An engineer who is working on the heat transfer analysis of a house in English units needs the convection heat transfer coefficient on the outer surface of the house. But the only value he can find from his handbooks is 14?W/m2•K, which is in SI units. The engineer does not have a direct conversion factor between the two unit systems for the convection heat transfer coefficient. Using the conversion factors between W and Btu/h, m and ft, and °C and °F, express the given convection heat transfer coefficient in Btu/h•ft2•°F.
What will be an ideal response?
Using the conversion factors between W and Btu/h, m and ft, and °C and °F, the convection coefficient in SI units is to be expressed in Btu/h•ft²•°F.
Analysis The conversion factors for W and m are straightforward, and are given in conversion tables to be
1 W = 3.41214Btu/h
1m = 3.2808ft
The proper conversion factor between °C into °F in this case is
1 °C = 1.8°F
since the °C in the unit W/m²•°C represents per °C change in temperature, and 1°C change in temperature corresponds to a change of 1.8°F. Substituting, we get
which is the desired conversion factor. Therefore, the given convection heat transfer coefficient in English units is
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