Muhammad Owais Raza Siddiqui

Computational analysis of effective thermal conductivity of microencapsulated phase change material coated composite fabrics

Microencapsulated phase change materials have been widely used as filler material to develop thermoregulating textile composites. Phase change material has unique property of latent heat that can absorb and release energy over constant temperature range. In this work a method is developed to predict the effective thermal conductivity of microencapsulated phase change material coated composite woven fabrics via finite element analysis. For this purpose unit cell of microencapsulated phase change materials as coated material and woven fabrics were developed and analysed by applying different boundary conditions. Validation of the models was carried out on the basis of strong correlation in effective thermal conductivity values of the microencapsulated phase change materials coated composite fabrics between experimental results and the predicted results from post-processing calculation by finite element method.

Automated model generation of knitted fabric for thermal conductivity prediction using finite element analysis and its applications in composites

Thermal property of clothing has significant impact on thermal comfort of the wearers. In an extreme working condition body releases a lot of heat and sweat, in order to keep the body dry and at normal temperature these heat and sweat should be released in the environment. The thermal comfort of the fabrics mainly depends on how well it transmits heat and moisture to the environment. In this work finite element models have been developed to predict the thermal conductivity of plain weft knitted fabrics. Fabrics with different stitch density and yarn count were used in this work. A unit cell model of the fabrics was developed by using the actual geometrical parameters. Material orientation of the yarn was used for assigning the thermal conductivity of each element in the yarn. Boundary conditions were applied on unit cell of the fabrics for the determination of thermal conductivity. The geometrical models of the fabrics were generated by a plug-in which was developed in Abaqus/computer aided engineering using Python script. It has been found that thermal conductivity between the predicted results obtained from finite element analysis and experimental results from an in-house developed device is highly correlated. Furthermore, the application of geometrical model in different areas has been discussed, and technique is developed for the prediction of effective thermal conductivity of plain weft knitted composite fabric.

Thermal analysis of conventional and performance plain woven fabrics by finite element method

The research reports the development of geometrical models of woven fabric structures and evaluation of fabric thermal properties by using finite element method. A mesoscopic scale modelling approach was used to investigate the effective thermal conductivity and thermal resistance of woven textile structures. Various techniques, including scanning electron microscopy and experimental methods, have been adopted to obtain the actual three-dimensional parameters of the fabrics for finite element analysis. The research revealed that the thermal anisotropy of fibres, fibres material orientation and temperature-dependent thermal conductivity of fibre has a significant impact on the effective thermal conductivity of fabrics because experimental and simulated results were highly correlated with the consideration of above-mentioned factors.

Geometrical modelling and thermal analysis of nonwoven fabrics

Nonwoven fabric can be produced for thermal insulation. It has low fibre volume fraction. Thermal insulation property of fibrous materials depends on not only the thermal conductivity of fibre but also the entrapped static air. If fibre volume fraction is low in fibrous assembly it means that more air in the volume, therefore, the insulation property of the fabric increases, or vice versa. In this research thermal bonded nonwoven fabrics were used to analyse the heat transfer phenomena and predict the effective thermal conductivity and thermal resistance by using finite element method. Finite element models of nonwoven fabrics were created by two techniques: 3D reconstruction and solid modelling. For validation purpose, the effective thermal conductivity results obtained from an in-house developed instrument were compared with predicted results from the developed finite element models. Furthermore, this research work also contains an investigation of the effect of fibre volume fraction and thermal conductivity of fibre on the overall heat transfer of nonwoven structures.

Development of Experimental Setup for Measuring the Thermal Conductivity of Textiles

The thermophysical properties of textile materials are very important in helping to understand the thermal comfort of fabrics for clothing and technical textiles. An experimental setup for the measurement of the thermal conductivity of fabrics was developed based on the heat flow meter principle. The setup was considered highly accurate and reliable based on the low absolute error, high correlation coefficient, and the coefficient of determination between the results from the setup and commercially available devices. The setup is easy to use for testing any textile-based materials and their composites.

Conjugate heat transfer analysis of knitted fabric

The thermal properties of fabric have significant impact on thermal comfort of the wearers. This research work covers the development of geometrical models of plain weft knitted fabric structures and evaluation of the thermal properties by using the fluid surface interaction technique. The results obtained from the numerical method were compared with the experimental results, and it was found that they were highly correlated. Furthermore, the validated models were utilized to evaluate the velocity and temperature profile of air at out-plane created over the surface of knitted fabric.

Development of plug-ins to predict effective thermal conductivity of woven and microencapsulated phase change composite

The thermal property of textile structures plays an important role in the understanding of thermal behaviour of the clothing. In this work, user-friendly GUI plug-ins have been developed to generate both microscopic and mesoscopic scale models for finite element analysis. The plug-ins were developed by using Abaqus/CAE as a platform. The GUI Plug-ins enable automatic model generation and prediction of the effective thermal conductivity of woven composite and microencapsulated Phase Change Materials composites via finite element analysis by applying boundary conditions. The predicted effective thermal conductivities from plug-ins have been compared with the results obtained from published experimental research work based on an established mathematical model. They are correlated well. Moreover, the influence of phase change materials on heat transfer behaviour of microencapsulated Phase Change Materials composites was further analysed.