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Artykuły w czasopismach na temat "Sweat Evaporation"
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Guan, Manhao, Simon Annaheim, Martin Camenzind, Jun Li, Sumit Mandal, Agnes Psikuta i René Michel Rossi. "Moisture transfer of the clothing–human body system during continuous sweating under radiant heat". Textile Research Journal 89, nr 21-22 (19.03.2019): 4537–53. http://dx.doi.org/10.1177/0040517519835767.
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Mass transfer due to perspired moisture in a clothing system is critical for the understanding of thermo-physiology and thermal protection of a clothed body. Previous studies usually investigated moisture transfer without considering the effect of liquid sweating or external heat hazards. To understand the mechanisms of sweat evaporation, accumulation and dripping with continuous sweating under radiant heat, a multi-phase experiment was designed with a sweating Torso. The concept of clothed wettedness was proposed to understand sweat evaporation of the clothed body. Results showed that the evaporation rate of the clothed body increased with increasing perspiration rate and the rate increase can be explained by the material properties (e.g., material composition, hydrophilicity and evaporative resistance ([Formula: see text])), which affected the sweat accumulation ability. Results also demonstrated a dual relationship of [Formula: see text] with the evaporation rate of the clothed body. Firstly, the evaporation rate was increased for greater [Formula: see text] due to the higher moisture accumulation. Secondly, when [Formula: see text] exceeded a certain value, the evaporation rate decreased with greater [Formula: see text] due to the reduction in the mass transfer coefficient. For radiant heat exposure, evaporated sweat may condense on the skin surface, decreasing the evaporation rate and increasing the dripping rate. The sweat transfer process was also investigated in detail by the combined analysis of the sweat transfer rate and the evaporative cooling efficiency. This study provides insights into how continuous liquid sweat transfers and evaporates in the clothed body and its interaction with clothing material and environment radiant heat, contributing to the understanding of thermo-physiological burden and thermal protection of the clothed body with intensive activities.
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Shrestha, Dev Chandra, Saraswati Acharya i Dil Bahadur Gurung. "A Finite Element Approach to Evaluate Thermoregulation in the Human Body due to the Effects of Sweat Evaporation during Cooking, Cleaning, and Walking". Mathematical Problems in Engineering 2021 (26.05.2021): 1–14. http://dx.doi.org/10.1155/2021/5539151.
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Sweat evaporation is the principal process of dissipating heat energy in a hot environment and during activities. Sweat loss is significantly affected by the level of energy expenditure, hormones, and the number of sweat glands. The thickness of the skin layer plays a vital role to maintain body temperature. The rate of sweat evaporation varies with ambient temperature and activity level. On increasing both metabolism and ambient temperature, sweat rate loss also increases and controls the body in the thermoregulatory system. The evaporative sweat release rate has a linear behavior. The appropriate physical and physiological parameters that affect thermoregulation have been incorporated into the model. The study presents the temperature distribution in three layers: epidermis, dermis, and subcutaneous tissue (SST) of the human dermal parts during cooking, cleaning, and walking. The solution is obtained by using the finite element method. The results demonstrate that the body mechanism keeps the body in thermoregulation by increasing the sweat evaporation rate exhibited by increasing the ambient temperature and metabolism during strenuous activities.
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Cramer, Matthew N., i Ollie Jay. "Compensatory hyperhidrosis following thoracic sympathectomy: a biophysical rationale". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 302, nr 3 (1.02.2012): R352—R356. http://dx.doi.org/10.1152/ajpregu.00419.2011.
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A side-effect of endoscopic thoracic sympathectomy (ETS) is compensatory hyperhidrosis (CH), characterized by excessive sweating from skin areas with intact sudomotor function. The physiological mechanism of CH is unknown, but may represent an augmented local sweat rate from skin areas with uninterrupted sympathetic innervation based on evaporative heat balance requirements. For a given combination of activity and climate, the same absolute amount of evaporation (if any) is needed to balance the rate of metabolic heat production both pre- and post-ETS. However, the rate of local sweating per unit of skin surface area with intact sudomotor activity must be greater post-ETS as evaporation must be derived from a smaller skin surface area. Under conditions with high evaporative requirements, greater degradations in sweating efficiency associated with an increased dripping of sweat should also occur post-ETS, further pronouncing the sweat rate required for heat balance. In conclusion, in addition to the potential role of psychological stimuli for increased sudomotor activity, the existence of CH post-ETS can be described by the interplay between fundamental thermoregulatory physiology and altered heat balance biophysics and does not require a postoperative alteration in physiological control.
