A thermopane window consists of two pieces of glass each 0.1" thick separated by a layer...

A thermopane window consists of two pieces of glass each 0.1" thick separated by a layer of dry,
stagnant air .4" thick.
• Find the resistance of a 4 ft × 3 ft thermopane window.
• Suppose the window is made by fastening an aluminum border .1" thick all around the edge.
Find the total resistance for this configuration.
• As an alternative to the aluminum, we might use a border of .75" thick white pine. Find the total
resistance for this configuration. (For white pine, "across the grain", k = .087 Btu/hr ft °F).
• Calculate the heat loss for the two windows and compare with that for a single pane of .1" glass.

Solutions

Expert Solution

Thermopane
Glass Thickness	0.1	0.00254	m
Air	0.4	0.01016	m
L	4	1.2192	m
B	3	0.9144	m
kg		0.869	W/mK
ka		0.026	W/mK
R1		0.002622
R2		0.350517
R3		0.002622
Total Resistance		0.355761	K/W
Aluminium Border
Glass Thickness	0.1	0.00254	m
Air	0.4	0.01016	m
L	4	1.21412	m
B	3	0.90932	m
kg		0.869	W/mK
ka		0.026	W/mK
kal		0.022
R1		0.002647
R2		0.350517
R3		0.002647
R4		0.103562	0.100914
Total Resistance		0.456726	K/W
White Pine Border
Glass Thickness	0.1	0.00254	m
Air	0.4	0.01016	m
L	4	1.20015	m
B	3	0.89535	m
kg		0.869	W/mK
ka		0.026	W/mK
kp		1.5047	W/mk
R1		0.00272
R2		0.350517
R3		0.00272
R4		0.001514	-0.00121
Total Resistance		0.358677	K/W
Single Pane
Glass Thickness	0.1	0.00254	m
Air	0.4	0.01016	m
L	4	1.2192	m
B	3	0.9144	m
kg		0.869
ka		0.026
R1		0.002622
R2		0.350517
R3
Total Resistance		0.353139	K/W
Temperature Diff		5	K
Single Pane Heat Loss		15.78467	W/m
Double Pane Heat Loss		15.66835	W/m

Amanda K answered 1 year ago

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