Chapter:

Transient-(Unsteady-State-Heat-Conduction)

The following data pertains to junction of a rmocouple wire used to measure temperature of gas stream.
Density = 8500 kg/m3, specific heat = 325 J/kg K, rmal conductivity = 40 W/m K and heat transfer coefficient between junction and gas = 215 W/m2 K.
If rmocouple junction can be approximated as 1 mm diameter sphere, determine how long it will take for rmocouple to read 99% of initial temperature difference