Five Kilograms of continuous boron fibers are introduced in a unidirectional orientation into of an 8kg aluminum matrix. Calcula
1 answer:
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Answer:
a. 46.15%
b. 261.73 kg/s
c. 54.79 kW/K
Explanation:
a. State 1
The parameters given are;
T₁ = 560°C
P₁ = 12 MPa = 120 bar
Therefore;
h₁ = 3507.41 kJ/kg, s₁ = 6.6864 kJ/(kg·K)
State 2
p₂ = 1 MPa = 10 bar
s₂ = s₁ = 6.6864 kJ/(kg·K)
h₂ = (6.6864 - 6.6426)÷(6.6955 - 6.6426)×(2828.27 - 2803.52) + 2803.52
= (0.0438 ÷ 0.0529) × 24.75 = 2824.01 kJ/kg
State 3
p₃ = 6 kPa = 0.06 bar
s₃ = s₁ = 6.6864 kJ/(kg·K)
sg = 8.3291 kJ/(kg·K)
sf = 0.52087 kJ/(kg·K)
x = s₃/sfg = (6.6864- 0.52087)/(8.3291 - 0.52087) = 0.7896
(h₃ - 151.494)/2415.17 = 0.7896
∴ h₃ = 2058.56 kJ/kg
State 4
Saturated liquid state
p₄ = 0.06 bar= 6000 Pa, h₄ = 151.494 kJ/kg, s₄ = 0.52087 kJ/(kg·K)
State 5
Open feed-water heater
p₅ = p₂ = 1 MPa = 10 bar = 1000000 Pa
s₄ = s₅ = 0.52087 kJ/(kg·K)
h₅ = h₄ + work done by the pump on the saturated liquid
∴ h₅ = h₄ + v₄ × (p₅ - p₄)
h₅ = 151.494 + 0.00100645 × (1000000 - 6000)/1000 = 152.4944113 kJ/kg
Step 6
Saturated liquid state
p₆ = 1 MPa = 10 bar
h₆ = 762.683 kJ/kg
s₆ = 2.1384 kJ/(kg·K)
v₆ = 0.00112723 m³/kg
Step 7
p₇ = p₁ = 12 MPa = 120 bar
s₇ = s₆ = 2.1384 kJ/(kg·K)
h₇ = h₆ + v₆ × (p₇ - p₆)
h₇ = 762.683 + 0.00112723 * (12 - 1) * 1000 = 775.08253 kJ/kg
The fraction of flow extracted at the second stage, y, is given as follows
The turbine control volume is given as follows;
= (3507.41 - 2824.01) + (1 - 0.22840)*(2824.01 - 2058.56) = 1274.02122 kJ/kg
For the pumps, we have;
= (775.08253 - 762.683) + (1 - 0.22840)*(152.4944113 - 151.494)
= 13.17 kJ/kg
For the working fluid that flows through the steam generator, we have;
= 3507.41 - 775.08253 = 2732.32747 kJ/kg
The thermal efficiency, η, is given as follows;
η = (1274.02122 - 13.17)/2732.32747 = 0.4615 which is 46.15%
(762.683 - 152.4944113)/(2824.01 - 152.4944113)
b. The mass flow rate, , into the first turbine stage is given as follows;
= 330 *1000/(1274.02122 - 13.17) = 261.73 kg/s
c. From the entropy rate balance of the steady state form, we have;
= 261.73 * (2.1384 - 0.2284*6.6864 - (1 - 0.2284)*0.52087 = 54.79 kW/K
Answer:
Both the technicians are correct.
Explanation:
As the pressure increases the temperature will also increase in accordance with the Boyle's law hence greater amount of heat is formed.
When the temperature increases the intermolecular spaces increase as the molecules of the fuel gain energy and their kinetic energy increases. This is limited to temperatures below dissociation/combustion temperature of diesel .