Chapter 2 (Conduction)

What alphabet represent the plate thickness associated with the heat transfer rate, Q?

• L

• A

• H

• Q

A 10m high, 6m wide, and 0.5m thick brick wall has thermal conductivity of k = 0.8 W/m·°C. On a certain day, the temperatures of the inner and the outer surfaces of the wall are measured to be 14°C and 6°C, respectively. Calculate rate of heat loss through the wall on that day.

• 699 W

• 789 W

• 777 W

• 768 W

What is this formula?

• Thermal resistance

• Conduction

• Convection

• Thermal Energy

Series or Parallel or Combination thermal resistance network?

• Series

• Parallel

• Combination

What formula is this?

• Parallel thermal resistance

• Series thermal resistance

A 0.8m high and 1.5m wide glass window has thickness of 8cm and thermal conductivity k = 0.78 W/m·°C. Determine the steady rate of heat transfer through this glass window if the temperature of inner side is maintained at 20°C while the temperature of the outdoors is -10°C. Take the Rconvection inner  and Rconvection outer  of the window to be 0.0833 °C/W and 0.12 °C/W.

• 103 W

• 200 W

• 324 W

• 26 W

Answer explanation

Using thermal resistance concept for the calculation

A rectangular window has dimensions 2m high, 1.5m wide, and a thickness of 0.1m. The window is made of glass with a thermal conductivity of k = 0.8 W/m·°C. The indoor and outdoor temperatures are 20°C and -5°C, respectively. Calculate the rate of heat loss .

• 750 W

• 300 W

• 522 W

• 600 W