On the Some Infra Red Ray Drying Unita by means of a SiC Radiator (2nd Report)

Abstract

(1) The electric, radiant and heat transfer properties of the some commercial SiC heaters were investigated, and the most suitable conditions as a radiation source of infra-red ray drying were discussed in this report.(2) Electric resistance and radiant energy of the radiators were measured in the temperature'range 15°-1000°C. According to the experimerts, the values of radiation coefficient of the radiators were 4.9-5.08×10-12 and their emissivity calculated from them was 0.85-0.88.As shown by theory of semi-conductor, under a crit-ical temperature Tc (°K) specific conductivity σ(Ω-1 cm-1) of any sample was expressed by σ=σ0e-e/kT(3) Measuring the temperature difference between the surface and the central axis of the radiator by optical pyrometry, thermal conductivity K of the samples was calculated in the temperature range 700°C-1100°C. The values of K in this temperature range wefe 3-5×10-2 cal/cm2 sec deg.(4) The convection loss of the radiators fixed horizontally was Calculated by measurement of input power and radiant energy in the state of natural and forced convection. The convection loss was well expressed by the following equationsH=FK2 (T-T0) 5/4 (natural convection)H=FK3 (T-T0)(forced convection)(5) To solve the practically important question to decide the relation between the suitable electric and radiant characteristics of radiator and the crystallogiaphical structure of SiC and its impurities, a more detailed research would be necessary.