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 mm24 °C-4 °CQ̇ = ?

A wall of glass is 250 mm thick and has an area of 15 m². Its faces are held at 24 °C and -4 °C. Find the rate of heat conduction Q̇ through the wall.

k = 0.96 W/(m·K)L = 250 mmA = 15 m²T1 = 24 °CT2 = -4 °C
Q̇ = W
2.Easy
Concrete, k = 1.4250 mm16 °C4 °CQ̇ = ?

A wall of concrete is 250 mm thick and has an area of 6 m². Its faces are held at 16 °C and 4 °C. Find the rate of heat conduction Q̇ through the wall.

k = 1.4 W/(m·K)L = 250 mmA = 6 m²T1 = 16 °CT2 = 4 °C
Q̇ = W
3.Medium
Wood, k = 0.17100 mmGlass, k = 0.96100 mm17 °C2 °CTi​ = ?Q̇

A wall is made of 100 mm of wood and 100 mm of glass, with an area of 20 m². The outer faces are at 17 °C and 2 °C. Find the temperature Ti at the interface between the two layers.

L1 = 100 mm, k1 = 0.17 W/(m·K)L2 = 100 mm, k2 = 0.96 W/(m·K)A = 20 m²T1 = 17 °CT3 = 2 °C
Ti = °C
4.Medium
Mineral wool, k = 0.04250 mmWood, k = 0.1750 mm15 °C-13 °CQ̇ = ?

A wall is made of 250 mm of mineral wool and 50 mm of wood, with an area of 10 m². The outer faces are at 15 °C and -13 °C. Find the heat flow Q̇ through the wall.

L1 = 250 mm, k1 = 0.04 W/(m·K)L2 = 50 mm, k2 = 0.17 W/(m·K)A = 10 m²T1 = 15 °CT3 = -13 °C
Q̇ = W
5.Hard
Brick, k = 0.7250 mmMineral wool, k = 0.0425 mmroom 22 °Coutside -2 °CTs​ = ?Q̇

A wall of 50 mm brick and 25 mm mineral wool separates a room at 22 °C from outside air at -2 °C. The convection coefficients are 10 W/(m²·K) inside and 25 W/(m²·K) outside, and the wall area is 8 m². Find the temperature Ts of the inside surface of the wall.

L1 = 50 mm, k1 = 0.72 W/(m·K)L2 = 25 mm, k2 = 0.04 W/(m·K)A = 8 m²hi = 10 W/(m²·K)ho = 25 W/(m²·K)Troom = 22 °CTout = -2 °C
Ts = °C
6.Hard
Wood, k = 0.17100 mmExpanded polystyrene, k = 0.03575 mmroom 21 °Coutside 3 °CTs​ = ?Q̇

A wall of 100 mm wood and 75 mm expanded polystyrene separates a room at 21 °C from outside air at 3 °C. The convection coefficients are 6 W/(m²·K) inside and 20 W/(m²·K) outside, and the wall area is 12 m². Find the temperature Ts of the inside surface of the wall.

L1 = 100 mm, k1 = 0.17 W/(m·K)L2 = 75 mm, k2 = 0.035 W/(m·K)A = 12 m²hi = 6 W/(m²·K)ho = 20 W/(m²·K)Troom = 21 °CTout = 3 °C
Ts = °C

Answer key

  1. 1. Q̇ = 1613 W
  2. 2. Q̇ = 403.2 W
  3. 3. Ti = 4.257 °C
  4. 4. Q̇ = 42.79 W
  5. 5. Ts = 19.12 °C
  6. 6. Ts = 19.98 °C

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