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Copyright of Journal of Refrigeration is the property of Journal of Refrigeration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Eleven phase change materials (PCMs) for cooling humans in heat-stressed conditions were evaluated for their cooling characteristics. Effects of packaging material and segmentation were also investigated. Sample packs with a different type PCM (water- and oil-based PCMs, cooling gels, inorganic salts) or different packaging (aluminum, TPU, TPU + neoprene) were investigated on a hotplate. Cooling capacity, duration, and power were determined. Secondly, a PCM pack with hexagon compartments was compared to an unsegmented version with similar content. Cooling power decreased whereas cooling duration increased with increasing melting temperature. The water-based PCMs showed a >2x higher cooling power than other PCMs, but were relatively short-lived. The flexible gels and salts did not demonstrate a phase change plateau in cooling power, compromising their cooling potential. Using a TPU or aluminum packaging was indifferent. Adding neoprene considerably extended cooling duration, while decreasing power. Segmentation has practical benefits, but substantially lowered contact area and therefore cooling power. [ABSTRACT FROM AUTHOR]

Air ventilation garments (AVGs) are reported to be effective in improving thermal comfort in hot environments in previous research. The purpose of this study was to develop AVGs with small fan panels and examine their cooling performance. Three AVGs equipped with more, much smaller sized ventilation fans were developed, including FFV (ten small fans all located on the front body), BBV (ten small fans all located on the back body), and FBV (six small fans located on the front body and four small fans located on the back body). Another garment, without ventilation fans but with the same structure and textile material, was made as a reference garment (CON). The cooling performance of the four garments was examined through subject trials in a moderately hot environment of 32 °C and 60% relative humidity. Simulated office work with 70 min of sedentary activity was performed. The results showed that the physiological indexes of the mean body skin temperature, the mean torso skin temperature, and the heart rate in the three AVG scenarios were significantly lower than those in the CON condition (p < 0.05). Thermal sensation, thermal comfort, and wetness sensation were also improved when wearing the three AVGs (p < 0.05). No significant difference was displayed among the three AVGs on the whole body and the whole torso (p > 0.05) due to the similarity of the air velocity created by the fan panels. A significant difference was found on the local torso skin, with FFV significantly reducing the chest and the belly skin temperature, and BBV significantly reducing the scapula and the lower back skin temperature (p < 0.05). This study indicates that the AVGs with the small fan panels were effective in reducing heat strain and improving thermal comfort, and thus are recommended for use in hot environments. [ABSTRACT FROM AUTHOR]

Objectives: This study examined whether a fan‐attached jacket (FAJ) may mitigate the heat strain in hot or humid environment. Methods: Nine healthy men engaged in 60‐min sessions on a bicycle ergometer (4 metabolic equivalents [METs] workload) in hot‐dry (40°C and 30% relative humidity) and warm‐humid (30°C and 85% relative humidity) environments. Both are equivalent to an approximately 29°C wet‐bulb globe temperature. The experiment was repeated—once wearing an ordinal jacket (control condition) and once wearing a long‐sleeve FAJ that transfers ambient air at a flow rate of 12 L/s (FAJ condition)—in both environments. Results: Increases in core temperatures in hot‐dry environment were not statistically different between control and FAJ; however, that in the warm‐humid environment were significantly different between control and FAJ (0.96 ± 0.10°C and 0.71 ± 0.11°C in rectal temperature, P <.0001; and 0.94 ± 0.09°C and 0.61 ± 0.09°C in esophageal temperature, P <.0001). Changes in heart rate were different between control and FAJ in both environments (62 ± 3 bpm and 47 ± 7 bpm, P <.0001 in hot‐dry environment; and 61 ± 3 bpm and 46 ± 5 bpm, P <.0001 in the warm‐humid environment) and decrease of %weight change was different in hot‐dry environment (1.59 ± 0.12% and 1.25 ± 0.05%, P =.0039), but not in the warm‐humid environment. Conclusions: Wearing a FAJ may mitigate heat strain both in hot or humid environments. [ABSTRACT FROM AUTHOR]

Heat illnesses are critical for endurance athletes living in tropical and developing countries. However, the requirements of these athletes have not been considered in existing sportswear. Therefore, this study aims to assess the perceptions of endurance athletes living in a developing and tropical country regarding cooling sportswear. Four focus groups were conducted with 20 Sri Lankan endurance cycling athletes. Participants desired cooling sportswear to dissipate heat effectively in a tropical climate and to support personalized cooling while blocking heat discomfort from external sunlight. They preferred uniformity and team representation in the cooling sportswear design, expressing their emotional expectations related to the culture. Furthermore, participants recommended utilizing local resources for producing high-performance cycling wear to cost-effectively fulfil their requirements. The climatic, cultural and economic factors identified in this study shed light onto sportswear design for athletes living in tropical and developing countries. [ABSTRACT FROM AUTHOR]

