scholarly journals Human Machine and Thermoelectric Energy Scavenging for Wearable Devices

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Vladimir Leonov
Keyword(s):  
Thermal Properties ◽  
Heat Flow ◽  
Thermal Resistance ◽  
Wearable Devices ◽  
The Body ◽  
Energy Scavenging ◽  
Wearable Electronics ◽  
Ambient Temperatures ◽  
Thermoelectric Energy ◽  
Temperature Heat

Thermal properties of humans were studied in the case where a small-size energy scavenger is placed on the body. In such a case, the human being serves as a heat source for the thermopile of the scavenger, but the latter serves as a thermally insulating object. As a result, the body properties, namely, the skin temperature, heat flow, and thermal resistance locally change. This is the result of redirection of heat flow inside the body to colder zones because of thermal insulation provided by the scavenger. Increased thermal resistance of human body, in turn, affects the design of the scavenger. The analysis of such scavenger performed for ambient temperatures of 0°C to 25°C shows that it could reach competitive performance characteristics and replace batteries in low-power wearable electronics. A simulated power of up to 60 μW/cm2 at 0°C has been validated by using wearable thermoelectric modules.

Temperature regulation and heat dissipation during flight in birds

1976 ◽  
Vol 65 (2) ◽  
pp. 471-482 ◽  
Author(s):  
J. R. Torre-Bueno
Keyword(s):  
Steady State ◽  
Heat Flow ◽  
Skin Temperature ◽  
Core Temperature ◽  
Heat Dissipation ◽  
Sturnus Vulgaris ◽  
The Body ◽  
Ambient Temperatures ◽  
Flow Through ◽  
Animal Skin

Core and skin temperature were measured by radiotelemetry in starlings (Sturnus vulgaris) during 30 min flights in a wind tunnel. Core temperature was independent of ambient temperature from 0 to 28 degrees C. The temporal mean of the monitored core temperature during flight was 42-7 degrees C in one bird and 44-0 degrees C in another. These temperatures are 2-4 degrees C higher than the resting temperature in starlings, and are among the highest steady-state temperatures observed in any animal. Skin temperature on the breast was within a few degrees of core temperature. In some locations skin temperature was higher at low ambient temperatures than at intermediate ambient temperatures. An analysis of the data shows that a high core temperature does not function as an aid to head dissipation. On the contrary, insulation is adjusted to maintain a high temperature, presumably because it is necessary for flight. The increase in skin temperature at low ambient temperatures is believed to be a result of a decrease in heat flow through the breast feathers brought about by feather adjustments, to compensate for an unavoidable increase in heat flow in unfeathered or poorly feathered parts of the body.

Influence of Structure Variation and Finishing on Woven Fabric Thermal Properties

2018 ◽  
Vol 26 (1(127)) ◽  
pp. 120-124
Author(s):  
Iwona Frydrych ◽  
Goran Demboski
Keyword(s):  
Thermal Properties ◽  
Heat Flow ◽  
Thermal Resistance ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Weft Yarn ◽  
Flow Density ◽  
Heat Flow Density ◽  
Stationary Heat ◽  
Yarn Count

The paper investigates the influence of fabric structure variations and finishing on the thermal properties of woven fabrics for a tailored garment. Four distinctive pairs of fabrics were investigated, where the weft density, weft yarn count or type and finishing were varied within the fabrics in each pair. Several thermal properties such as conductivity, diffusivity, absorptivity, resistance, the ratio of maximal and stationary heat flow density and the stationary heat flow density were measured using an Alambeta device. The results obtained showed that variation of the weft yarn count and finishing have a significant effect on several thermal properties. Increasing the weft count increased the thermal conductivity, absorptivity, resistance and the ratio of maximal and stationary heat flow density. The application of oilproof and waterproof finishing affected thermal diffusivity, thermal absorptivity and thermal resistance. Milled finishing contributed to increasing the thermal resistance.

scholarly journals Thermo-Physiological Comfort Properties of Sportswear with Different Combination of Inner and Outer Layers

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6863
Author(s):  
Desalegn Atalie ◽  
Pavla Tesinova ◽  
Melkie Getnet Tadesse ◽  
Eyasu Ferede ◽  
Ionuț Dulgheriu ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Water Vapor ◽  
Heat Flow ◽  
Thermal Resistance ◽  
Outer Layer ◽  
Water Vapor Permeability ◽  
Flow Density ◽  
Vapor Permeability ◽  
Heat Flow Density ◽  
Time Activity

Consumers expect high-performance functionality from sportswear. To meet athletic and leisure-time activity requirements, further research needs to be carried out. Sportswear layers and their specific thermal qualities, as well as the set and air layer between materials, are all important factors in sports clothing. This research aims to examine the thermal properties of sports fabrics, and how they are affected by structure parameters and maintained with different layers. Three inner and four outer layers of fabric were used to make 12 sets of sportswear in this study. Before the combination of outer and inner layers, thermal properties were measured for each individual layer. Finally, the thermal resistance, thermal conductivity, thermal absorptivity, peak heat flow density ratio, stationary heat flow density, and water vapor permeability of bi-layered sportswear were evaluated and analyzed. The findings show that sportswear made from a 60% cotton/30% polyester/10% elastane inner layer and a 100% polyester outer layer had the maximum thermal resistance of 61.16 (×103 K·m2 W−1). This performance was followed by the sample made from a 90% polyester/10% elastane inner layer and a 100% polyester outer layer, and the sample composed of a 100% elastane inner layer and a 100% polyester outer layer, which achieved a thermal resistance value of 60.41 and 59.41 (×103 K·m2 W−1), respectively. These results can be explained by the fact that thicker textiles have a higher thermal resistance. This high-thermal-resistance sportswear fabric is appropriate for the winter season. Sportswear with a 90% polyester/10% elastane inner layer had worse water vapor resistance than sportswear with a 60% cotton/30% polyester/10% elastane and a 100% elastane layer. Therefore, these sports clothes have a higher breathability and can provide the wearers with very good comfort. According to the findings, water vapor permeability of bi-layered sportswear is influenced by geometric characteristics and material properties.

