A thermocouple junction of spherical form is to be used to measure the temperature of the gas stream for which h = 400 W/m2K and k = 20 W/mK, C,, = 400 J/kg K, p = 8500 kg/m3. Find: (i) junction...

A thermocouple junction of spherical form is to be used to measure the temperature of the gas stream for which h = 400 W/m2K and k = 20 W/mK, C,, = 400 J/kg K, p = 8500 kg/m3. Find: (i) junction diameter needed for the thermocouple to have time constant of one second, (ii) time required for the thermocouple junction to reach 198°C if junction is initially at 25°C and is placed in a gas stream which is at 200°C.