The rear window of a car is defrosted by having a transparent film heater attached to the glass. The heater provides a uniform heat flux on the surface that depends on the amount of current passing...

The rear window of a car is defrosted by having a transparent film heater attached to the glass. The heater provides a uniform heat flux on the surface that depends on the amount of current passing through it. If the window itself is 3 mm thick, the inner surface must be kept at 15°C for defrosting, and the interior and exterior conditions are Ti = 20°C hi = 10 W/m2K and To = –17°C, ho = 25 W/m2K:

a. What is the temperature profile through the glass?

b. How much power is required to hold the conditions constant per unit area of glass?

c. If the glass started out at the outside temperature of To, its density is 2500 kg/m3 and heat capacity of 750 J/kgK, how much has the glass’s internal energy per unit area changed?