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Chen, Xiao-Ming, Yong-Jiang Li, Dan Han, Hui-Chao Zhu, Chun-Dong Xue, Hsiang-Chen Chui, Tun Cao i Kai-Rong Qin. "A Capillary-Evaporation Micropump for Real-Time Sweat Rate Monitoring with an Electrochemical Sensor". Micromachines 10, nr 7 (7.07.2019): 457. http://dx.doi.org/10.3390/mi10070457.
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Sweat collection and real time monitoring of sweat rate play essential roles in physiology monitoring and assessment of an athlete’s performance during exercise. In this paper, we report a micropump for sweat simulant collection based on the capillary–evaporation effect. An electrochemical sensor is integrated into the micropump, which monitors the flow rate in real-time by detecting the current using three electrodes. The evaporation rate from micropore array, equivalent to the sweat rate, was theoretically and numerically investigated. The designed micropump yields the maximum collection rate as high as 0.235 μ L/min. In addition, the collection capability of the micropump was validated experimentally; the flow rate through the microchannel was further detected in real-time with the electrochemical sensor. The experimental maximum collection rate showed good consistency with the theoretical data. Our proposed device shows the potential for sweat collection and real-time monitoring of sweat rate, which is a promising candidate for being a wearable platform for real-time physiology and performance monitoring during exercise.
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Otomasu, Kinuyo, Masaki Yamauchi, Nobu Ohwatari, Takaaki Matsumoto, Katsuhiko Tsuchiya i Mitsuo Kosaka. "Analysis of sweat evaporation from clothing materials by the ventilated sweat capsule method". European Journal of Applied Physiology 76, nr 1 (1.06.1997): 1–7. http://dx.doi.org/10.1007/s004210050205.
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Lolla, Venkata Yashasvi, Pranav Shukla, Stevan D. Jones i Jonathan B. Boreyko. "Evaporation-Induced Clogging of an Artificial Sweat Duct". ACS Applied Materials & Interfaces 12, nr 47 (16.11.2020): 53403–8. http://dx.doi.org/10.1021/acsami.0c13493.
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Shimazaki, Yasuhiro, i Shunpei Katsuta. "Spatiotemporal sweat evaporation and evaporative cooling in thermal environments determined from wearable sensors". Applied Thermal Engineering 163 (grudzień 2019): 114422. http://dx.doi.org/10.1016/j.applthermaleng.2019.114422.
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Zhao, Mengmeng, Chuansi Gao, Faming Wang, Kalev Kuklane, Ingvar Holmér i Jun Li. "The torso cooling of vests incorporated with phase change materials: a sweat evaporation perspective". Textile Research Journal 83, nr 4 (27.09.2012): 418–25. http://dx.doi.org/10.1177/0040517512460294.
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Cooling vests incorporated with phase change materials (PCMs) add extra insulation and restrict sweat evaporation. It is still unclear how much cooling benefit they can provide. The aim of this study was to investigate the torso cooling of the PCM vests in two hot environments: hot humid (HH, 34°C, 75% relative humidity (RH)) and hot dry (HD, 34°C, 37% RH). A pre-wetted torso fabric skin was used to simulate torso sweating on a thermal manikin. Three cooling vests incorporated with three melting temperatures ( Tm) of PCMs were tested ( Tm = 21°C, Tm = 24°C and Tm = 28°C). They were worn under a military ensemble (total thermal insulation 1.60 clo; evaporative resistance 0.0516 kPaċm2/W), respectively. In a HH environment all the three cooling vests provided effective torso cooling; in a HD environment the cooling benefit was negative. In both environmental conditions, the evaporative cooling was greatly restricted by the cooling vests. The study indicated that when wearing the protective clothing with the relatively low evaporative resistance and when sweat production was high, the cooling vests were effective in a HH environment, but not in a HD environment.
