1.
Consider a 1.8m high and 1.5 mwide doublepane window consisting of two 4mm thick layers of glass (k = 0.78 W/m°C) separated by a 10mm wide stagnant air space (k = 0.026 W/m°C). The room is maintained at 20°C while the temperature of the outdoors is 10°C. Take the convective heat transfer coefficients on the inner and outer surfaces of the window to be 10 W/m2°C and 40 W/m2°C, respectively.
Determine the steady rate of heat transfer through this doublepane window?
A. 
155.8 W 

B. 
210.1 W 

C. 
346.9 W 

D. 
400.1 W 
2.
A glass window measures 1 m x 2 m x 0.5 cm thick. The temperature on one side of the window is 10°C,
while the temperature on the opposite side is 2°C. The thermal conductivity of the glass is 0.78 W/m K.
Find the amount of heat loss through the window after 5 hours. Provide answer in J/s
3.
Compute the log mean temperature difference for a heat exchanger with the hot fluid entering at 150°C and leaving at 90°C. The cold fluid enters at 20°C and leaves at 110°C.
Assume countercurrent flow.
A. 
25.3°C 

B. 
33.3°C 

C. 
53.6°C 

D. 
77.3°C 
4.
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