(35 points) On a winter day, the base of a single-pane window with height H=1.0m and width W= 0.75m has a layer of frost at its base. The bulk air temperature inside the room is T=20.0C. The inside of the room can be assumed to be a quiescent fluid. The air thermal expansion coefficient has an empirical correlation =1/Tfilm (in Kelvin). (a) Explain why the window would show a frost layer at the base rather than at the top. (b) At steady state, the interior surface of the window can be assumed to have a uniform temperature TS=0C. Using Appendix A.4, determine the fluid properties (,,cp,,v and kf) of the air at the appropriate reference temperature for convective heat transfer inside. (c) Calculate the Rayleigh number for this system. (d) From Table 9.2 (attached), find the appropriate Nu correlation for this system. (e) Determine the symbolic expression and the value of the average heat transfer coefficient h using the correlation. (f) Calculate the rate of heat transfer (q) from the window due to free convection. (g) If the room uses electric heating and has a utility rate of $0.14/kWh, how much will the monthly heating cost to compensate for heat loss through this one window? Appendix A = Themmophysical Properties of Matter 995 TaBIE A.4 Thermophysical Properties of Gases at Atmospheric Pressure Ammonia (NH3),M=17.03kg/kmol 3003203403603800.68940.64480.60590.57160.54102.1582.1702.1922.2212.254101.5109116.512413114.716.919.221.724.224.727.229.331.634.016.619.422.124.927.90.8870.8700.8720.8720.869