Impact of electrical heating on effective thermal Insulation of a multi-layered winter clothing system for optimal heating efficiency

2016 ◽  
Vol 28 (2) ◽  
Author(s):  
Huiju Park ◽  
Soo-kyung Hwang ◽  
Joo-Young Lee ◽  
Jintu Fan ◽  
Youngjin Jeong
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Electric Heating ◽  
The Body ◽  
Electrical Heating ◽  
Thermal Manikin ◽  
Heating Unit ◽  
Heating Efficiency ◽  
Body Heat

Purpose This paper investigated the impact of the distance of the heating unit from the body in a multi-layered winter clothing system on effective thermal insulation and heating efficiency. Design/methodology/approach To identify changes in the thermal insulation and heating efficiency of electrical heating in different layers inside a winter clothing ensemble, a series of thermal manikin tests was conducted. A multi-layered winter ensemble with and without activation of a heating unit was tested on the thermal manikin under two different ambient temperature conditions (10°C and -5°C). Findings Results show that the effective thermal insulation of test ensembles increased by 5-7% with the activation of the heating unit compared to that without the activation. The closer the heating unit to the body, the higher the effective thermal insulation was in both ambient temperature conditions. This trend was more significant at lower ambient temperature. Research limitations/implications The results of this study indicate that providing electric heating next to the skin is the most effective in increasing effective thermal insulation and decreasing body heat loss in both ambient temperature (-5°C and 10°C). This trend was more remarkable in colder environment at -5°C of ambient temperature as evidenced by sharp decrease in heating efficiency and effective thermal insulation with an increase in distance between the manikin skin and heating unit at -5°C of ambient temperature compared to at 10°C of ambient temperature. Practical implications Based on the results, it is expected that proximity heating next to the skin, in cold environment, may reduce the weight and size of the battery for the heating unit because of the higher efficiency of electric heating and the potentially immediate perception of warmth supported by the greatest increase in effective thermal insulation, as well as the lowest heat loss that comes with activation of heating on the first layer in cold environment. Originality/value The finding of this study provides guidelines to sportswear designers, textile scientists, sports enthusiasts, and civilians who consider electric heating benefits for improved thermal comfort and safety in cold environments, especially in the areas of outdoor and winter sports and in military service. The results of this study indicate that providing electric heating next to the skin is the most effective in increasing effective thermal insulation and decreasing body heat loss in both ambient temperature (-5°C and 10°C).

Effects of Clothing Ventilative Designs on Thermal Insulation under Varying Wind Conditions

2011 ◽  
Vol 332-334 ◽  
pp. 1927-1930 ◽  
Author(s):  
Xiang Hui Zhang ◽  
Jun Li
Keyword(s):  
Experimental Investigation ◽  
Thermal Comfort ◽  
Thermal Insulation ◽  
The Body ◽  
Thermal Manikin ◽  
Clothing Insulation ◽  
Vertical Side ◽  
Wind Velocities ◽  
Heat And Moisture ◽  
Body Heat

This paper reports on an experimental investigation of the effects of clothing ventilative designs on thermal comfort measured in terms of thermal insulation. Eight T-shirts with varying areas and locations of mesh fabric were designed and produced for testing on a dry thermal manikin. Clothing thermal insulation of T-shirts was measured under three wind velocities: 0.5, 1 and 2m/s. The results showed that, the areas and locations of ventilation panels affect the total thermal insulation. The T-shirts with larger area of mesh fabric are preferable in terms of releasing more body heat. Among various designs tested, mesh fabrics applied at two vertical side seams can most effectively release heat and moisture from the body. Clothing insulation is also greatly affected by wind.

Comparison of clothing thermal comfort properties measured on female and male sweating manikins

2016 ◽  
Vol 87 (18) ◽  
pp. 2214-2223 ◽  
Author(s):  
Chao Sun ◽  
Jintu Fan
Keyword(s):  
Thermal Comfort ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Female Body ◽  
Body Shape ◽  
The Body ◽  
Thermal Manikin ◽  
Unit Surface Area ◽  
Evaporative Resistance ◽  
Evaporative Water

