A method for measuring a steam mole fraction at the temperature of around 80 - 300℃ and the steam mole fraction of hot air to superheated steam as the objects of heating devices for cooking, and so on, was considered in this study. The temperatures of spherical wet materials (brick and gauze) were measured in a flow system wherein the temperatures and humidity were regulated by heaters and by balancing the flow rate of steam and air, respectively. The steam mole fraction was calculated from the wet material temperatures by two methods, based on adiabatic saturated temperature and on heat and mass transfer model in boundary layer. These calculation results were in good agreement with the set values of the experimental flow conditions. The psychrometric chart for a wide temperature and humidity range including superheated steam was proposed as well. In addition, error factors of between the measured temperatures of wet material and the adiabatic saturated temperature were investigated.