Computational models of filtration gas combustion

2017 ◽  
Vol 32 (2) ◽  
Author(s):  
Yuri M. Laevsky ◽  
Tatyana A. Nosova
Keyword(s):  
Heat Flow ◽  
Numerical Experiments ◽  
Computational Models ◽  
Two Dimensional ◽  
Multidimensional Model ◽  
Gas Combustion ◽  
Total Enthalpy ◽  
Diffusive Flow ◽  
Temperature Heat ◽  
The One

AbstractA multidimensional model of filtration gas combustion is presented. The model is based on the system of conservation laws of ‘temperature – heat flow’, ‘mass–diffusive flow’ types with introducing the concept of total enthalpy flow. Results of numerical experiments are presented for the one- and two-dimensional problems for different conditions and parameters.

Inhibiting ventilatory evaporation produces an adaptive increase in cutaneous evaporation in mourning doves Zenaida macroura

1999 ◽  
Vol 202 (21) ◽  
pp. 3021-3028 ◽  
Author(s):  
T.C. Hoffman ◽  
G.E. Walsberg
Keyword(s):  
Skin Surface ◽  
The Body ◽  
Evaporative Heat Loss ◽  
Evaporative Water ◽  
Zenaida Macroura ◽  
Ambient Temperatures ◽  
Rapid Adjustment ◽  
Mourning Doves ◽  
A Minor ◽  
Cutaneous Evaporation

We tested the hypothesis that birds can rapidly change the conductance of water vapor at the skin surface in response to a changing need for evaporative heat loss. Mourning doves (Zenaida macroura) were placed in a two-compartment chamber separating the head from the rest of the body. The rate of cutaneous evaporation was measured in response to dry ventilatory inflow at three ambient temperatures and in response to vapor-saturated ventilatory inflow at two ambient temperatures. At 35 degrees C, cutaneous evaporation increased by 72 % when evaporative water loss from the mouth was prevented, but no increase was observed at 45 degrees C. For both dry and vapor-saturated treatments, cutaneous evaporation increased significantly with increased ambient temperature. Changes in skin temperature made only a minor contribution to any observed increase in cutaneous evaporation. This indicates that Z. macroura can effect rapid adjustment of evaporative conductance at the skin in response to acute change in thermoregulatory demand.

Effect of Changes in Ambient Temperature on Spontaneous Activity, Food Intake and Body Weight of Goldthioglucose-Obese and Nonobese Mice

1957 ◽  
Vol 188 (3) ◽  
pp. 435-438 ◽  
Author(s):  
M. J. Fregly ◽  
N. B. Marshall ◽  
J. Mayer
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Ambient Temperature ◽  
The Body ◽  
Lower Body ◽  
Obese Mice ◽  
Ambient Temperatures ◽  
Exposure To Cold ◽  
Running Activity ◽  
Body Weights

Goldthioglucose-obese mice cannot adjust their food intake to meet the increased energy requirements due to cold. At all ambient temperatures above 15°C the spontaneous running activity of these animals is less than that observed for nonobese controls. Activity of obese mice is maximal at 19°C and minimal at 15°C or lower. Body weights decrease during exposure to cold. In contrast to that of obese mice, running activity of nonobese controls is maximal at an ambient temperature of 25°C but nearly ceases at 15°C or lower. The food intake of these animals increases in the cold and remains elevated even at temperatures at which activity decreases. The body weight of nonobese controls is either maintained constant or increases during exposure to cold air.

scholarly journals Breathable Materials for Triboelectric Effect-Based Wearable Electronics

2018 ◽  
Vol 8 (12) ◽  
pp. 2485 ◽  
Author(s):  
Congju Li ◽  
Ran Cao ◽  
Xiuling Zhang
Keyword(s):  
Recent Progress ◽  
Dielectric Materials ◽  
Wearable Devices ◽  
Wearable Electronics ◽  
Practical Application ◽  
Metal Mesh ◽  
Frictional Materials ◽  
Nanofiber Membranes ◽  
Materials Used ◽  
Triboelectric Effect

Wearable electronics are believed to be the future of the next-generation electric devices. However, the comfort of current wearable devices is greatly limited due to the use of airtight materials, which may even lead to inflammation of the skin. Therefore, breathable, skin-friendly materials, are highly desired for wearable devices. Here, the recent progress of the breathable materials used to fabricate skin-friendly electronics is reviewed by taking triboelectric effect-based wearable electronics as a typical example. Fibers, yarns, textiles, and nanofiber membranes are the most popular dielectric materials that serve as frictional materials. Metal mesh, silver yarn, and conductive networks made up of nanomaterial are preferred as air-permissive electrodes. The breathable materials for skin-friendly wearable electronics summarized in this review provide valuable references for future fabrication of humanized wearable devices and hold great significance for the practical application of wearable devices.

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