Consider a horizontal flat roof section having the same dimensions as a vertical wall section. For both sections, the surfaces exposed to the air gap are at 18°C (inside) and -10^oC (outside).

(a) Estimate the ratio of the convection heat rate for the horizontal section to that of the vertical section.

(b) What effect with inserting a baffle at the mid-height of the vertical section has on the convection heat rate for that section?

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Vertical wall section 0.1 m -3 m Horizontal roof section 3 m Baffle, part b Air 0.1 m