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
Expanded polystyrene, k = 0.03520 mm23 °C8 °CQ̇ = ?

A wall of expanded polystyrene is 20 mm thick and has an area of 20 m². Its faces are held at 23 °C and 8 °C. Find the rate of heat conduction Q̇ through the wall.

k = 0.035 W/(m·K)L = 20 mmA = 20 m²T1 = 23 °CT2 = 8 °C
Q̇ = W
2.Easy
Expanded polystyrene, k = 0.03520 mm19 °C5 °Cq″ = ?

A wall of expanded polystyrene is 20 mm thick and has an area of 4 m². Its faces are held at 19 °C and 5 °C. Find the heat flux q″ through the wall.

k = 0.035 W/(m·K)L = 20 mmA = 4 m²T1 = 19 °CT2 = 5 °C
q″ = W/m²
3.Medium
Expanded polystyrene, k = 0.03550 mmWood, k = 0.1775 mm23 °C1 °CQ̇ = ?

A wall is made of 50 mm of expanded polystyrene and 75 mm of wood, with an area of 6 m². The outer faces are at 23 °C and 1 °C. Find the heat flow Q̇ through the wall.

L1 = 50 mm, k1 = 0.035 W/(m·K)L2 = 75 mm, k2 = 0.17 W/(m·K)A = 6 m²T1 = 23 °CT3 = 1 °C
Q̇ = W
4.Medium
Wood, k = 0.17150 mmConcrete, k = 1.475 mm15 °C-15 °CQ̇ = ?

A wall is made of 150 mm of wood and 75 mm of concrete, with an area of 10 m². The outer faces are at 15 °C and -15 °C. Find the heat flow Q̇ through the wall.

L1 = 150 mm, k1 = 0.17 W/(m·K)L2 = 75 mm, k2 = 1.4 W/(m·K)A = 10 m²T1 = 15 °CT3 = -15 °C
Q̇ = W
5.Hard
Brick, k = 0.72250 mmMineral wool, k = 0.0450 mmroom 20 °Coutside 5 °CQ̇ = ?

A wall of 250 mm brick and 50 mm mineral wool separates a room at 20 °C from outside air at 5 °C. The convection coefficients are 6 W/(m²·K) inside and 20 W/(m²·K) outside, and the wall area is 15 m². Find the heat loss Q̇ through the wall.

L1 = 250 mm, k1 = 0.72 W/(m·K)L2 = 50 mm, k2 = 0.04 W/(m·K)A = 15 m²hi = 6 W/(m²·K)ho = 20 W/(m²·K)Troom = 20 °CTout = 5 °C
Q̇ = W
6.Hard
Wood, k = 0.17150 mmExpanded polystyrene, k = 0.03575 mmroom 20 °Coutside -8 °CQ̇

A wall of 150 mm wood and 75 mm expanded polystyrene separates a room at 20 °C from outside air at -8 °C. The convection coefficients are 8 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 = 150 mm, k1 = 0.17 W/(m·K)L2 = 75 mm, k2 = 0.035 W/(m·K)A = 6 m²hi = 8 W/(m²·K)ho = 20 W/(m²·K)Troom = 20 °CTout = -8 °C
U = W/(m²·K)

Answer key

  1. 1. Q̇ = 525 W
  2. 2. q″ = 24.5 W/m²
  3. 3. Q̇ = 70.6 W
  4. 4. Q̇ = 320.5 W
  5. 5. Q̇ = 124 W
  6. 6. U = 0.3125 W/(m²·K)

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