A study of heat transfer through clothing assemblies
The work presented in this thesis is devoted to further understanding heat transfer through clothing under different circumstances, in order to provide guidelines for the design and construction of clothing with regard to thermal comfort. In one part of this work, studies were concentrated on the clothing thermal insulation in windy conditions. In this part, a newly designed cylindrical togmeter and a theoretical model have been developed. The numerical solution derived from the theoretical model agrees well with the experimental findings from the cylindrical togmeter in a wind tunnel. The heat transfer mechanisms involved in the wind induced reduction of clothing thermal insulation have been better understood by examining the experimental and theoretical results. The effects of wind velocity, air permeability and stiffness of the outer fabrics, air permeability and thickness of the inner fibrous battings, and the dimensions of the human body on the clothing thermal insulation have also been examined and discussed. Furthermore, based on the understanding of the mechanism of air penetration into permeable clothing assemblies, methods have been proposed for the design and construction of wind resistant protective clothing by using permeable outer fabrics. These methods were evaluated on the cylindrical togmeter and are believed to have important practical values. The other part of this work was focused on the development and laboratory use of a fabric manikin. The "skin" of the manikin was made of coated water-proof fabric, and heated water was circulated inside the "body". The arms and legs of the manikin could be moved to simulate walking. The manikin was very cheap to construct when compared with that of a copper manikin and can be widely applied for routine tests for outdoor and military garments subject to some modifications in its design. With this fabric manikin, a series of experiments have been conducted to investigate the effects of body motion, clothing design and environmental conditions on the thermal insulation of clothing. Some useful information for the design of functional clothing and for the prediction of the thermal stress of a clothed person in different environmental conditions has been provided through this investigation.