An architect is asked to determine the heat loss through a wall of a building constructed as shown in the sketch. If the wall spacing is 10 cm, the inner surface is at 20°C and the outer surface is at – 8°C with air between,

(a) Estimate the heat loss by natural convection. Then determine the effect of placing a baffle

(b) Horizontally at the midheight of the vertical section (B),

(c) Vertically at the center of the horizontal section (C), and

(d) Vertically half-way between the two surfaces (D).

GIVEN

Air filled wall construction as shown above

Inner wall temperature (Ti) = 20°C

Outer wall temperature (To) = – 8°C

Wall spacing (w) = 6 m

ASSUMPTIONS

• Wall temperatures are constant and uniform
• Steady state conditions
• Baffle thickness is negligible

Transcribed Image Text:

0.1 m Baffle (d) Outslde Baffle (c)- Baffle (b) Inside. 6 m