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pishuonlain [190]

3 years ago

13

Find the number of Btu conducted through a wall in 8 hours. The wall is 8 feet high by 24 feet long and has a total R-value of 1

6.2 hr⋅°F⋅ft2 /Btu, including the effects of the inner and outer air layers. The inside temperature is 68°F and the outside temperature is 16°F.

1 answer:

dedylja [7]3 years ago

7 0

Answer:

ΔQ = 4930.37 BTu

Explanation:

given data

height h = 8ft

Δt = 8 hours

length L = 24 feet

R value = 16.2 hr⋅°F⋅ft² /Btu

inside temperature t1 = 68°F

outside temperature t2 = 16°F

to find out

number of Btu conducted

solution

we get here number of Btu conducted by this expression that s

$\frac{\Delta Q}{\Delta t} =\frac{-A}{R} (t2 -t1)$ ......................1

here A is area that is = h × L = 8 × 24 = 1492 ft²

put here value we get

$\frac{\Delta Q}{8} =\frac{-192}{16.2} (16-68)$

solve it we get

ΔQ = 4930.37 BTu

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Answer:

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$\Delta t_{mean} = \frac{1 + \sqrt{2} }{6000}\,h$

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