To defrost ice accumulated on the outer surface of an automobile windshield, warm air is blown over the inner surface of the windshield. Consider an automobile windshield with thickness of 5 mm and thermal conductivity of 1.4 W/m·K. The outside ambient temperature is 210°C and the convection heat transfer coefficient is 200 W/m²·K, while the ambient temperature inside the automobile is 25°C. Determine the value of the convection heat transfer coefficient for the warm air blowing over the inner surface of the windshield necessary to cause the accumulated ice to begin melting.

Transcribed Image Text:

Outside air, -10°C h, = 200 W/m²-K T₁ = 0°C L = 5 mm Windshield k = 1.4 W/m-K Inside air, 25°C