Problem HW4P2 A building has a wall constructed as ASHRAE Wall 12. The inside of the building is maintained at 22 °C and the outside is subjected to the sol-air temperature distribution given in the table below. a. b. C. Time (hr) 1 2 3 4 5 6 Tsa (°C) 21 21 20 19 19 18 Time (hr) 7 8 9 10 11 12 Tsa (°C) 19 20 22 24 31 35 Time (hr) 13 14 15 16 17 18 Tsa (°C) 37 39 39 38 37 35 Time (hr) 19 20 21 22 23 24 Tsa (°C) 32 29 27 24 22 22 Determine and plot the transient heat flux through the wall as a function of time of day assum- ing that there is no effect of thermal capacitance in the wall; i.e. the heat flux at any time is the product of the conductance and the temperature difference. Determine the heat flux through the wall as a function of time of day using the thermal net- work method. Superimpose the heat flux variation on the plot for part b. Draw some conclusions about the effect of capacitance on heat flux.

Fig: 1