An experimental investigation of moisture absorption and condensation in fibrous insulations under low temperature

Fan, Jintu; Cheng, Xiaoxiang; Chen, Yisong

doi:10.1016/s0894-1777(02)00305-9

Cited by 56 publications

(67 citation statements)

References 17 publications

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“…A class of commonly used Robin-type boundary conditions were introduced by Fan et al (2004) to approximate the experimental setup in Fan et al (2002), in which boundary conditions are defined by a combined simulation of cover layers and ambient environment. We use these Robin-type boundary conditions in this paper.…”

Section: (C) the Phase-change Ratementioning

confidence: 99%

Heat and sweat transport through clothing assemblies with phase changes, condensation/evaporation and absorption

Zhang

Sun

2011

Proc. R. Soc. A.

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The paper is concerned with the heat and sweat transport in porous textile media with complex phase changes, which is described as a non-isothermal, multi-phase and multicomponent fluid flow and governed by a nonlinear, degenerate and strongly coupled parabolic system. The phase change, condensation/evaporation and fibre absorption, play an important role in the design of functional clothing. In this paper, we present some more precise formulations on condensation/evaporation, fibre absorption and heat capacity to maintain the physical conservation of mass and energy. A typical clothing assembly with a hydrophobic batting material and two different types of cover is investigated numerically. Numerical results show that for the hydrophobic material, the evaporation and condensation zones arise simultaneously in the batting area and that the proposed formulations are more realistic to describe the phase change. Existence and uniqueness of a classical positive solution for the incompressible model are also proved. existence of solution

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Section: (C) the Phase-change Ratementioning

confidence: 99%

Heat and sweat transport through clothing assemblies with phase changes, condensation/evaporation and absorption

Zhang

Sun

2011

Proc. R. Soc. A.

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“…Several works in literature report studies on the heat and mass transport in textile structures [1][2][3][4][5][6][7][8][9]. Le et al [1] and Gibson and Charmchi [9] used volume-averaging techniques to address the interaction between heat and mass transfer, and track concentration and temperature fronts as moisture is transported through hygroscopic materials.…”

Section: Introductionmentioning

confidence: 99%

“…However, the measurement of some of these parameters is not straightforward and requires access to complex/expensive experimental facilities [1,9]. Furthermore, in some of the available literature [1][2][3][4][5][6][7][8][9], it is not entirely clear how some parameters are determined (e.g. porosity, tortuosity) which renders difficult the comparison of results from different authors and may hamper a faster adoption of numerical approaches in clothing development activities.…”

Section: Introductionmentioning

confidence: 99%

On the determination of parameters required for numerical studies of heat and mass transfer through textiles – Methodologies and experimental procedures

Neves

Campos

Mayor

2015

International Journal of Heat and Mass Transfer

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a b s t r a c tThe aim of this study was to develop methodologies and experimental procedures to determine textile parameters required in numerical approaches of heat and mass transfer through textiles. Privileging techniques usually available in textile/clothing laboratories, experimental approaches were defined that allow to estimate all required parameters, while taking into consideration water presence in the fibres and hence the effect of fibres hygroscopic properties. Numerical models usually require values of textile thickness, fibre fraction, and tortuosity, as well as knowledge of the boundary conditions, e.g. convective heat and mass transfer coefficients. To calculate these parameters, thickness, weight, and volume of textile samples were measured, whereas convective and textile evaporative resistances were determined by indirect measurements. Results were obtained for four distinct textile samples (made of wool, cotton, and a mixture of materials), of different hydrophilic nature. When the obtained parameters were incorporated in a numerical model and numerical predictions of temperature and humidity were compared with experimental data obtained during measurements of fabric evaporative resistance, it was shown that the predictions were accurate; this lends support to the developed methods and approaches.Since an uncertainty in the measured parameters can compromise the accuracy of numerical predictions, a sensitivity analysis was conducted to study the influence of deviations in the model input parameters and of assumptions regarding water presence in the fibres, on the predictions of heat and mass transfer rates. The results show that a deviation in textile weight and thickness as well as the assumption of no water retained in fibres during their characterisation, have a significant effect on the predicted heat transfer and water distribution over time. Moreover, a deviation in the total evaporative resistance, convective evaporative resistance, and sorption rate factor has great influence on the heat flux obtained in the initial period of testing.

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“…The measured thermal conductivities showed that the coconut fibers and groundnut coquets may be used as thermal insulation for the tested temperature range. Fan et al [2] reported an experimental investigation of the temperature and water content distribution within porous fibrous battings sandwiched by an inner and outer layer of thin covering fabrics using a novel sweating, guarded hot plate. They found that most of the change in temperature occurred within the first half hour and moisture absorption by the hygroscopic fibers affected the temperature distribution.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of moist-air transport through natural materials porous media

Conté¹,

Xiao²

2006

WIT Transactions on Ecology and the Environment, Vol 87

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Experimental investigations were conducted to characterize the moisture absorption of two different natural materials (coconut fibres and groundnut coquets). Two experimental samples were made: one with groundnut coquets (composed by void space and grain) and the other sample was made with coconut fibres (composed by void space and fibres). The samples were multi-layered sandwiches bounded on the top by ice while the bottom surface was exposed to the vapour with temperature close to 100 o C. The percentage of water accumulation due to vapour absorption was calculated for each layer after a pre-set time of experiment (1h, 2h,…). The water content within both the coconut fibres and groundnut coquet increased with time. For the groundnut coquet sample the water was transferred mainly by diffusion through the solid; and in the coconut fibres sample with higher porosity, the water transferred by diffusion through void space was the most important. Since water is a better thermal medium, the thermal conductivity of the soaked insulation would increase and the insulating value of the material would be destroyed.

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An experimental investigation of moisture absorption and condensation in fibrous insulations under low temperature

Cited by 56 publications

References 17 publications

Heat and sweat transport through clothing assemblies with phase changes, condensation/evaporation and absorption

Heat and sweat transport through clothing assemblies with phase changes, condensation/evaporation and absorption

On the determination of parameters required for numerical studies of heat and mass transfer through textiles – Methodologies and experimental procedures

Experimental investigation of moist-air transport through natural materials porous media

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