Thermal manikins simulating human body’s thermal regulatory system are essential tools for understanding the heat exchange between human body and the environment and also for evaluating the thermal comfort of clothing and near environment. However, most existing thermal manikins adopt a male’s body shape and no sweating female thermal manikin has been reported so far. Furthermore, it is unclear how body shape (viz. male vs female) affects the heat loss and perspiration from the body. We report on a novel female sweating thermal manikin “Wenda”. Thermal properties of the nude body and clothing ensembles measured on “Wenda” are compared with those measured on the male manikin “Walter”. It was found that, although the more curvaceous female body reduces the thermal insulation of the nude manikin, it increases the apparent evaporative resistance at the same time. This may be due to the fact that the more curvaceous female body increases the surface still air layer to add resistance to heat loss by conduction and evaporative water loss by diffusion, and significantly increases the percentage of effective radiative area and the resultant radiative heat loss per unit surface area. It was further shown that clothing thermal insulation and apparent evaporative resistance measured on Wenda are typically 0 ∼ 11% higher than those measured on the male sweating fabric manikin-Walter, probably due to the greater clothing microclimate volume on the female manikin resulting from the looser fitting of the garments on the smaller female body and the more curvaceous surface of the female body.

scholarly journals INSTALLATION FOR DETERMINATION OF HEAT RELEASE OF HEATING RADIATORS

2021 ◽  
Vol 4 (164) ◽  
pp. 77-81
Author(s):  
Yu. Ivashina ◽  
V. Zavodyannyi
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Electrical Power ◽  
Electric Heating ◽  
Middle Part ◽  
Heat Losses ◽  
The Body ◽  
Heat Output ◽  
Stationary Mode

To calculate the share of thermal energy consumed by this apartment in an apartment building, it is necessary to determine the heat transfer of all heating radiators in the house. But the heat transfer given in the passport of the heating device corresponds to the temperature pressure equal to 70K. Often the owners install non-standard devices, so the problem of determining the heat transfer of heating radiators in real conditions is relevant. Thermometric method, which is called electric, is widely used for laboratory determination of heat transfer of heating devices. Water by means of the pump circulates through an electric copper and the investigated radiator. The heat output of the latter is defined as the difference between the supplied electrical power (boiler power plus pump) and heat loss. The purpose of the work is to develop and study the operation of the installation for determining the heat transfer of heating radiators, which had a simpler design and could ensure proper measurement accuracy. We have proposed a scheme and design of the installation for determining the heat transfer of electric heating radiators, which differs in that it does not include a circulating pump. Water in the system circulates under the action of gravity due to changes in the density of the coolant during heating and cooling. This greatly simplifies the circuit by eliminating not only the pump but also the valve and the air outlet valve. The heater chamber is made of a steel pipe with a diameter of 88 mm. A steel cover is attached to the lower flange, through which a 1-1.5 kW heater is introduced into the chamber. Two 1/2 ″ sections of pipe are welded to the body of the heater chamber, through which the radiator is connected by means of rubber couplings. The cylindrical surface of the chamber on top of the layer of internal insulation is covered with a shielding heater, the temperature of which is maintained equal to the surface temperature of the heater chamber in the middle part. A layer of external thermal insulation is installed on top of the shielding heater. To determine heat loss, the radiator is disconnected from the heater chamber, plugs are installed and insulated. In stationary mode, the dependence of the heater power on the temperature of the heater chamber is measured, which determines the power of heat losses. The simplification of the installation has led not only to its reduction in price, but also to an increase in accuracy due to the reduction of heat losses and the simplicity of their definition.

Tracking proficiency as a function of thermal balance

1959 ◽  
Vol 14 (3) ◽  
pp. 387-389 ◽  
Author(s):  
Robert B. Payne
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Visual Display ◽  
Thermal Balance ◽  
Statistical Analyses ◽  
Mathematical Function ◽  
Performance Decrement ◽  
Experimental Task ◽  
Extensive Training ◽  
Body Heat

An experiment was conducted for the purpose of learning a) whether or not performance decrement in monitoring and controlling a complex visual display is related to body heat loss and b) whether or not such an impairment can be forestalled by glycine administration. Following extensive training on the experimental task, 72 subjects were independently and randomly assigned to the 9 combinations of 3 ambient temperature conditions (70°, 55° and 40℉) and 3 glycine treatments (0, 20 and 40 gm), then required to execute a performance sequence lasting 3 hours and 20 minutes. Statistical analyses established that the mathematical function relating performance to temperature was a parabola having a maximum near 55°. No significant glycine effects were observed. Submitted on September 25, 1958

PROVIDING THERMAL COMFORT OF THE DISTAL SEGMENTS OF THE LOWER LIMBS BY USING AN AUTONOMOUS ELECTRIC HEATING SYSTEM

2021 ◽  
Author(s):  
I.S. Malakhova ◽  
◽  
T.K. Losik ◽  
O.V. Burmistrova
Keyword(s):  
Thermal Comfort ◽  
Thermal Insulation ◽  
Low Temperatures ◽  
Electric Heating ◽  
Heating System ◽  
The Body ◽  
Climatic Zone ◽  
Experimental Sample ◽  
Local Cooling ◽  
Additional Heat

