Question

A cold storage room is used to keep the temperature inside the room maintain at low temperature.

Answer 1

Answer:

16 W

Explanation:

The sum of convective and conductive heat transfer through layers of walls can be modeled as:

Q = (T₂ − T₁) A / R

where Q is the rate of heat transfer,

T₂ − T₁ is the temperature difference,

and A is the cross sectional area.

R, the thermal resistance, is defined as:

R = ∑1/h + ∑L/k

where h is the convective heat transfer coefficient of the fluid,

L is the thickness of the wall,

and k is the thermal conductivity of the wall.

Given:

T₂ − T₁ = 35 K

A = 21 m²

h₁ = 11 W/m²/K

h₂ = 23 W/m²/K

For the polystyrene:

L₁ = 0.05 m

k₁ = 0.0011 W/m/K

For the cement:

L₂ = 0.02 m or 0.21 m

k₂ = 0.33 W/m/K

For the brick:

L₃ = 0.17 m

k₃ = 0.77 W/m/K

For the layer above and below the brick:

R = (1/11 + 1/23 + 0.05/0.0011 + 0.21/0.33)

R = 46.2 m²K/W

For the layer containing the brick:

R = (1/11 + 1/23 + 0.05/0.0011 + 0.02/0.33 + 0.17/0.77 + 0.02/0.33)

R = 45.9 m²K/W

So the average thermal resistance is:

R = (6/30) (46.2) + (24/30) (45.9)

R = 46.0 m²K/W

Therefore, the heat transfer through the wall is:

Q = (35 K) (21 m²) / (46.0 m²K/W)

Q = 16.0 W

Rounding to two significant figures, the rate of heat transfer through the wall is 16 W.

Answer 2

Answer:

The power of the brick wall it may be how the soiled ness of the wall too keep in the cold

Explanation: