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An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expression
h = 1.5(ΔT)0.33 W/m2- K
- a)11.0
- b)11.0
Correct answer is option ''. Can you explain this answer?
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An industrial furnace employs a hollow brick lining. The inside and o...
Heat lost by outer surface of the lining to surroundings per unit area,
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q = εσ(T24 - Tထ4)
q = 0.85 x 5.67 10-8[4304 - 3004]+1.5(430 -300)0.33 x (430 - 300)
q = 1257.3116 + 971.932
q = 2229.24 W
n-shields
∴ Heat transfer from surface 1 to 2 through n-shields must be equal to ̇q
⇒ 2229.24 = 
⇒ n+1 = 11.7
⇒ n = 10.7
⇒ n ≅ 11
Question_type 5
Most Upvoted Answer
An industrial furnace employs a hollow brick lining. The inside and o...
To calculate the number of shields needed, we first need to determine the rate of heat transfer through the furnace lining. This can be done by considering the heat transfer by radiation and natural convection.
Heat transfer by radiation:
The rate of heat transfer by radiation can be determined using the Stefan-Boltzmann Law. The equation is given by:
Q_rad = εσA(T1^4 - T2^4)
Where:
Q_rad = rate of heat transfer by radiation
ε = emissivity of the walls and shields
σ = Stefan-Boltzmann constant (5.67 x 10^-8 W/m^2K^4)
A = surface area of the furnace lining
T1 = temperature of the inside surface of the furnace lining (900 K)
T2 = temperature of the outside surface of the furnace lining (430 K)
Heat transfer by natural convection:
The rate of heat transfer by natural convection can be determined using the convective heat transfer coefficient. The equation is given by:
Q_conv = hA(T1 - T2)
Where:
Q_conv = rate of heat transfer by natural convection
h = convective heat transfer coefficient
A = surface area of the furnace lining
T1 = temperature of the inside surface of the furnace lining (900 K)
T2 = temperature of the outside surface of the furnace lining (430 K)
Total heat transfer:
The total rate of heat transfer through the furnace lining is the sum of the heat transfer by radiation and natural convection:
Q_total = Q_rad + Q_conv
Number of shields:
To calculate the number of shields needed, we divide the total rate of heat transfer by the rate of heat transfer through a single shield. The rate of heat transfer through a single shield can be determined using the same equations as above, but with the temperature difference between the shield surfaces and the surrounding temperature (300 K).
Let's assume the surface area of the furnace lining is A and the surface area of a single shield is S.
The rate of heat transfer through a single shield by radiation is given by:
Q_rad_shield = εσS(T_shield^4 - T_surrounding^4)
The rate of heat transfer through a single shield by natural convection is given by:
Q_conv_shield = hS(T_shield - T_surrounding)
The total rate of heat transfer through a single shield is the sum of the heat transfer by radiation and natural convection:
Q_total_shield = Q_rad_shield + Q_conv_shield
The number of shields needed can be calculated by dividing the total rate of heat transfer through the furnace lining by the total rate of heat transfer through a single shield:
Number of shields = Q_total / Q_total_shield
By substituting the values into the equations and calculating, we can determine the number of shields needed.
Heat transfer by radiation:
The rate of heat transfer by radiation can be determined using the Stefan-Boltzmann Law. The equation is given by:
Q_rad = εσA(T1^4 - T2^4)
Where:
Q_rad = rate of heat transfer by radiation
ε = emissivity of the walls and shields
σ = Stefan-Boltzmann constant (5.67 x 10^-8 W/m^2K^4)
A = surface area of the furnace lining
T1 = temperature of the inside surface of the furnace lining (900 K)
T2 = temperature of the outside surface of the furnace lining (430 K)
Heat transfer by natural convection:
The rate of heat transfer by natural convection can be determined using the convective heat transfer coefficient. The equation is given by:
Q_conv = hA(T1 - T2)
Where:
Q_conv = rate of heat transfer by natural convection
h = convective heat transfer coefficient
A = surface area of the furnace lining
T1 = temperature of the inside surface of the furnace lining (900 K)
T2 = temperature of the outside surface of the furnace lining (430 K)
Total heat transfer:
The total rate of heat transfer through the furnace lining is the sum of the heat transfer by radiation and natural convection:
Q_total = Q_rad + Q_conv
Number of shields:
To calculate the number of shields needed, we divide the total rate of heat transfer by the rate of heat transfer through a single shield. The rate of heat transfer through a single shield can be determined using the same equations as above, but with the temperature difference between the shield surfaces and the surrounding temperature (300 K).
Let's assume the surface area of the furnace lining is A and the surface area of a single shield is S.
The rate of heat transfer through a single shield by radiation is given by:
Q_rad_shield = εσS(T_shield^4 - T_surrounding^4)
The rate of heat transfer through a single shield by natural convection is given by:
Q_conv_shield = hS(T_shield - T_surrounding)
The total rate of heat transfer through a single shield is the sum of the heat transfer by radiation and natural convection:
Q_total_shield = Q_rad_shield + Q_conv_shield
The number of shields needed can be calculated by dividing the total rate of heat transfer through the furnace lining by the total rate of heat transfer through a single shield:
Number of shields = Q_total / Q_total_shield
By substituting the values into the equations and calculating, we can determine the number of shields needed.
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Community Answer
An industrial furnace employs a hollow brick lining. The inside and o...
Heat lost by outer surface of the lining to surroundings per unit area,
q = εσ(T24 - Tထ4)
q = 0.85 x 5.67 10-8[4304 - 3004]+1.5(430 -300)0.33 x (430 - 300)
q = 1257.3116 + 971.932
q = 2229.24 W
n-shields
∴ Heat transfer from surface 1 to 2 through n-shields must be equal to ̇q
⇒ 2229.24 = 
⇒ n+1 = 11.7
⇒ n = 10.7
⇒ n ≅ 11
Question_type 5
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An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer?
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An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer? for Chemical Engineering 2024 is part of Chemical Engineering preparation. The Question and answers have been prepared according to the Chemical Engineering exam syllabus. Information about An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer? covers all topics & solutions for Chemical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer?.
An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer? for Chemical Engineering 2024 is part of Chemical Engineering preparation. The Question and answers have been prepared according to the Chemical Engineering exam syllabus. Information about An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer? covers all topics & solutions for Chemical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer?.
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An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer?, a detailed solution for An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer? has been provided alongside types of An industrial furnace employs a hollow brick lining. The inside and outside surfaces of the hollow brick lining are maintained at 900 K and 430 K by placing radiation shields in between the hollow space. The heat loss occurs to the surroundings (300 K) by both radiation and natural convection. Calculate number of shields needed. The emissivity of walls and shields can be taken as 0.85. The convective heat transfer coefficient is governed by the expressionh = 1.5(ΔT)0.33 W/m2- Ka) 11.0b) 11.0Correct answer is option ''. Can you explain this answer? theory, EduRev gives you an
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