Tiago Sotto Mayor

Localised boundary air layer and clothing evaporative resistances for individual body segments

Evaporative resistance is an important parameter to characterise clothing thermal comfort. However, previous work has focused mainly on either total static or dynamic evaporative resistance. There is a lack of investigation of localised clothing evaporative resistance. The objective of this study was to study localised evaporative resistance using sweating thermal manikins. The individual and interaction effects of air and body movements on localised resultant evaporative resistance were examined in a strict protocol. The boundary air layers localised evaporative resistance was investigated on nude sweating manikins at three different air velocity levels (0.18, 0.48 and 0.78 m/s) and three different walking speeds (0, 0.96 and 1.17 m/s). Similarly, localised clothing evaporative resistance was measured on sweating manikins at three different air velocities (0.13, 0.48 and 0.70 m/s) and three walking speeds (0, 0.96 and 1.17 m/s). Results showed that the wind speed has distinct effects on local body segments. In contrast, walking speed brought much more effect on the limbs, such as thigh and forearm, than on body torso, such as back and waist. In addition, the combined effect of body and air movement on localised evaporative resistance demonstrated that the walking effect has more influence on the extremities than on the torso. Therefore, localised evaporative resistance values should be provided when reporting test results in order to clearly describe clothing local moisture transfer characteristics. Practitioner Summary: Localised boundary air layer and clothing evaporative resistances are essential data for clothing design and assessment of thermal comfort. A comprehensive understanding of the effects of air and body movement on localised evaporative resistance is also necessary by both textile and apparel researchers and industry.

Numerical simulation of the transport phenomena in tilted clothing microclimates

Humans depend on clothing protection to minimize the thermal burden imposed on the body by the surrounding environments to which they may be exposed ([1]). The ability of clothing to offer protection depends on multiple factors, from properties of its materials to geometrical aspects influencing the shape of the clothing elements and the way they fit the body. The latter is particularly relevant for the case of loose garments (e.g. CBRN), where relatively thick microclimates exist between the skin and the clothing, which may originate internal buoyancy-driven flows (i.e. natural convection) and substantially alter the way heat is transported to/from the body. Recent literature ([2-4]) report relevant changes in the local heat transport along the skin, in horizontal clothing microclimates, stressing the need for analyses of other geometrical arrangements occurring within clothing.

Thermal effects of headgear: state-of-the-art and way forward

Headgear is widely used in both work and leisure. Much research attention has been spent on optimizing impact properties of helmets [1], [2]. However, thermal comfort of headgear is suboptimal in neutral and warm environments. In fact, thermal discomfort is often given as a reason to not wear protective headgear [3], [4]. Enhanced thermal comfort of headgear is likely to improve the willingness to wear protective headgear, and motivated an increasing number of studies, of which most were published in the last decade. The available body of literature allows for a valuable first review on the thermal effects of headgear.

Freezing the Nonclassical Crystal Growth of a Coordination Polymer Using Controlled Dynamic Gradients.

A methodology that can be efficiently used to synthesize, isolate, and study out-of-equilibrium crystal structures employing controlled and diffusion-limited microfluidic environments is demonstrated. Unlike studies conducted with conventional mixing procedures in a flask, it is proven experimentally and with numerical simulations that microfluidic technologies can undoubtedly fine-tune reaction times and reagents concentration profiles; factors that enable out-of-equilibrium crystal forms to be obtained.

A 3D Printed Thermal Manikin Head for Evaluating Helmets for Convective and Radiative Heat Loss

Thermal performance of three bicycle helmets for radiative and convective heat loss was evaluated through heat loss experiments in a wind tunnel. A 3D printed thermal manikin head of a 50th percentile western male population was developed. Thermal performance of a helmet was quantified by comparing the manikin head heat losses with and without helmet. Experiments were performed for two air velocities: 1.6 m/s and 6 m/s. An infrared heat lamp positioned above the manikin simulated the effect of solar load. The results from the experiments showed a convective cooling efficiency between 89% and 96% for open helmets and between 78% and 83% for closed helmets. The radiative heat gain ranged from 3.5 W to 4.5 W for open helmets and 5 W to 8 W for closed helmets.