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Bariya, Mallika, Lu Li, Rahul Ghattamaneni, Christine Heera Ahn, Hnin Yin Yin Nyein, Li-Chia Tai i Ali Javey. "Glove-based sensors for multimodal monitoring of natural sweat". Science Advances 6, nr 35 (sierpień 2020): eabb8308. http://dx.doi.org/10.1126/sciadv.abb8308.
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Sweat sensors targeting exercise or chemically induced sweat have shown promise for noninvasive health monitoring. Natural thermoregulatory sweat is an attractive alternative as it can be accessed during routine and sedentary activity without impeding user lifestyles and potentially preserves correlations between sweat and blood biomarkers. We present simple glove-based sensors to accumulate natural sweat with minimal evaporation, capitalizing on high sweat gland densities to collect hundreds of microliters in just 30 min without active sweat stimulation. Sensing electrodes are patterned on nitrile gloves and finger cots for in situ detection of diverse biomarkers, including electrolytes and xenobiotics, and multiple gloves or cots are worn in sequence to track overarching analyte dynamics. Direct integration of sensors into gloves represents a simple and low-overhead scheme for natural sweat analysis, enabling sweat-based physiological monitoring to become practical and routine without requiring highly complex or miniaturized components for analyte collection and signal transduction.
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Hsing, Wen Hao, Wei Jay Yang i Ya Lan Hsing. "Far-Infrared Emission of Filled Fabric by Sweat". Advanced Materials Research 287-290 (lipiec 2011): 2610–13. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.2610.
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In this experiment, use of far infrared filled fabric of instillation of sweat on the man the purpose of detecting artificial sweat on the far-infrared radiation rate of fiber influence and change the fiber type, weight, the proportion of artificial sweat to detect far-infrared radiation rate of thick fabrics change. The results showed that the infrared fiber’s radiation rate of cotton fiber to be higher about 0.07. Far-infrared on a thick layer of fabric at the instillation of 3% weight, 6% of the weight, 9% of the weight of artificial sweat, its far-infrared radiation rate would be the relationship between the rapid decline due to sweat, but with the artificial sweat evaporation, radiation will slow the rate of rise, Another far-infrared fiber samples of 3g weights repeated titration sweat, the far-infrared fiber samples of the far-infrared radiation rate will be increased about 0.005 ~ 0.007
Rozprawy doktorskie na temat "Sweat Evaporation"
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Chen, Xi. "Climate and landscape controls on seasonal water balance at the watershed scale". Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6263.
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The main goal of this dissertation is to develop a seasonal water balance model for evaporation, runoff and water storage change based on observations from a large number of watersheds, and further to obtain a comprehensive understanding on the dominant physical controls on intra-annual water balance. Meanwhile, the method for estimating evaporation and water storage based on recession analysis is improved by quantifying the seasonal pattern of the partial contributing area and contributing storage to base flow during low flow seasons.
A new method for quantifying seasonality is developed in this research. The difference between precipitation and soil water storage change, defined as effective precipitation, is considered as the available water. As an analog to climate aridity index, the ratio between monthly potential evaporation and effective precipitation is defined as a monthly aridity index. Water-limited or energy-limited months are defined based on the threshold of 1. Water-limited or energy-limited seasons are defined by aggregating water-limited or energy-limited months, respectively.
Seasonal evaporation is modeled by extending the Budyko hypothesis, which is originally for mean annual water balance; while seasonal surface runoff and base flow are modeled by generalizing the proportionality hypothesis originating from the SCS curve number model for surface runoff at the event scale. The developed seasonal evaporation and runoff models are evaluated based on watersheds across the United States. For the extended Budyko model, 250 out of 277 study watersheds have a Nash-Sutcliff efficiency (NSE) higher than 0.5, and for the seasonal runoff model, 179 out of 203 study watersheds have a NSE higher than 0.5.