This study investigated the effects of cooling between exercise bouts and post-exercise with a commercially available fan cooling jacket on thermal and perceptual responses during and following exercise in hot-humid environments. Ten male athletes completed two 30 min cycling bouts at a constant workload (1.4 watts⋅kg–1 of body mass) with a 5 min recovery period in between. Exercise was followed by a 10 min recovery period. In an environmental chamber (33°C, 65% relative humidity), participants performed two trials with (FCJ) or without (CON) the fan cooling jacket on a T-shirt during the 5 min inter-exercise and 10 min post-exercise recovery periods. Mean, chest and upper arm skin temperatures, and thermal sensation and comfort were lower in FCJ than CON trial during and following exercise (P < 0.05). Thigh and calf skin temperatures, infrared tympanic temperature and heart rate were lower in FCJ than CON trial during the experimental trials (P < 0.05). The rates of fall in mean, chest and upper arm skin temperatures, infrared tympanic temperature and thermal sensation and comfort were faster in FCJ than CON trial during both recovery periods (P < 0.05). There were faster rates of fall in thigh and calf skin temperatures and heart rate in FCJ than CON trial during the post-exercise recovery period (P < 0.05). No difference was observed between trials in the rating of perceived exertion (P > 0.05). This study indicates that cooling between exercise bouts and post-exercise with the fan cooling jacket would effectively mitigate thermal strain and perception/discomfort during and following exercise in hot-humid environments. This garment would reduce whole-body skin temperature quickly while promoting falls in lower-body as well as upper-body skin temperatures.

This study investigated the effects of cooling between exercise bouts and post-exercise with a commercially available fan cooling jacket on thermal and perceptual responses during and following exercise in hot-humid environments. Ten male athletes completed two 30 min cycling bouts at a constant workload (1.4 watts⋅kg–1 of body mass) with a 5 min recovery period in between. Exercise was followed by a 10 min recovery period. In an environmental chamber (33°C, 65% relative humidity), participants performed two trials with (FCJ) or without (CON) the fan cooling jacket on a T-shirt during the 5 min inter-exercise and 10 min post-exercise recovery periods. Mean, chest and upper arm skin temperatures, and thermal sensation and comfort were lower in FCJ than CON trial during and following exercise (P < 0.05). Thigh and calf skin temperatures, infrared tympanic temperature and heart rate were lower in FCJ than CON trial during the experimental trials (P < 0.05). The rates of fall in mean, chest and upper arm skin temperatures, infrared tympanic temperature and thermal sensation and comfort were faster in FCJ than CON trial during both recovery periods (P < 0.05). There were faster rates of fall in thigh and calf skin temperatures and heart rate in FCJ than CON trial during the post-exercise recovery period (P < 0.05). No difference was observed between trials in the rating of perceived exertion (P > 0.05). This study indicates that cooling between exercise bouts and post-exercise with the fan cooling jacket would effectively mitigate thermal strain and perception/discomfort during and following exercise in hot-humid environments. This garment would reduce whole-body skin temperature quickly while promoting falls in lower-body as well as upper-body skin temperatures. [ABSTRACT FROM AUTHOR]

Construction workers are at high risk of heat-related illnesses during summer months in India. The personal cooling garment (PCG) is a microclimate assistive device that provides protection from heat stress. The applicability and efficacy of wearing PCG for the physiological and subjective responses were tested on 29 healthy construction workers at actual field worksites. During the test, the climatic conditions were 103.64 ± 38.3°F dry bulb temperature, 41.2 ± 13.4% relative humidity, and wet bulb globe temperature 91.43 ± 39.92°F. Mean weighted skin temperature was significantly lowered by 38.66 ± 33.98°F when wearing PCG as compared with wearing habitual clothing (HC), 32.36 ± 33.44°F (p < .05). Mean sweat loss was also significantly lower when wearing PCG: 0.365 ± 0.257 kg as compared with wearing HC: 0.658 ± 0.342 kg (p < .05). Heart rate, along with back and chest skin temperatures were significantly reduced with wearing PCG. The present study suggests that PCG provides an affordable way of alleviating the discomfort and physiological strain caused by environmental heat exposure. [ABSTRACT FROM AUTHOR]

We investigated the effects of mild evaporative cooling applied to the torso, before or during running in the heat. Nine male participants performed three trials: control-no cooling ( CTR), pre-exercise cooling ( PRE-COOL), and during-exercise cooling ( COOL). Trials consisted of 10-min neutral exposure and 50-min heat exposure (30 °C; 44% humidity), during which a 30-min running protocol (70% VO2max) was performed. An evaporative cooling t-shirt was worn before the heat exposure ( PRE-COOL) or 15 min after the exercise was started ( COOL). PRE-COOL significantly lowered local skin temperature ( Tsk) (up to −5.3 ± 0.3 °C) ( P < 0.001), mean Tsk (up to −2 ± 0.1 °C) ( P < 0.001), sweat losses (−143 ± 40 g) ( P = 0.002), and improved thermal comfort ( P = 0.001). COOL suddenly lowered local Tsk (up to −3.8 ± 0.2 °C) ( P < 0.001), mean Tsk (up to −1 ± 0.1 °C) ( P < 0.001), heart rate (up to −11 ± 2 bpm) ( P = 0.03), perceived exertion ( P = 0.001), and improved thermal comfort ( P = 0.001). We conclude that the mild evaporative cooling provided significant thermoregulatory benefits during exercise in the heat. However, the timing of application was critical in inducing different thermoregulatory responses. These findings provide novel insights on the thermoregulatory role of Tsk during exercise in the heat. [ABSTRACT FROM AUTHOR]