Bhomit Pahilwani

Hi, as you can see I've taken a plain slab for the initial problem and assigned an external temperature along with a convective boundary condition on the edge of the slab with the varying temperature at different times. In the result, the slab maximum temperature doesn't go beyond 22.9 Celsius which shouldn't be the case.

Sorry for the jumbled pictures, I cannot arrange them properly.
Thank you.