A thermopane window consists of two glass panes, each 0.50 cm thick, with a 1.0-

Question

A thermopane window consists of two glass panes, each 0.50 cm thick, with a 1.0-cm-thick sealed layer of air in between. (Use 0.8 J/s · m · °C for the thermal conductivity of glass and 0.0234 J/s · m · °C for the thermal conductivity of air to answer the following.)

(a) If the inside surface temperature is 23.6°C and the outside surface temperature is 0.0°C, determine the rate of energy transfer through 1.55 m2 of the window.
W

(b) Compare your answer to (a) with the rate of energy transfer through 1.55 m2 of a single 1.0-cm-thick pane of glass. Disregard surface air layers.
W

Explanation / Answer

heat transfer per sec = Q = A*dT / ( x1/k1 + x2/k2 + x3/k3 )

x1 = 0.005m

x2 = 0.01 m

x3 = 0.005 m

k1 = 0.8 J/s

k2 = 0.02234 J/s

k3 = 0.8 J/s

Q1 = (1.55*23.6)/( (0.005/0.8 + 0.01/0.0234 + 0.005/0.8))

Q1 = 83.16 J/s

-----------

b)

with single window

Q2 = A*dT/(x/k)

Q2 = (1.55*23.6)/(0.01/0.8) = 2926.4 J/s

Q2 > Q1

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.