Furthermore, the connection between the seasonal parameters of the developed model and a variety of physical factors in the study watersheds is investigated. For the extended Budyko model, vegetation is identified as an important physical factor that related to the seasonal model parameters. However, the relationship is only strong in water-limited seasons, due to the seasonality of the vegetation coverage. In the seasonal runoff model, the key controlling factors for wetting capacity and initial wetting are soil hydraulic conductivity and maximum rainfall intensity respectively. As for initial evaporation, vegetation is identified as the strongest controlling factor. Besides long-term climate, this research identifies the key controlling factors on seasonal water balance: the effects of soil water storage, vegetation, soil hydraulic conductivity, and storminess.
The developed model is applied to the Chipola River watershed and the Apalachicola River basin in Florida for assessing potential climate change impact on the seasonal water balance. The developed model performance is compared with a physically-based distributed hydrologic model of the Soil Water Assessment Tool, showing a good performance for seasonal runoff, evaporation and storage change.Ph.D.
Doctorate
Civil, Environmental and Construction Engineering
Engineering and Computer Science
Environmental Engineering
Książki na temat "Sweat Evaporation"
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Falk, Bareket, i Raffy Dotan. Temperature regulation. Redaktorzy Neil Armstrong i Willem van Mechelen. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198757672.003.0014.
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Under all but the most extreme environmental heat conditions, children control their body temperature (at rest and during exercise) as well as adults. Children, however, use a different thermoregulatory strategy. Compared with adults, children rely more on dry heat dissipation and less on evaporative cooling (sweating). Their larger skin surface-area relative to mass does put children at increasing disadvantage, relative to adults, as ambient temperatures rise above skin temperature. Similarly, they become increasingly disadvantaged upon exposure to decreasing temperatures below the thermo-neutral zone. Like adults, children inadvertently dehydrate while exercising in hot conditions and are often hypohydrated, even before exercise, and their core temperature rises considerably more than adults in response to a given fluid (sweat) loss, which may put them at higher risk for heat-related injury. However, epidemiological data show rates of both heat- and cold-related injuries among children and adolescents as similar or lower than at any other age.
Części książek na temat "Sweat Evaporation"
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Omer, Altyeb Ali Abaker, Ming Li, Xin-liang Liu, Wen-jun Liu, Yang Liu, Yasir M. F. Mukhtar, Jan Ingenhoff i Wen Liu. "The Effect of the Novel Agricultural Photovoltaic System on Water Evaporation Reduction and Sweet Potato Yield". W Proceedings of the 2022 International Petroleum and Petrochemical Technology Conference, 567–78. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2649-7_50.
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Nielsen, Ruth. "EVAPORATION OF SWEAT FROM DRESSED MAN". W Advances In Industrial Ergonomics And Safety V, 429–34. CRC Press, 1993. http://dx.doi.org/10.1201/9781482272413-60.
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Mitchell, Graham. "Keeping Cool". W How Giraffes Work, 316–41. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197571194.003.0014.
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Measurement of giraffe body temperature has shown that it is ~38.5oC but it can vary by ~5oC over the course of a day. Body heat is derived from fermentation of browse, other metabolic processes and radiant heat. Heat loss mechanisms partly depend on body surface area. Despite their unusual shape the body surface area of giraffes is similar to that in other equivalent body mass mammals: a shorter trunk is offset by a longer neck and legs. Heat loss by radiation is constant, by conduction rare and minimal. Their long, slender legs and neck are an advantage for convective and evaporative heat loss from the skin: heat transfer is inversely proportional to the square root of diameter. Evaporation from the respiratory system occurs through the nasal mucosa, the surface area of which in giraffes is large. Cooling of the nasal mucosa and blood follows and cool blood drains in to the jugular vein and contributes to whole body cooling and cooling of the blood supplying the brain by heat exchange in the carotid rete. Similar heat exchange may occur across the surface of the ossicones. Behavior changes when ambient temperature exceeds skin temperature. Giraffes re-orientate their bodies to minimize radiant heat gain and seek shade. A unique arrangement of blood vessels supplying blood to skin patches allows patches to act as thermal windows through which heat can be lost an arrangement enhanced by evaporation: sweat gland density in the skin of patches is greater than it is elsewhere.
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Mitchell, Graham. "Water Balance in Giraffes". W How Giraffes Work, 241–60. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197571194.003.0011.
