Investigation of Microclimate Ventilation of Simulated Garment in Terms of Wind Speed and Air Gap Thickness

Abstract

During the circulation of air in the garment’s microclimate, the body extra heat dissipates to the environment. This event is an important factor in thermal comfort and ventilation. In this study, a heating cylinder was designed and calibrated to assess the ventilation occurrences in garment as a simulator of the human body. Tubular samples with different sizes were prepared using double jersey weft knitted fabric in order to obtain five levels of air gap thickness, including −1.5, 0, 1, 1.5 and 2 cm. Experiments were carried out in two conditions including without wind and by wind blowing with eight different wind speeds include 0.5, 1, 1.5, 2, 2.5, 3, 5 and 7 m/s. In each condition, the air gap’s temperature was considered as the main parameter for examination of the microclimate ventilation. The obtained outcomes revealed that by increasing the air gap thickness to more than 1 centimetre, the ventilation rate increased significantly. In the absence of wind, the change in the air gap’s temperature was not considerable for all sizes due to the natural convection phenomena that were slow. An increase of wind speed to more than 1 m/s led to a rise in the forced convection heat loss and took less time for the system to reach the equilibrium temperature; hence, higher ventilation rate was achieved. Moreover, by the increment of wind speed, the reduction of microclimate temperature follows a power function and at higher wind speeds remained approximately constant. According to the statistical analysis of results, it was confirmed that the ventilation rate of garment was influenced by wind speed; however, the influence of air gap thickness only in the absence of wind is significant.