Factors influencing thermal resistance of a down sleeping bag

Abstract

PurposeTo have a better understanding of the heat transfer mechanisms in a sleeping bag and to investigate the factors influencing thermal resistance of a down sleeping bag.Design/methodology/approachThe mechanism of heat transfer in a sleeping bag was discussed in this paper. The thermal resistances of 24 samples were investigated. Besides, the relation between fill weight and thermal resistance, and that between the air permeability of fabric and thermal resistance, as well as that between down filling rate and thermal resistance were analyzed.FindingsThe results showed that thermal resistances of samples varied from 0.35 to 0.8 m2 K/W. The fill weight was the most important factor of thermal resistance of sleeping bag and the relation between fill weight and thermal resistance matched well with cubic function. A multiple regression formula was proposed, which with thermal resistance as a dependent variable and with air permeability of fabric, down filling rate, fill weight as independent variables.Originality/valueThermal properties of a sleeping bag were analyzed through simplified basic unit under simplified environment conditions, which was necessary for building the first stage of systematic study of thermal performance of a sleeping bag.

Analysis and evaluation of the thermal performance of combinations of suits and life jackets in water

“…There are three ways in which heat can be exchanged between the body and the environment: conduction (C), radiation (R) and convection (K). 18 The heat transfer process of clothes in water is a mixture of these three ways: heat passed by the fibers, heat radiated between the fibers and the water and heat transferred through the convection of the water. 19 Forced convection can be ignored because this study investigated thermal resistance under hydrostatic conditions.…”

“…When clothes become partially or completely wet, thermal insulation is an important physical characteristic to quantify their thermal comfort. 18 In the case of a victim falling into water, heat transfer occurs primarily in the part of the body in contact with the surface of the clothing. Since the clothes isolate direct heat transfer between the human body and the surrounding environment, the clothes act as an intermediate medium to prevent direct heat transfer from the surface of the human skin.…”

Thermal resistance prediction of aerogel fabrics after repeated washing based on small-sample data

“…Due to their complexity and requirement for larger sample sizes, machine learning methodologies are less suited for small-sample problems related to aerogel fabrics than the gray method. 53,54 Several studies [8][9][10]14,[16][17][18] have identified influencing factors of fabrics following repetitive washing based on previous knowledge, neglecting the variable contributions throughout the washing process. Real-world projects exhibit dynamic and changing correlations between independent and dependent variables, significantly impacting the accuracy of aerogel fabric thermal resistance predictions.…”

“…8,9 The relationships between fabric characteristics (e.g., weaving patterns, fabric mass, thickness, porosity, and hydrophobicity) and thermal resistance have been rigorously investigated over several decades. Prior studies have proposed various prediction models for the thermal properties of fabric products, such as statistical models, [8][9][10][11][12][13][14] artificial neural networks, [15][16][17][18] theoretical models of heat transfer, [19][20][21] and finite element models. [22][23][24] More recent studies 3,25,26 have examined the effects of recurrent washing on the thermal insulation performance of textiles, confirming a strong correlation between thermal resistance and parameters such as thickness, weight, air permeability, and porosity.…”

“…Thermal resistance, a crucial determinant of comfort attributes, is influenced by numerous factors, including yarn structure, air permeability, thickness, thermal absorption, and moisture content. 8,9 The relationships between fabric characteristics (e.g., weaving patterns, fabric mass, thickness, porosity, and hydrophobicity) and thermal resistance have been rigorously investigated over several decades. Prior studies have proposed various prediction models for the thermal properties of fabric products, such as statistical models, [8][9][10][11][12][13][14] artificial neural networks, [15][16][17][18] theoretical models of heat transfer, [19][20][21] and finite element models.…”