On the performance of a mitt heating multilayer: a numerical study

Couto, Sandra M.; Campos, J.B.L.M.; Mayor, Tiago Sotto

doi:10.1108/09556221111166301

Cited by 9 publications

(13 citation statements)

References 16 publications

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“…5a and b, respectively). This dependency is consistent with results reported in literature [17,31], though, in addition to previous works, the approach implemented in this work also takes into account the coupling between heat and mass transfer along the clothing structure. For instance, at the end of the exercise and post-exercise phases (phase I and II, Fig.…”

Section: Influence Of Several Parameters/characteristic Of Multilayersupporting

confidence: 82%

“…As in experimental procedures, the skin boundary conditions of heat and of mass are often set constant in numerical studies of heat and mass transfer through clothing [15][16][17][18][19][20][21][22][23][24]. Neves et al [15] studied the thermal performance of multilayer clothing assuming constant temperature and sweat rate on the skin, whereas Wu and Fan [18] defined the mass boundary condition as the concentration of water saturation, when studying a multilayer assembly exposed to a cold ambient.…”

Section: Introductionmentioning

confidence: 99%

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Effects of clothing and fibres properties on the heat and mass transport, for different body heat/sweat releases

Neves

Campos

Mayor

2017

Applied Thermal Engineering

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Section: Influence Of Several Parameters/characteristic Of Multilayersupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Effects of clothing and fibres properties on the heat and mass transport, for different body heat/sweat releases

Neves

Campos

Mayor

2017

Applied Thermal Engineering

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“…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.…”

Section: Introductionmentioning

confidence: 98%

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

et al. 2015

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The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s(-1)) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 10(2)-3 × 10(5)). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow patterns and temperature fields in the microclimates were found to strongly depend on the characteristics of the external boundary layer forming along the clothing and on the distribution of temperature in the clothing. The local heat transfer rates obtained in the microclimate are in marked contrast with those found in the literature for enclosures with constant-temperature active walls. These results stress the importance of coupling the calculation of the internal and the external flows and of the heat transfer convective and radiative components, when analyzing the way heat is transported to/from the body.

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“…Kocbach et al [14] used a finite element approach to evaluate the effect of several properties of a thermal stimulation equipment on the electrical stimulation of muscles. Couto et al [13] used an identical approach to enhance the thermal performance of an electrical-heated mitt. Other models have been developed concerning how a particular combination of textile properties affects the body heat loss [15,16], the water distribution inside clothing [17], the wind chill effect [18e21], and how the geometric features of the microclimates inside clothing affect the transport rates from the body [22e25].…”

Section: Introductionmentioning

confidence: 99%

“…This discomfort is especially felt when environmental conditions are substantially different from those for which the operating power of the heating system was specified. To overcome this constraint, the heating system can be adjustable and controlled based on the ambient or heating wire temperature, as reported by Couto et al [13].…”

Section: Introductionmentioning

confidence: 99%

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

Neves

Couto

Campos

et al. 2015

Applied Thermal Engineering

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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.

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On the performance of a mitt heating multilayer: a numerical study

Cited by 9 publications

References 16 publications

Effects of clothing and fibres properties on the heat and mass transport, for different body heat/sweat releases

Effects of clothing and fibres properties on the heat and mass transport, for different body heat/sweat releases

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

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

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