Advances in the optimisation of apparel heating products: A numerical approach to study heat transport through a blanket with an embedded smart heating system

Abstract

h i g h l i g h t sA numerical approach to optimise the performance of heating products is described. The approach was used to investigate the heat transport across a heating blanket. Several parameters and properties of textiles and of heating system were studied. Optimal compromise between the thermal performance of the product and the temperature oscillation along its surface. a r t i c l e i n f o The optimisation of the performance of products with smart/active functionalities (e. g. in protective clothing, home textiles products, automotive seats, etc.) is still a challenge for manufacturers and developers. The aim of this study was to optimise the thermal performance of a heating product by a numerical approach, by analysing several opposing requirements and defining solutions for the identified limitations, before the construction of the first prototype. A transfer model was developed to investigate the transport of heat from the skin to the environment, across a heating blanket with an embedded smart heating system. Several parameters of the textile material and of the heating system were studied, in order to optimise the thermal performance of the heating blanket. Focus was put on the effects of thickness and thermal conductivity of each layer, and on parameters associated with the heating elements, e.g. position of the heating wires relative to the skin, distance between heating wires, applied heating power, and temperature range for operation of the heating system. Furthermore, several configurations of the blanket (and corresponding heating powers) were analysed in order to minimise the heat loss from the body to the environment, and the temperature distribution along the skin. The results show that, to ensure an optimal compromise between the thermal performance of the product and the temperature oscillation along its surface, the distance between the wires should be small (and not bigger than 50 mm), and each layer of the heating blanket should have a specific thermal resistance, based on the expected external conditions during use and the requirements of the heating system (i.e. requirements regarding energy consumption/efficiency and capacity to effectively regulate body exchanges with surrounding environment). The heating system should operate in an ON/OFF mode based on the body heating needs and within a temperature range specified based on the blanket total thermal resistance, external temperature during use, and observed temperature on the blanket outer surface (safety and energy efficiency aspects).The approach described in this work enabled the definition of the textile properties, the features of the embedded heating system, and the overall design of the system thus reducing substantially the number of prototypes needed for the final performance optimisation and fine-tuning.

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

“…This is becoming more relevant as the complexity of clothing systems increases (e.g. with integration of active heating/cooling elements, embedment of inflatable elements to alter local thermal properties; Couto et al 2011;Zhao et al 2013;Scott 2005;Neiva et al 2011;Neves et al 2014Neves et al , 2015b.…”

An experiment to assess the heat transfer performance of thermoelectric-driven conditioned mattress

“…In terms of the thermoregulation, the current focus has moved to mattress manipulation [11][12], regarded as a much more efficient approach. A number of strategies have been proposed including an electric heat blanket, or electrically heated sleeping bag [13][14]. These powered temperaturecontrolled facilities may meet the human thermal requirements within the bed microclimate, but they are to some extent dangerous owing to the direct contact with the human body.…”

Fabrication and thermal assessment of three-layer woven heating fabrics

“…11 Wang et al (2013) utilized an arc ion plating method for deposition at low temperature to produce carbon-based coatings on a glass fiber fabric in order to be used in a flexible heating fabric. 12 Neves et al (2015) performed a numerical study to investigate the heat transport through a blanket with an embedded smart heating system with regards to the impacts of thickness and thermal conductivity of the blanket, the position of heating wires relative to the skin, the distance between heating wires, applied heating power, and temperature range for operation of the heating system. 13 Yen et al (2015) studied the cold protective performance of electrically heated and chemically heated garments in cold environments using a Newton manikin operating in constant temperature mode.…”

“…12 Neves et al (2015) performed a numerical study to investigate the heat transport through a blanket with an embedded smart heating system with regards to the impacts of thickness and thermal conductivity of the blanket, the position of heating wires relative to the skin, the distance between heating wires, applied heating power, and temperature range for operation of the heating system. 13 Yen et al (2015) studied the cold protective performance of electrically heated and chemically heated garments in cold environments using a Newton manikin operating in constant temperature mode. 14 Roh and Kim (2016) fabricated a temperature sensing and heating textile by using metal composite embroidery yarn for the consistent maintenance of a definite targeted temperature by considering the human optimum thermal comfort in daily wear irrespective of the inner microclimate and outer climate circumstances.…”