Development of a sweating fabric manikin with sedentary and supine postures

Abstract

Since the world first thermal manikin introduced in 1940s, thermal manikins have been widely used in research and development for more than 60 years. They have been proven to be useful tools for the measurement of clothing thermal insulation and evaporative resistance - essential parameters for evaluating the thermal comfort of clothing and environment. In this research, a novel sweating fabric manikin system, which can be adjusted to sedentary and supine postures, was developed for thermal comfort evaluation through the objective measurement of thermal insulation and evaporative resistance of clothing. The posture adjustment from sedentary to supine was achieved by interchanging the breathable fabric skin. A novel sweating rate measurement system was specially developed for the manikin to have real time sweating rate measurement. With this new manikin, high measurement accuracy is achieved at a relatively low cost in comparison with those existing manikins in Finland, Switzerland or USA. Two sets of experiments were conducted using the novel sedentary and supine manikin. In the first set of experiments, eleven sleeping bags were tested in terms of thermal insulation and evaporative resistance. The second set of experiments measured and compared the thermal insulation and evaporative resistance of seven clothing ensembles in standing, sedentary and standing posture. Both experiments demonstrated high reproducibility and consistency. For the testing of the thermal insulation of sleeping bags, standard test methods and procedures using heated manikins are provided in ASTM F1720-06 and EN 13537:2002. The testing protocol in this research followed ASTM F1720-06, except that there was no mattress, face mask and underwear. For the testing of evaporative resistance of sleeping bags, since no standard test method or procedure has so far been established, a test protocol was developed in this research. The tests for directly measuring the evaporative resistance of sleeping bags were carried out under the isothermal condition, viz. both the mean skin temperature of the manikin and that of the environment were controlled to be the same at 35 °C, with the wind speed and ambient relative humidity at 0.3 m s ⁻¹ and 50%, respectively. The results showed that the novel supine sweating fabric manikin is reproducible and accurate in directly measuring the evaporative resistance of sleeping bags. The measured evaporative resistance can be combined with the thermal insulation to calculate the moisture permeability index of sleeping bags. Evaporative resistance and thermal insulation of clothing are important parameters in the design and engineering of thermal environments and functional clothing. Past work on the measurement of evaporative resistance of clothing was however limited to the standing posture with or without body motion. Evaporative resistance of clothing when the wearer is at sedentary or supine posture and how it is related to that when the wearer is at standing posture are lacking. This research presents original data on the effect of postures on the evaporative resistance of clothing, thermal insulation and permeability index, based on the measurements under three postures, viz. sedentary, supine, and standing. Regression models are also established to predict the evaporative resistance and thermal insulation index of clothing under sedentary and supine postures from those under standing posture with high accuracy.