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2. The defog dial in an automobile causes warm air to pass over the inside surface of the front windshield resulting in heat transfer from the inside (T = 40

°C) with a convective heat transfer coefficient of 35 W/m²-K to the outside on a cold day. The windshield is made of plate glass and has a thickness of 0.50 cm, and the outside air is -10 °C with a convective heat transfer coefficient of 75 W/m²-K. Ignore radiation in this problem. You may use glass properties at 300 K, assume k is constant and that the heat transfer is at steady state. A. Calculate the total thermal resistance of the air-window-air system, R", and the heat flux, q", across the window. B. Determine the inner and outer surface temperatures of the windshield. C. The convective heat transfer coefficient is a function of fluid velocity (and Reynolds number); thus h increases as you drive faster. For an outside convective heat transfer coefficient of ho = 120 W/m²-K (no changes to other variables), determine the surface temperatures inside and outside the windshield as well as the heat flux. D. In the rear window of some cars, you'l| see imbedded electrical wires that provide heat to help with de-icing in wintry weather. What term in the heat diffusion equation would you use to represent this type of heating? E. For the situation in part D, draw a qualitative T-x plot, starting with the air inside the car, and going across the window to a bulk winter air temperature on the outside. Assume the wire is in the center of the glass.

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