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
Concrete, k = 1.4100 mm21 °C-6 °CQ̇ = ?

A wall of concrete is 100 mm thick and has an area of 6 m². Its faces are held at 21 °C and -6 °C. Find the rate of heat conduction Q̇ through the wall.

k = 1.4 W/(m·K)L = 100 mmA = 6 m²T1 = 21 °CT2 = -6 °C
Q̇ = W
2.Easy
Wood, k = 0.17100 mm20 °C-1 °Cq″ = ?

A wall of wood is 100 mm thick and has an area of 10 m². Its faces are held at 20 °C and -1 °C. Find the heat flux q″ through the wall.

k = 0.17 W/(m·K)L = 100 mmA = 10 m²T1 = 20 °CT2 = -1 °C
q″ = W/m²
3.Medium
Expanded polystyrene, k = 0.035150 mmWood, k = 0.1725 mm25 °C2 °CQ̇ = ?

A wall is made of 150 mm of expanded polystyrene and 25 mm of wood, with an area of 20 m². The outer faces are at 25 °C and 2 °C. Find the heat flow Q̇ through the wall.

L1 = 150 mm, k1 = 0.035 W/(m·K)L2 = 25 mm, k2 = 0.17 W/(m·K)A = 20 m²T1 = 25 °CT3 = 2 °C
Q̇ = W
4.Medium
Mineral wool, k = 0.04250 mmBrick, k = 0.7275 mm23 °C2 °CQ̇ = ?

A wall is made of 250 mm of mineral wool and 75 mm of brick, with an area of 8 m². The outer faces are at 23 °C and 2 °C. Find the heat flow Q̇ through the wall.

L1 = 250 mm, k1 = 0.04 W/(m·K)L2 = 75 mm, k2 = 0.72 W/(m·K)A = 8 m²T1 = 23 °CT3 = 2 °C
Q̇ = W
5.Hard
Wood, k = 0.17250 mmGlass, k = 0.9650 mmroom 22 °Coutside -9 °CQ̇ = ?

A wall of 250 mm wood and 50 mm glass separates a room at 22 °C from outside air at -9 °C. The convection coefficients are 10 W/(m²·K) inside and 20 W/(m²·K) outside, and the wall area is 20 m². Find the heat loss Q̇ through the wall.

L1 = 250 mm, k1 = 0.17 W/(m·K)L2 = 50 mm, k2 = 0.96 W/(m·K)A = 20 m²hi = 10 W/(m²·K)ho = 20 W/(m²·K)Troom = 22 °CTout = -9 °C
Q̇ = W
6.Hard
Brick, k = 0.72150 mmExpanded polystyrene, k = 0.035100 mmroom 20 °Coutside -1 °CQ̇

A wall of 150 mm brick and 100 mm expanded polystyrene separates a room at 20 °C from outside air at -1 °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 overall heat transfer coefficient U of the wall.

L1 = 150 mm, k1 = 0.72 W/(m·K)L2 = 100 mm, k2 = 0.035 W/(m·K)A = 4 m²hi = 6 W/(m²·K)ho = 20 W/(m²·K)Troom = 20 °CTout = -1 °C
U = W/(m²·K)

Answer key

  1. 1. Q̇ = 2268 W
  2. 2. q″ = 35.7 W/m²
  3. 3. Q̇ = 103.8 W
  4. 4. Q̇ = 26.44 W
  5. 5. Q̇ = 370.7 W
  6. 6. U = 0.3047 W/(m²·K)

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