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In the present work, the thermal insulation characteristics of multilayered mittens were studied in different airflow conditions.

In this study, the thermal behavior of four groups of mittens consisting of one two-layer and three three-layer mittens containing nonwoven wadding materials with various weights and thicknesses was investigated during the exposure to airflows with different speeds. In order to evaluate the correlation between the heat transfer rates of different mittens with the human perception of cold, a set of pair-comparison tests was performed using Thurstone's law of comparative judgment.

The analysis of the results revealed that by an increment in the weight and the thickness of the wadding material, the thermal protection performance of mittens improves. Moreover, in the presence of airflow and by increasing its speed, due to the forced convective heat loss, the outer surface temperature of the mittens decreases and therefore the conductive heat transfer rate rises. This fact leads to the transfer of higher quantity of body warmth to the environment and thus feeling of coldness. According to the results, there was a proper correlation between the subjective perception of cold and the heat transfer rate of mittens. The statistical analysis of the results clarified that the effect of mitten's structural parameters and the airflow speed on the thermal protection behavior of mittens are significant at the confidence range of 95%.

Mitten is one of the important personal protective clothing, especially in cold environments. Thus, the thermal resistance of them has a prominent role in the protection of the hands and fingers from cold and frostbiting.

This paper aims to deal with the thermal resistance of multilayer nonwovens. The effect of fibre denier, cross-sectional shape and positioning within the layers were analysed with respect to the thermal resistance. Moreover, effect of compression on thermal resistance of the multilayer nonwoven structure have also be studied.

The study involves multiple layering of thermal bonded nonwoven webs and the effect of fibre denier and positioning of different nonwovens from the hot plate. To avoid the increase in thermal resistance because of the air gaps between layers, the nonwovens were enclosed within an acrylic frame to compress them to a thickness of 12 mm. Compressional behaviour of the nonwovens were tested at a rate of 5 mm/min with peak compressive load of 50 N. Multilayer nonwoven assemblies were tested for thermal resistance with compressive pressure of 3.5 gf/cm² and compared with that tested at zero pressure.

In the study, three-layered nonwoven structure, provided better thermal resistance than their single component counterparts. The structural characteristic of the multilayer nonwovens affected the conductive, convective and the radiative heat transfer. In a multi-layer nonwoven, the top most layer should have the finest fibre as possible. Second preference may be given to the middle and followed by bottom layers in terms of fibre fineness. However, fine solid fibres performed poorly in terms of compression and recovery resulting in poor thermal resistance under compressive load.

The experimental approach of controlling thickness while evaluating the thermal resistance will help in nullify the effect of air gaps between the layer interface, thus focussing on the effect of fibre denier and the positioning of nonwovens. This paper also discusses the unique properties of fine solid fibre and hollow fibres and their role in providing better thermal insulation for extreme cold weather applications.

To understand the thermal insulation of four common structures of sleeping bags and factors influencing the thermal insulation as well as the thermal comfort of people who use four kinds of sleeping bag structures.

Four samples corresponding to four common sleeping bag structures were made and their thermal properties were investigated through a combination of objective instrument measurement and subjective human subject tests.

The porosity of the samples and the length of the interlining had a main impact on the thermal resistances of the four sleeping bag structures. The thermal sensation ratings and the thermal resistances had good consistency. There was a strong correlation between human physiological parameters and thermal sensation evaluation. The male and female have significant differences in thermal sensation of different structures of sleeping bags.

Instrument measurement and human subject tests were combined to study the thermal properties of sleeping bag structures, which had little attention in the past in research fields.

The purpose of this paper is to measure the thermal insulation of protective clothing with multilayer gaps in low-level heat exposures.

Nine different combinations of protective clothing systems with multiple air gaps are used to measure the thermal insulation by a self-designed bench-scale test apparatus in different levels of an external thermal radiation of 2-10 kW/m2. The outside and inside surface temperatures of each fabric layer are also measured to calculate the local thermal insulation of each fabric layer and each air gap.

The results show that the total thermal insulation of protective clothing under thermal radiation is less than that in normal environments, and the exposed thermal radiation will worsen the total thermal insulation of the multilayer fabric systems. Air gap plays a positive role in the total thermal insulation, and thus provides the enhanced thermal protection. It is also suggested that the local resistance of the air gap closer to the external thermal radiation is more easily affected by the thermal radiation, due to the different heat transfer ways in the fabric system and the external thermal radiation.

Effects of air gap on the thermal insulation of protective clothing, and contribution of the local thermal resistance of each fabric layer and each air gap to the total thermal insulation.

In this paper, a method of designing flexible multilayer insulation is analyzed and discussed, with focus on reducing the three basic modes of heat transfer (thermal radiation, solid spacer and residual gas conduction). The foundation for designing the new flexible thermal insulation material is provided. The insulation performances of different types (by choosing different reflection shields and spacers) of flexible multilayer insulation materials are obtained through measurements using a KES-F7 Thermal Labo II apparatus. The thermal performance of flexible multilayer insulation materials at different layers are also presented, and the best is about 20∼25 layers. To improve the thermal performance of multilayer insulation materials, treble spacers between double aluminized shields are applied. Aluminized shields with air, meshes, wool fibres, etc. are compared with each other. The aluminized shields with meshes fixed with down can reduce thermal contact, which reduces the radiation heat transfer more fully and can be more steady than the other spacers in the project applications. With the same layers and spacers, the thermal conductivity of crinkled aluminized shields is lower than that of the smooth aluminized shields. The effects of compressive loads on layer density and thermal performance are also investigated.

