A heating system is designed to keep the inner wall surfacetemperature of a room at

25ï‚°C. Only one wall of the room is contacted with the outerenvironment. The crosssectional view of the wall is schematicallyshown in Fig. H1. The height, width and

thickness of the wall are 2.5 m, 10 m and 0.2 m, respectively.The wall is made from red

bricks with a thermal conductivity of 0.72 W/m.K and solarabsorptivity of s = 0.63.

The temperature and velocity of the ambient air stream are 1ï‚°Cand 20 km/h,

respectively at the outside. In addition, solar irradiationcoming to the wall surface is

40 W/m2. Considering the given “day” conditions of winter,

a. Make an energy balance on the outer surface of the wall (showall input and output

streams). [3pts]

b. What is the outer surface temperature of the wall?[10pts]

c. What is the total heat loss from the wall? [2pts]

d. If an insulating material with a thickness of 3 cm and athermal conductivity of

0.05 W/m.K is mounted to the adjacent of the wall (from roomside), how is the outer

surface temperature and heat loss from the wall changed? Whateffect would such

an application have? [5pts]

e. How is the total heat loss from the wall with no insulationchanged if the wind speed

increases to Uï‚¥= 40 km/h at the outside environment. Determinethe percentage

increase/decrease in the heat loss, when compared to heat lossfound in (c.). [5pts]