Abstract. Introduction. Work in low temperatures can lead to both general and local cooling of the human body. Local cooling of the distal parts of the legs can limit the motor activity of the employee even with sufficient thermal insulation of the body general surface. Therefore, the use of an additional heat source in special shoes (autonomous electric heating system (AEHS)) can compensate heat losses in the distal parts of the legs and provide thermal comfort in conditions of low temperatures throughout the work. The purpose of the study: physiological and hygienic assessment of the additional heat sources (AEHS) influence on the thermal insulation of special shoes in conditions of low temperatures. Materials and methods. To assess the heat-protective properties of the special shoes experimental sample with an AEHS, a heat flux density and skin temperature meter ITP-MG 4.03/30 "POTOK" (LLC SKB Stroypribor, Chelyabinsk) was used. The presented sample was tested with the participation of 5 volunteers in three modes of autonomous electric heating in a microclimatic chamber for 60 minutes for each mode separately. The average air temperature in the chamber during the study was 2.5±0.5 °C. Based on the obtained data, the thermal insulation of special shoes with an AEHS was calculated. Results. The thermal insulation of the special shoes experimental sample without electric heating was 0.460±0.013 °C m2/W; and 0.512±0.01 and 0.549±0.01 °C m2/W using the minimum and medium electric heating modes-, respectively, which allows us to recommend the presented sample of special shoes with an autonomous electric heating system for work in a "Special" climatic zone when performing moderate-severity work. The thermal insulation of a special shoes sample with the maximum electric heating mode was 0.615±0.01 °C m2/W, which makes it possible to work with it in the IV climatic zone. Conclusions. The use of an AEHS increases the thermal insulation of special shoes, which provides sufficient protection for the distal parts of the legs, allows to expand the scope of its operation in strict compliance with the work and rest regime and can be a prevention of the occupational diseases development in workers at low temperatures.

Exertional fatigue and cold exposure: mechanisms of hiker's hypothermia

2007 ◽  
Vol 32 (4) ◽  
pp. 793-798 ◽  
Author(s):  
Andrew J. Young ◽  
John W. Castellani
Keyword(s):  
Heat Loss ◽  
Cold Exposure ◽  
Physiological Responses ◽  
Physical Exertion ◽  
The Body ◽  
Cold Weather ◽  
Behavioral Strategies ◽  
Peripheral Vasoconstriction ◽  
Vasoconstrictor Response ◽  
Body Heat

Participants in prolonged, physically demanding activities in cold weather are at risk of a condition known as “hiker's hypothermia”. During exposure to cold weather, the increased gradient favoring body heat loss to the environment must be balanced by physiological responses, clothing, and behavioral strategies that conserve body heat stores, or else body temperature will decline. The primary human physiological responses elicited by cold exposure are shivering and peripheral vasoconstriction. Shivering increases thermogenesis and replaces body heat losses, while peripheral vasoconstriction improves thermal insulation of the body and retards the rate of heat loss. A body of scientific literature supports the concept that prolonged and (or) repeated cold exposure, fatigue induced by sustained physical exertion, or both together can impair shivering and vasoconstrictor response to cold. The mechanisms accounting for this thermoregulatory impairment are not clear, but the possibility that changes in blood glucose availability or sympathetic responsiveness to cold due to exertion and fatigue merit further research.

scholarly journals Unique fur and skin structure in harbour seals ( Phoca vitulina )—thermal insulation, drag reduction, or both?

2015 ◽  
Vol 12 (104) ◽  
pp. 20141206 ◽  
Author(s):  
Nicola Erdsack ◽  
Guido Dehnhardt ◽  
Martin Witt ◽  
Andreas Wree ◽  
Ursula Siebert ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Heat Loss ◽  
Thermal Insulation ◽  
The Body ◽  
Body Parts ◽  
Skin Structure ◽  
Harbour Seals ◽  
Reduce Heat Loss ◽  
Mammalian Skin ◽  
New Type

Vertebrate surface structures, including mammalian skin and hair structures, have undergone various modifications during evolution in accordance with functional specializations. Harbour seals rely on their vibrissal system for orientation and foraging. To maintain tactile sensitivity even at low temperatures, the vibrissal follicles are heated up intensely, which could cause severe heat loss to the environment. We analysed skin samples of different body parts of harbour seals, and expected to see higher hair densities at the vibrissal pads as a way to reduce heat loss. In addition to significantly higher hair densities around the vibrissae than on the rest of the body, we show a unique fur structure of hair bundles consisting of broad guard hairs along with hairs of a new type, smaller than guard hairs but broader than underhairs, which we defined as ‘intermediate hairs’. This fur composition has not been reported for any mammal so far and may serve for thermal insulation as well as drag reduction. Furthermore, we describe a scale-like skin structure that also presumably plays a role in drag reduction.

