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 = 0.96200 mm16 °C3 °Cq″ = ?

A wall of glass is 200 mm thick and has an area of 15 m². Its faces are held at 16 °C and 3 °C. Find the heat flux q″ through the wall.

k = 0.96 W/(m·K)L = 200 mmA = 15 m²T1 = 16 °CT2 = 3 °C
q″ = W/m²
2.Easy
Mineral wool, k = 0.04150 mm22 °C-8 °CQ̇ = ?

A wall of mineral wool is 150 mm thick and has an area of 12 m². Its faces are held at 22 °C and -8 °C. Find the rate of heat conduction Q̇ through the wall.

k = 0.04 W/(m·K)L = 150 mmA = 12 m²T1 = 22 °CT2 = -8 °C
Q̇ = W
3.Medium
Mineral wool, k = 0.04100 mmGlass, k = 0.9675 mm21 °C0 °CTi​ = ?Q̇

A wall is made of 100 mm of mineral wool and 75 mm of glass, with an area of 12 m². The outer faces are at 21 °C and 0 °C. Find the temperature Ti at the interface between the two layers.

L1 = 100 mm, k1 = 0.04 W/(m·K)L2 = 75 mm, k2 = 0.96 W/(m·K)A = 12 m²T1 = 21 °CT3 = 0 °C
Ti = °C
4.Medium
Expanded polystyrene, k = 0.03550 mmConcrete, k = 1.4100 mm16 °C-6 °CQ̇ = ?

A wall is made of 50 mm of expanded polystyrene and 100 mm of concrete, with an area of 15 m². The outer faces are at 16 °C and -6 °C. Find the heat flow Q̇ through the wall.

L1 = 50 mm, k1 = 0.035 W/(m·K)L2 = 100 mm, k2 = 1.4 W/(m·K)A = 15 m²T1 = 16 °CT3 = -6 °C
Q̇ = W
5.Hard
Glass, k = 0.96250 mmConcrete, k = 1.4100 mmroom 22 °Coutside 0 °CQ̇

A wall of 250 mm glass and 100 mm concrete separates a room at 22 °C from outside air at 0 °C. The convection coefficients are 6 W/(m²·K) inside and 25 W/(m²·K) outside, and the wall area is 20 m². Find the overall heat transfer coefficient U of the wall.

L1 = 250 mm, k1 = 0.96 W/(m·K)L2 = 100 mm, k2 = 1.4 W/(m·K)A = 20 m²hi = 6 W/(m²·K)ho = 25 W/(m²·K)Troom = 22 °CTout = 0 °C
U = W/(m²·K)
6.Hard
Concrete, k = 1.4250 mmWood, k = 0.1725 mmroom 22 °Coutside 2 °CQ̇

A wall of 250 mm concrete and 25 mm wood separates a room at 22 °C from outside air at 2 °C. The convection coefficients are 10 W/(m²·K) inside and 20 W/(m²·K) outside, and the wall area is 6 m². Find the overall heat transfer coefficient U of the wall.

L1 = 250 mm, k1 = 1.4 W/(m·K)L2 = 25 mm, k2 = 0.17 W/(m·K)A = 6 m²hi = 10 W/(m²·K)ho = 20 W/(m²·K)Troom = 22 °CTout = 2 °C
U = W/(m²·K)

Answer key

  1. 1. q″ = 62.4 W/m²
  2. 2. Q̇ = 96 W
  3. 3. Ti = 0.6364 °C
  4. 4. Q̇ = 220 W
  5. 5. U = 1.857 W/(m²·K)
  6. 6. U = 2.102 W/(m²·K)

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