Evaluation of thermal and evaporative resistances in cricket helmets using a sweating manikin

Pang, Toh Yen; Subic, Aleksandar; Takla, Monir

doi:10.1016/j.apergo.2013.04.011

Cited by 18 publications

(9 citation statements)

References 32 publications

(48 reference statements)

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“…From the frontal zonal evaporative-heat-loss plots (Figure 8), it can be observed that the helmets transmitted 70%-85% of the evaporative heat at 3 m/s and 88-98% at 6 m/s (as compared to nude manikin). These values are comparable with the evaporative-heat-transfer results from a study [36] on cricket helmets that showed helmets dissipated 68-78% of the evaporative heat. Considering that the study [36] was carried out at a very low velocity (0.2 m/s) for cricket helmets (different from bicycle helmets), it can be presumed that high evaporative-heat-dissipation values recorded in the current study from the scalp and face zones are due to higher air velocities used in testing.…”

Section: Zonal Heat Transfer Characteristicssupporting

confidence: 85%

“…Several works in the literature [50][51][52] show the effect of air flow on heat transfer between body and environment, and its importance in understanding thermal performance. The chosen conditions are a closer representation of the real-use conditions of helmets because, as indicated in another study [36], resistance values obtained in static conditions are likely overestimations of actual resistances surrounding a rider's head during normal bicycle use.…”

Section: Limitations and Considerationsmentioning

confidence: 99%

“…Thermal manikins have been consistently used to analyze different heat-transfer modes. The convective characteristics of helmets have been studied in detail using manikins: To assess the influence of comfort-angle on helmet ventilation [30], to evaluate the global and local characteristics of bicycle helmets [31], to evaluate helmet-design parameters [32], to understand rowing head-gear characteristics [33], for local ventilation-efficiency quantification [34], to quantify variation among helmets and helmet-ventilation efficiency [35], convective characteristics of cricket helmets [36], and ventilation changes in full-face motorcycle helmets [37] and industrial helmets [23,27]. Thermal manikins were also used in evaluating the radiant heat-transfer characteristics of rowing head gear [33] and bicycle helmets [38] in combination with forced convection.…”

Section: Introductionmentioning

confidence: 99%

“…Thermal manikins were also used in evaluating the radiant heat-transfer characteristics of rowing head gear [33] and bicycle helmets [38] in combination with forced convection. Evaporative heat-transfer helmet characteristics were also studied using thermal manikins in pure evaporation studies for cricket helmets [36], and in combination with convection for industrial helmets [23,27]. However, combined convective and evaporative heat-transfer studies using a biofidelic thermal manikin have not been performed.…”

Section: Introductionmentioning

confidence: 99%

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Thermal-Performance Evaluation of Bicycle Helmets for Convective and Evaporative Heat Loss at Low and Moderate Cycling Speeds

et al. 2019

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The main objective of the study was to investigate the thermal performance of five (open and closed) bicycle helmets for convective and evaporative heat transfer using a nine-zone thermal manikin. The shape of the thermal manikin was obtained by averaging the 3D-point coordinates of the head over a sample of 85 head scans of human subjects, obtained through magnetic resonance imaging (MRI) and 3D-printed. Experiments were carried out in two stages, (i) a convective test and (ii) an evaporative test, with ambient temperature maintained at 20.5 ± 0.5 °C and manikin skin temperature at 30.5 ± 0.5 °C for both the tests. Results showed that the evaporative heat transfer contributed up to 51%–53% of the total heat loss from the nude head. For the convective tests, the open helmet A1 having the highest number of vents among tested helmets showed the highest cooling efficiency at 3 m/s (100.9%) and at 6 m/s (101.6%) and the closed helmet (A2) with fewer inlets and outlets and limited internal channels showed the lowest cooling efficiency at 3 m/s (75.6%) and at 6 m/s (84.4%). For the evaporative tests, the open helmet A1 showed the highest cooling efficiency at 3 m/s (97.8%), the open helmet A4 showed the highest cooling efficiency at 6 m/s (96.7%) and the closed helmet A2 showed the lowest cooling efficiency at 3 m/s (79.8%) and at 6 m/s (89.9%). Two-way analysis of variance (ANOVA) showed that the zonal heat-flux values for the two tested velocities were significantly different (p < 0.05) for both the modes of heat transfer. For the convective tests, at 3 m/s, the frontal zone (256–283 W/m2) recorded the highest heat flux for open helmets, the facial zone (210–212 W/m2) recorded the highest heat flux for closed helmets and the parietal zone (54–123 W/m2) recorded the lowest heat flux values for all helmets. At 6 m/s, the frontal zone (233–310 W/m2) recorded the highest heat flux for open helmets and the closed helmet H1, the facial zone (266 W/m2) recorded the highest heat flux for the closed helmet A2 and the parietal zone (65–123 W/m2) recorded the lowest heat flux for all the helmets. For evaporative tests, at 3 m/s, the frontal zone (547–615 W/m2) recorded the highest heat flux for all open helmets and the closed helmet H1, the facial zone (469 W/m2) recorded the highest heat flux for the closed helmet A2 and the parietal zone (61–204 W/m2) recorded the lowest heat flux for all helmets. At 6 m/s, the frontal zone (564–621 W/m2) recorded highest heat flux for all the helmets and the parietal zone (97–260 W/m2) recorded the lowest heat flux for all helmets.