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Wild giraffes live in arid environments. Having access to water and minimizing water requirements are critical. The main sources of water are the water in browse and water generated by metabolism. Giraffes rely less on surface water: intermittent use of surface water is a legendary characteristic of giraffes. The volume of water needed depends on body mass. For a giraffe weighing 750 kg, ~25 L of water is needed daily. The water content of browse is ~60%, and as a giraffe of that mass will eat ~35 kg of fresh browse daily, it simultaneously will acquire ~20 L of water. Metabolism of the fat, carbohydrates, and proteins in 35 kg of fresh browse will produce ~10 L of water. These two sources of water exceed daily requirements and reduce the need to drink surface water. Water is lost through feces, evaporation from the skin and respiratory tract, and in urine. Fecal water loss and water lost in exhaled air amount to ~4 L daily (~2 L each). It is not known if giraffes sweat, but their skin contains active sweat glands. The volume of water lost as sweat will vary according to what thermoregulatory mechanisms are activated to minimize sweating, but may be 5 L daily. Obligatory excretion of water-soluble wastes in urine can account for most water lost daily, and that amount is related to kidney anatomy and function. In a 750-kg giraffe, obligatory urine volume is ~10 L daily.
Streszczenia konferencji na temat "Sweat Evaporation"
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Zhang, Xinsheng, Ming Zhou, Zhi Huang, Xiaoding Xu, Xianzheng Zhang i Xuejiao Hu. "Biomimetic Passive Skin Cooling for High-End Handheld Devices". W ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18370.
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Increasing functionality demands more heat dissipation from the skin of handheld microelectronics devices. The maximum amount of heat that can be dissipated passively, prescribed by the natural convection and blackbody radiation theories, is becoming the bottleneck. In this paper, we propose a novel technique that may overcome this passive cooling limit. It is made possible by using a biomimetic skin capable of perspiration on demand. The key component of the biomimetic skin is a thin layer of temperature sensitive hydro gel (TSHG). The TSHG layer can sweat the skin with moisture when the skin temperature is higher than the TSHG’s lower critical solution temperature (LCST), and thus boost the heat dissipation rate through evaporation. The TSHG layer can be refilled by absorbing the moisture in air when the device batteries are being recharged. A generic practice of this novel cooling technique with preliminary analysis and experimental results is presented. With this novel passive cooling technology, a handheld device can be powered 2–4.8 times higher, and may be powerful enough to run a desktop operation system like a personal computer.
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Kerwin, Michael, Christopher Bascomb i John Culver. "Infantry Soldier Cooling". W ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70086.
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This report discusses the design problem of developing an air-based cooling system for an infantry soldier. The background explores the different designs that already exist as well as specific parts and materials that will be essential to the design process. Currently, liquid-based cooling systems are the most explored types of cooling devices. However, there are specific downsides to this type of cooling device. As opposed to an air-based system, water requires more energy to be cooled, and therefore more battery power. The liquid-based system is also relatively bulky and heavy due to battery size and the water that runs through the system. With air-based cooling systems, efficient cooling is possible. An air-based cooling system was tested in a laboratory and field environment. In a humid environment, a desiccant attachment can improve the cooling device’s effectiveness. The cooling design effectively reduces the wearer’s core body temperature through evaporative cooling. The design evaporates a significant amount of sweat from wearer’s back and torso. While the prototype can be improved, evaporative cooling is an effective cooling solution for Soldiers.
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Singh, Vikram, Erik Svensson, Sebastian Verhelst i Martin Tuner. "Investigating the Potential of an Integrated Coolant Waste Heat Recovery System in an HD Engine Using PPC Operation". W ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9708.