The purpose of this study is to achieve lower and lower temperature as infrared sensors works faster and better used for space application. For getting good quality images from space, the infrared sensors are need to keep in cryogenic temperature. Cooling to cryogenic temperatures is necessary for space-borne sensors used for space applications. Infrared sensors work faster or better at lower temperatures. It is the need for time to achieve lower and lower temperatures.

This study presents the investigation of the critical Stirling cryocooler parameters that influence the cold end temperature. In the paper, the design approach, the dimensions gained through thermal analysis, experimental procedure and testing results are discussed.

The effect of parameters such as multilayer insulation, helium gas charging pressure, compressor input voltage and cooling load was investigated. The performance of gold-plated and aluminized multilayer insulation is checked. The tests were done with multilayer insulation covering inside and outside the Perspex cover.

By using aluminized multilayer insulation inside and outside the Perspex cover, the improvement of 16 K in cool-down temperature was achieved. The cryocooler is charged with helium gas. The pressure varies between 14 and 18 bar. The optimum cooling is obtained for 17 bar gas pressure. The piston stroke increased as the compressor voltage increased, resulting in total helium gas compression. The optimum cool-down temperature was attained at 85 V.

The cryocooler is designed to achieve the cool-down temperature of 2 W cooling load at 100 K. The lowest cool-down temperature recorded was 105 K at a 2 W cooling load. Multilayer insulation is the major item that keeps the thermal radiation from the sun from reaching the copper tip.

The purpose of this study is to optimize multilayer vacuum thermal insulation (MLI) of modern high-weight spacecrafts. An adequate mathematical simulation of heat transfer in the MLI is impossible if there is no available information on the main insulation properties.

The results of experiments in thermo-vacuum facilities are used to re-estimate some radiative properties of metallic foil/metalized polymer foil and spacer on the basis of the inverse problem solution. The experiments were carried out for the sample of real MLI used for the BP-Colombo satellite (ESA). The recently developed theoretical model based on neglecting possible near-field effects in radiative heat transfer between closely spaced aluminum foils was used in theoretical predictions of heat transfer through the MLI.

A comparison of the computational results and the experimental data confirms that there are no significant near-field effects between the neighboring MLI layers. It means that there is no considerable contradiction between the far-field model of radiative transfer in MLI and the experimental estimates.

An identification procedure for mathematical model of the multilayer thermal insulation showed that a modified theoretical model developed recently can be used to estimate thermal properties of the insulation at conditions of space vacuum.

The purpose of this paper is to explore the effects of wind direction and ease allowance on thermal comfort in sportswear.

The effects of wind direction (front, side, back and calm (no wind) 1.5 m/s) and seven magnitudes of ease allowance on sportswear thermal insulation and surface temperature were investigated. An 11 zones’ thermal manikin was used to acquire the static thermal insulation. Surface temperature was captured by a thermal imager.

The results showed that the wind was a significant effect on thermal performance, however, wind direction effect was only significant in the segment covered with multilayer fabric, such as the abdomen and hip (p=0.034). Although the ease allowance influenced the overall thermal insulation obviously, the difference between seven sizes suits was not significant. Nevertheless, the ease allowance affected the surface temperature of chest and back significantly (p=0.023, 0.007). Correlation between thermal insulation and surface temperature was negative, and correlation level was degraded when affected by wind factor.

Sportswear’s fabric and style did not discussed as effect factors. It would be taken into accounted in the future research.

Wind direction impact thermal comfort in multilayer regions significantly. It is a reference to improve sportswear’s comfort design.

The purpose of this paper is to develop artificial neural networks (ANNs) allowing us to simulate the local thermal insulation of clothing protecting against cold on a basis of the characteristics of materials and design solutions used.

For this purpose, laboratory tests of thermal insulation of clothing protecting against cold as well as thermal resistance of textile systems used in the clothing were performed. These tests were conducted with a use of thermal manikin and so-called skin model, respectively. On a basis of results gathered, 12 ANNs were developed that correspond to each thermal manikin’s segment besides hands and feet which are not covered by protective clothing.

In order to obtain high level of simulations, optimization measures for the developed ANNs were introduced. Finally, conducted validation indicated a very high correlation (above 0.95) between theoretical and experimental results, as well as a low error of the simulations (max 8 percent).

The literature reports addressing the problem of modeling thermal insulation of clothing focus mainly on the impact of the degree of fit and the velocity of air movement on thermal insulation properties, whereas reports dedicated to modeling the impact of the construction of clothing protecting against cold as well as of diverse material systems used within one design of clothing on its thermal insulation are scarce.

The purpose of this paper is to develop a numerical simulation method based on the transient upstream finite element method (FEM) and Schottky emission theory to reveal the distribution characteristics of space charge in oil-paper insulation.

The main insulation medium of the converter transformer in high voltage direct current transmission is oil-paper insulation. However, the influence of space charge is difficult to be fully considered in the insulation design and simulation of converter transformers. To reveal the influence characteristics of the space charge, this paper proposes a numerical simulation method based on Schottky emission theory and the transient upstream FEM. This method considers the influence of factors, such as carrier mobility, carrier recombination coefficient, trap capture coefficient and diffusion coefficient on the basis of multi-physics field coupling calculation of the electric field and fluid field.

A numerical simulation method considering multiple charge states is proposed for the space charge problem in oil-paper insulation. Meanwhile, a space charge measurement platform based on the electrostatic capacitance probe method for oil-paper insulation structure is built, and the effectiveness and accuracy of the numerical simulation method is verified.

A variety of models are calculated and analyzed by the numerical simulation method in this paper, and the distribution characteristics of the space charge and total electric field in oil-paper insulation medium with single-layer, polarity reversal of plate voltage and double-layer are obtained. The research results of this paper have the guiding significance for the engineering application of oil-paper insulation and the optimal design of converter transformer insulation.