Heat conduction worksheet with answers

Free printable Heat conduction worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
Glass, k = 0.96250 mm25 °C-1 °CQ̇ = ?

A wall of glass is 250 mm thick and has an area of 10 m². Its faces are held at 25 °C and -1 °C. Find the rate of heat conduction Q̇ through the wall.

k = 0.96 W/(m·K)L = 250 mmA = 10 m²T1 = 25 °CT2 = -1 °C
Q̇ = W
2.Easy
Brick, k = 0.7210 mm20 °C-9 °CQ̇ = ?

A wall of brick is 10 mm thick and has an area of 4 m². Its faces are held at 20 °C and -9 °C. Find the rate of heat conduction Q̇ through the wall.

k = 0.72 W/(m·K)L = 10 mmA = 4 m²T1 = 20 °CT2 = -9 °C
Q̇ = W
3.Medium
Wood, k = 0.17100 mmGlass, k = 0.9650 mm19 °C2 °CQ̇ = ?

A wall is made of 100 mm of wood and 50 mm of glass, with an area of 20 m². The outer faces are at 19 °C and 2 °C. Find the heat flow Q̇ through the wall.

L1 = 100 mm, k1 = 0.17 W/(m·K)L2 = 50 mm, k2 = 0.96 W/(m·K)A = 20 m²T1 = 19 °CT3 = 2 °C
Q̇ = W
4.Medium
Brick, k = 0.72150 mmWood, k = 0.1775 mm17 °C6 °CTi​ = ?Q̇

A wall is made of 150 mm of brick and 75 mm of wood, with an area of 4 m². The outer faces are at 17 °C and 6 °C. Find the temperature Ti at the interface between the two layers.

L1 = 150 mm, k1 = 0.72 W/(m·K)L2 = 75 mm, k2 = 0.17 W/(m·K)A = 4 m²T1 = 17 °CT3 = 6 °C
Ti = °C
5.Hard
Wood, k = 0.17250 mmGlass, k = 0.96150 mmroom 22 °Coutside 2 °CTs​ = ?Q̇

A wall of 250 mm wood and 150 mm glass separates a room at 22 °C from outside air at 2 °C. The convection coefficients are 6 W/(m²·K) inside and 20 W/(m²·K) outside, and the wall area is 4 m². Find the temperature Ts of the inside surface of the wall.

L1 = 250 mm, k1 = 0.17 W/(m·K)L2 = 150 mm, k2 = 0.96 W/(m·K)A = 4 m²hi = 6 W/(m²·K)ho = 20 W/(m²·K)Troom = 22 °CTout = 2 °C
Ts = °C
6.Hard
Brick, k = 0.72200 mmMineral wool, k = 0.0425 mmroom 20 °Coutside -3 °CQ̇

A wall of 200 mm brick and 25 mm mineral wool separates a room at 20 °C from outside air at -3 °C. The convection coefficients are 8 W/(m²·K) inside and 25 W/(m²·K) outside, and the wall area is 8 m². Find the overall heat transfer coefficient U of the wall.

L1 = 200 mm, k1 = 0.72 W/(m·K)L2 = 25 mm, k2 = 0.04 W/(m·K)A = 8 m²hi = 8 W/(m²·K)ho = 25 W/(m²·K)Troom = 20 °CTout = -3 °C
U = W/(m²·K)

Answer key

  1. 1. Q̇ = 998.4 W
  2. 2. Q̇ = 8352 W
  3. 3. Q̇ = 531 W
  4. 4. Ti = 13.47 °C
  5. 5. Ts = 20.19 °C
  6. 6. U = 0.9365 W/(m²·K)

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