An 18^'-tall facility having the dimensions 250^'×100^' has eight 4^'×8^' double-pane glass windows and two 3^'×8^' glass doors on both the front and back sides. The facility is made of 8^'' solid cinder block and a 1^" metal insulated roof with an insulated ceiling and an uninsulated slab floor.

Question

An [latex]18^{'}[/latex] -tall facility having the dimensions [latex]250^{'} imes 100^{'} [/latex] has eight [latex]4^{'} imes 8^{'} [/latex] double-pane glass windows and two [latex]3^{'} imes 8^{'} [/latex] glass doors on both the front and back sides. The facility is made of [latex]8^{''}[/latex] solid cinder block and a [latex]1^{''}[/latex]metal insulated roof with an insulated ceiling and an uninsulated slab floor. The facility is located in Chicago, Illinois. What is the heat loss?

Accepted Answer

The following data needed to calculate the heat loss may be obtained from a variety of sources [9].

[latex]U_{F} =0.81 Btu/(hr)(ft^{2})(°F) [/latex] [latex] t_{i}=70^{\circ } F[/latex]

[latex]U_{R} =0.20 Btu/(hr)(ft^{2})(°F) [/latex] [latex] t_{0}=0^{\circ } F[/latex]

[latex]U_{G} =0.63 Btu/(hr)(ft^{2})(°F) [/latex]

[latex]U_{D} =0.13 Btu/(hr)(ft^{2})(°F) [/latex]

[latex]U_{W} =0.39 Btu/(hr)(ft^{2})(°F) [/latex]

[latex]U_{I} =0.20 Btu/(hr)(ft^{2})(°F) [/latex]

Then, using Equation 9.2,

[latex]Q_{F} =(25,000ft^{2})\left[0.81 Btu/(hr)(ft^{2})(°F) ight](70°F-0°F) [/latex]
[latex]Q_{F} =14.175 imes 10^{5} Btu/hr[/latex]

[latex]Q_{R} =(25,000ft^{2})\left[0.20 Btu/(hr)(ft^{2})(°F) ight](70°F-0°F) [/latex]
[latex]Q_{R} =3.5 imes 10^{5} Btu/hr[/latex]

[latex]Q_{G} =(16)(32ft^{2})\left[0.63 Btu/(hr)(ft^{2})(°F) ight](70°F-0°F) [/latex]
[latex]Q_{G} =0.226 imes 10^{5} Btu/hr[/latex]

[latex]Q_{D} =(4)(24ft^{2})\left[1.13 Btu/(hr)(ft^{2})(°F) ight](70°F-0°F) [/latex]
[latex]Q_{D} =0.076 imes 10^{5} Btu/hr[/latex]

[latex]Q_{W} =\left[(2)(4500ft^{2})+(2)(1800ft^{2})-(16)(32ft^{2})-(4)(24ft^{2}) ight] \left[(0.39 Btu/(hr)(ft^{2})(°F) ight][/latex]
[latex](70^{\circ }F-0^{\circ }F)[/latex]

[latex]Q_{W} =3.274 imes 10^{5} Btu/hr[/latex]

[latex]Q_{I} =\left[(25,000ft^{2})+(12,600ft^{2}) ight] \left[(0.20 Btu/(hr)(ft^{2})(°F) ight](70^{\circ }F-0^{\circ }F)[/latex]

[latex]Q_{I} =0.526 imes 10^{5} Btu/hr[/latex]

Then, using Equation 9.1, the total heat loss may be calculated as follows:

[latex]Q_{H} =14.175 imes 10^{5} Btu/hr+3.5 imes 10^{5} Btu/hr+0.226 imes 10^{5} Btu/hr+0.076 imes 10^{5} Btu/hr+3.274 imes 10^{5} Btu/hr+0.526 imes 10^{5} Btu/hr[/latex]

[latex]Q_{H}=21.777 imes 10^{5} Btu/hr[/latex]

Question 9.2: An 18^'-tall facility having the dimensions 250^'×100^' has ...

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