differences between trials in performance times (191.4 (SD 4.3), 189.4 (4.6), 190.1 (5.6) s), total aerobic (58.3 (2.7), 58.4 (3.1), 58.0 (3.4) kJ) and total anaerobic energy expenditure (16.4 (3.3), 17.3 (2.8), 16.5 (3.1) kJ). Pacing strategy in the second and third TT differed from the first TT in that a lower power output was adopted during the first 500 m, enabling a higher power output during the final 750 m of the TT. This adjustment in the pattern of energy expenditure was mediated by an alteration in the pattern of anaerobic energy expenditure, which paralleled changes in total energy expenditure. Furthermore, participants retained an anaerobic energy “reserve” enabling an end-spurt during the second and third trials. Conclusion: Small modifications to the pacing strategy are made following a single bout of exercise, primarily by altering the rate of anaerobic energy expenditure. This may have served to prevent critical metabolic disturbances. The alteration in pacing strategy following the first exercise bout is compatible with a complex intelligent regulatory system