Heat transfer characteristics of superheated steam combined with far infrared heating

The heat transfer characteristics of superheated steam (SHS) combined with far infrared heating (FIH) by a ceramic heater were compared with those of SHS and FIH performed separately. The heat transfer rate was evaluated from the drying rate of the water for each heating mode under the prescribed conditions. The heat transfer rate in SHS alone could be estimated well from semi-theoretical equations, which use an established empirical equation for the convective heat transfer coefficient. But the estimated values of the heat transfer rate in FIH were slightly smaller than the observed values. This indicates that the natural convective heat transfer rate should be slightly larger than that calculated using the empirical equation. FIH greatly enhanced the heat transfer rate of SHS. Further, some SHS stagnated in the vicinity of the ceramic heater and consequently was heated to a higher temperature, enabling additional radiative heat transfer. The effect of FIH on the heat transfer rate increased as the temperature difference between the ceramic heater and the SHS increased.