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 -10°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.

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Heating element 4, = 1300 W/m? Inside alr, 22°C h, = 15 W/m2K Outside alr, -5°C h.- 100 W/m2-K Rear window k= 1.2 W/m-K L= 5 mm