Evaporative cooling: effective latent heat of evaporation in relation to evaporation distance from the skin

2013 ◽  
Vol 114 (6) ◽  
pp. 778-785 ◽  
Author(s):  
George Havenith ◽  
Peter Bröde ◽  
Emiel den Hartog ◽  
Kalev Kuklane ◽  
Ingvar Holmer ◽  
...  
Keyword(s):  
Heat Loss ◽  
Latent Heat ◽  
Direct Calculation ◽  
The Body ◽  
Base Layer ◽  
Cooling Power ◽  
Thermal Manikin ◽  
Evaporative Heat Loss ◽  
Moisture Evaporation ◽  
Heat Of Evaporation

Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available, which has found little use in recent literature. In this experiment a thermal manikin, (MTNW, Seattle, WA) was used to determine the effective cooling power of moisture evaporation. The manikin measures both heat loss and mass loss independently, allowing a direct calculation of an effective latent heat of evaporation (λeff). The location of the evaporation was varied: from the skin or from the underwear or from the outerwear. Outerwear of different permeabilities was used, and different numbers of layers were used. Tests took place in 20°C, 0.5 m/s at different humidities and were performed both dry and with a wet layer, allowing the breakdown of heat loss in dry and evaporative components. For evaporation from the skin, λeff is close to the theoretical value (2,430 J/g) but starts to drop when more clothing is worn, e.g., by 11% for underwear and permeable coverall. When evaporation is from the underwear, λeff reduction is 28% wearing a permeable outer. When evaporation is from the outermost layer only, the reduction exceeds 62% (no base layer), increasing toward 80% with more layers between skin and wet outerwear. In semi- and impermeable outerwear, the added effect of condensation in the clothing opposes this effect. A general formula for the calculation of λeff was developed.

Far IR Emission and Thermal Properties of Ceramics Coated Fabrics by IR Thermography

2006 ◽  
Vol 321-323 ◽  
pp. 849-852 ◽  
Author(s):  
Chung Hee Park ◽  
Myoung Hee Shim ◽  
Huen Sup Shim
Keyword(s):  
Far Infrared ◽  
The Body ◽  
Thermal Manikin ◽  
Evaporative Resistance ◽  
Clothing Insulation ◽  
Ir Camera ◽  
Warm Up ◽  
Coated Fabrics ◽  
Ir Emission ◽  
Body Heat

The purpose of this study was to develop the warm-up suit that is comfortable as well as has good thermal performance. The function of warm-up suit is to keep the body warm and thus to lose it’s weight by sweating. Ceramic powders, such as zirconium and magnesium oxide have been incorporated into the textile structures to utilize the far infrared radiation effect of ceramics, which heat substrates homogeneously by activating molecular motion. Thermal manikin tests were conducted to determine the clothing insulation and evaporative resistance of the selected warm-up suits. Also, the far IR emission effects of ceramics containing laminate on the body heat transfer were evaluated with the thermogram data using IR camera. The results showed that the ceramics inside laminate slightly increased the thermal insulation and the evaporative resistance. Thermogram showed that when the fabric was heated with the thermal manikin, surface mean temperatures of fabrics were increased as the ceramic incorporated, and the heat storage performance was confirmed.

The physiology of heat regulation

1995 ◽  
Vol 268 (4) ◽  
pp. R838-R850 ◽  
Author(s):  
P. Webb
Keyword(s):  
Heat Loss ◽  
Heat Production ◽  
Heat Content ◽  
The Body ◽  
Temperature Heat ◽  
Calorimetric Studies ◽  
Physiological Method ◽  
Related Level ◽  
Deep Body ◽  
Body Heat

Heat regulation is presented as the physiological method of handling metabolic heat, instead of temperature regulation. Experimental evidence of heat regulation from the literature is reviewed, including more than 20 years of calorimetric studies by the author. Changes in heat production are followed by slow exponential changes in heat loss, which produce changes in body heat storage. Heat balance occurs at many levels of heat production throughout the day and night, and at each level there is a related level of rectal temperature. Heat flow can be sensed by the transcutaneous temperature gradient. The controller for heat loss appears to operate like a servomechanism, with feedback from heat loss and possibly feedforward from heat production. Physiological responses defend the body heat content, but heat content varies over a range that is related to heat load. Changes in body heat content drive deep body temperatures.

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