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With the increasing focus on reducing emissions and making fuel efficient vehicles within the automotive industry over the past few years, new methods are constantly being investigated to improve the efficiency of the powertrain. One such method is recovering waste heat from the exhaust gases as well as the coolant using a thermodynamic cycle such as a Rankine cycle. However, most studies looking into low temperature or coolant heat recovery investigate the use of a separate secondary cycle for the recovery of waste heat itself. This has the disadvantage of having the working fluid at a lower temperature than the coolant which reduces the recovery efficiency. This paper investigates the potential of an integrated Rankine cycle waste heat recovery system where the coolant also acts as the refrigerant and is integrated with the exhaust gas recirculation waste heat recovery. The refrigerant/coolant used for this study is ethanol, while being used in two modes for low temperature/coolant recovery: using the engine as the preheater and using it as an evaporator. Using a combination of GT Power and Matlab, a Scania D13 engine was simulated in partially premixed combustion operation with a waste heat recovery system. For the engine load-speed range, the coolant flow rate, pressure ratio and superheat were swept for determining the optimal values for maximizing output power. It was seen that while using the engine both as a preheater and as an evaporator the recoverable power increased in comparison to using only the exhaust gas recirculation heat for recovery. When using the engine for preheating, the recoverable power increased marginally with an indicated efficiency gain of less than 0.5 percentage points whereas when using the engine for the evaporation of the coolant, the indicated efficiency showed gains of up to 1.7 percentage points in comparison to using EGR-only heat recovery with a total gain in indicated efficiency of up to 5.5 percentage points. This larger gain in recoverable power while using the engine as an evaporator in comparison to as a preheater is due to the location of the pinch point in analyzing the heat exchange process. The system behavior was also studied with regards to the pressure ratio, the mass flow rate of coolant and the superheat. It was generally observed that at higher loads and speeds these parameters increased as more waste heat was available for recovery for the system.
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Sharma, A., S. K. S. Boetcher, W. A. Aissa i M. J. Traum. "Impact of Interstitial Mass Transport Resistance on Water Vapor Diffusion Through Southern Mills Defender™ 750 Fabric Layers". W ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44485.
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Textiles maintain wearer comfort by allowing evaporated sweat to permeate through, providing thermal management and keeping skin dry. Each textile layer presents a resistance to mass transport consistent with its physical structure (i.e., thickness, porosity, and tortuosity). However, when textiles are layered, water vapor transport becomes more complex because diffusing molecules must traverse interstitial spaces between layers. Interstitial mass transport resistances of significant magnitude can reduce rates of water vapor transport through layered textile stacks. The prevailing textile mass transport resistance interrogation method is ASTM F1868: “Standard Test Method for Thermal and Evaporative Resistance of Clothing Materials Using a Sweating Hot Plate.” A self-calibrating element of this method is to measure one, two, three, and four fabric layers. Each newly added layer is prescribed to increase the stack mass transport resistance by the integer resistance presented by a single layer with no interstitial resistance consideration. Four improvements to ASTM F1868 are recommended: 1) gravimetric mass transport measurement, 2) a Stefan flow model, 3) correct accounting for apparatus mass transport resistances, and 4) recognizing and measuring interstitial mass transport resistances. These improvements were implemented and evaluated by running tests using Southern Mills Defender™ 750 fabric, the calibration standard used for ASTM F1868, on a new gravimetric experimental apparatus. The mass transport resistance of one fabric layer measured via the gravimetric method is related to the ASTM F1868 value through working fluid properties. Using the gravimetric approach, mass transport resistance for a single layer of calibration fabric was measured at 60.3 ± 14.4 s/m, which is consistent with the prescribed result from ASTM F1868 (after the conversion factor), 73.1 ± 7.3 s/m. The diffusion coefficient for water vapor in air in the fabric pores measured by gravimetric experiment, (2.02 ± 0.59) × 10−5 m2/s, agrees (within experimental uncertainty) with the theoretical value for the experimental conditions, 2.54 × 10−5 m2/s. However, for stacks of two or more calibration fabric layers, the gravimetric approach does not agree with the prescribed ASTM F1868 result due to interstitial mass transport resistance between fabric layers. The measured interstitial resistance value is 23.6 s/m, 39.1% of a single fabric layer, a value too significant to be ignored in engineering analysis.
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Carballo Leyenda, Belén, Jorge Gutiérrez Arroyo, José Gerardo Villa Vicente, Fabio García-Heras, Juan Rodríguez Medina i Jose A Rodríguez-Marroyo. "Laboratory assessment of heat strain in female and male wildland firefighters". W 14th International Conference on Applied Human Factors and Ergonomics (AHFE 2023). AHFE International, 2023. http://dx.doi.org/10.54941/ahfe1003976.