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Section: Zonal Heat Transfer Characteristicssupporting

confidence: 85%

Section: Limitations and Considerationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal-Performance Evaluation of Bicycle Helmets for Convective and Evaporative Heat Loss at Low and Moderate Cycling Speeds

et al. 2019

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“…It is also important to note the effects of regional ensemble changes that may impact human thermoregulation (e.g., use of body armor plates). Being divided into 20 independent zones, the thermal manikin allows for some regional analysis, specific to items of clothing (e.g., torso and BA, head and helmets) [ 29 ]. These independent zones of the manikin can provide clo and i m measures specific to each and each section can be accounted for by their relative surface area.…”

Section: Discussionmentioning

confidence: 99%

Biophysical Assessment and Predicted Thermophysiologic Effects of Body Armor

et al. 2015

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IntroductionMilitary personnel are often required to wear ballistic protection in order to defend against enemies. However, this added protection increases mass carried and imposes additional thermal burden on the individual. Body armor (BA) is known to reduce combat casualties, but the effects of BA mass and insulation on the physical performance of soldiers are less well documented. Until recently, the emphasis has been increasing personal protection, with little consideration of the adverse impacts on human performance.ObjectiveThe purpose of this work was to use sweating thermal manikin and mathematical modeling techniques to quantify the tradeoff between increased BA protection, the accompanying mass, and thermal effects on human performance.MethodsUsing a sweating thermal manikin, total insulation (IT, clo) and vapor permeability indexes (im) were measured for a baseline clothing ensemble with and without one of seven increasingly protective U.S. Army BA configurations. Using mathematical modeling, predictions were made of thermal impact on humans wearing each configuration while working in hot/dry (desert), hot/humid (jungle), and temperate environmental conditions.ResultsIn nearly still air (0.4 m/s), IT ranged from 1.57 to 1.63 clo and im from 0.35 to 0.42 for the seven BA conditions, compared to IT and im values of 1.37 clo and 0.45 respectively, for the baseline condition (no BA).ConclusionBiophysical assessments and predictive modeling show a quantifiable relationship exists among increased protection and increased thermal burden and decreased work capacity. This approach enables quantitative analysis of the tradeoffs between ballistic protection, thermal-work strain, and physical work performance.

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A Review on Thermal Comfort Evaluation of Head-Worn Devices

Chen

2018

Advances in Ergonomics in Design

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Evaluation of thermal and evaporative resistances in cricket helmets using a sweating manikin

Cited by 18 publications

References 32 publications

Thermal-Performance Evaluation of Bicycle Helmets for Convective and Evaporative Heat Loss at Low and Moderate Cycling Speeds

Thermal-Performance Evaluation of Bicycle Helmets for Convective and Evaporative Heat Loss at Low and Moderate Cycling Speeds

Biophysical Assessment and Predicted Thermophysiologic Effects of Body Armor

A Review on Thermal Comfort Evaluation of Head-Worn Devices

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