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Wildland firefighters (WFF) face a set of specific work-related factors that directly affect their physical and cognitive abilities and compromise their health and safety. The working conditions include hard physical work and environmental conditions that combine high temperatures and high radiant heat. Such environments make using personal protective equipment (PPE) mandatory to protect them from risks. This fact restricts heat removal and adds extra weight, increasing thermal strain and the risk of heat-related illnesses on WFF. Since the number of females WFF has increased, it is necessary to study the repercussions of heat stress on this group. To date, it is not yet well-known whether sex-related differences in thermoregulation will be relevant when the individuals are wearing PPE and performing high physical effort in a hot environment. Therefore, we aimed to investigate the physiological response when performing moderate to high-intensity effort in a hot-dry environment while wearing PPE according to sex. Twenty WFF 10 females [23.9 ± 3.2 yr, 163.8 ± 3.4 cm and 62.7 ± 9.1 kg] and 10 males [31.9 ± 6.6 yr, 178.8 ± 5.8 cm and 73.9 ± 7.7 kg]) performed a 125 min treadmill test in a controlled ambient (30 ºC and 30% relative humidity). The protocol consisted of two exercise stages where WFF performed different continuous and variable exercise bouts in order to mimic the effort performed during real deployments. Participants wore the full standard PPE during the test. Oxygen uptake (VO2), heart rate (HR), core temperature (CT) and chest temperature (SkT) were monitored throughout the test. HR and CT were used to calculate the physiological strain index (PSI). Differences in body mass pre-post trials corrected for fluid intake were used to calculate sweat production (SwP), sweating rate (SwR), and evaporative efficiency (EE). Differences (p < 0.05) between females and males were found in %VO2max (62.5 ± 7.4 vs 55.3 ± 5.), HR (155 ± 10 vs 134 ± 14 beats·min–1), % of maximal HR (81.3 ± 3.5 vs 42.3 ± 6.5), CT (38.0 ± 10 vs 37.7 ± 0.33 ºC), SkT (36.0 ± 0.6 vs 35.3 ± 0.6 ºC) and PSI (4.1 ± 0.5 vs 3.5 ± 0.6). Even though SwR was higher (p < 0.05) for male participants (1001.5 ± 268.3 ml) compared to females (647.5 ± 145.9 ml), females had higher EE (32.9 ± 4.6 vs 16.7 ± 6.2 %). In conclusion, performing high-intensity exercise in hot-dry conditions while wearing PPE leads to a higher thermal and cardiovascular load for female WFF, making them more susceptible to heat illness. These results could be linked to lower aerobic fitness, sweating rate, and hormonal aspects that increased the thermal burden.
Raporty organizacyjne na temat "Sweat Evaporation"
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Fuchs, Marcel, Ishaiah Segal, Ehude Dayan i K. Jordan. Improving Greenhouse Microclimate Control with the Help of Plant Temperature Measurements. United States Department of Agriculture, maj 1995. http://dx.doi.org/10.32747/1995.7604930.bard.
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A model of the energy balance of a transpiring crop in a greenhouse was developed in a format suitable for use in climate control algorithms aimed at dissipating excess heat during the warm periods. The model's parameters use external climatic variables as input. It incorporates radiation and convective transfer functions related to the operation of control devices like shading screens, vents, fans and enhanced evaporative cooling devices. The model identified the leaf boundary-layer resistance and the leaf stomatal and cuticular resistance as critical parameters regulating the temperature of the foliage. Special experiments evaluated these variables and established their relation to environmental factors. The research established that for heat load conditions in Mediterranean and arid climates transpiring crops maintained their foliage temperature within the range allowing high productivity. Results specify that a water supply ensuring minimum leaf resistance to remain below 100 s m-1, and a ventilation rate of 30 air exchanges per hour, are the conditions needed to achieve self cooling. Two vegetable crops, tomato and sweet pepper fulfilled maintained their leaf resistance within the prescribed range at maturity, i.e., during the critical warm season. The research evaluates the effects of additional cooling obtained from wet pad systems and spray wetting of foliage.