You should use the pass technique a fire extinguisher
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Answer:
a)31%
b)34MW
Explanation:
A rankine cycle is a generation cycle using water as a working fluid, when heat enters the boiler the water undergoes a series of changes in state and energy until generating power through the turbine.
This cycle is composed of four main components, the boiler, the pump, the turbine and the condenser as shown in the attached image
To solve any problem regarding the rankine cycle, enthalpies in all states must be calculated using the thermodynamic tables and taking into account the following.
• The pressure of state 1 and 4 are equal
• The pressure of state 2 and 3 are equal
• State 1 is superheated steam
• State 2 is in saturation state
• State 3 is saturated liquid at the lowest pressure
• State 4 is equal to state 3 because the work of the pump is negligible.
Once all enthalpies are found, the following equations are used using the first law of thermodynamics
Wout = m (h1-h2)
Qin = m (h1-h4)
Win = m (h4-h3)
Qout = m (h2-h1)
The efficiency is calculated as the power obtained on the heat that enters
Efficiency = Wout / Qin
Efficiency = (h1-h2) / (h1-h4)
For this problem, we will first find the enthalpies in all states
h1=3231kJ/Kg
h2=2310kJ/Kg
h3=h4=272kJ/Kg
A) using the eficiency ecuation
Efficiency = (h1-h2) / (h1-h4)
Efficiency =(3231-2310)/(3231-272)=0.31=<u>31%</u>
b)using ecuation for Wout
Wout = m (h1-h2)
Wout=37(3231-2310)=34077KW=<u>34.077MW</u>
Based on the Chvorinov's rule, the diference in the <em>solidification</em> times of the two castings is 14.092 times the <em>solidification</em> time of the prism casting.
<h3>How to apply the Chvorinov's rule for casting processes</h3>
The Chvorinov's rule is an empirical method to estimate the cooling time of a casting in terms of a <em>reference</em> time. This rule states that cooling time (<em>t</em>) is directly proportional to the square of the volume (<em>V</em>), in cubic meters, divided to the surface area (<em>A</em>), in square meters. Now we proceed to model each casting:
<h3>Cylindrical casting</h3>t = C · [0.25π · D² · L/(0.5π · D² + π · D · L)]²
t = C · [0.25 · D · L/(0.5 · D + L)]² (1)
<h3>Prism casting</h3>t' = C · [3 · T² · L/(6 · T · L + 2 · T · L + 6 · T²)]²
t' = C · [3 · T · L/(8 · L + 6 · T)]² (2)
<h3>Relationship between the cross sections of both castings</h3>3 · T² = 0.25π · D² (3)
Where:
- <em>t</em> - Cooling time of the cylindrical casting, in time unit.
- <em>t'</em> - Cooling time of the prism casting, in time unit.
- <em>C</em> - Cooling factor, in time unit per square meter.
- <em>D</em> - Diameter of the cylinder, in meters.
- <em>L</em> - Length of the casting, in meters.
- <em>T</em> - Width of the cross section of the prism casting, in meters.
If we know that <em>D =</em> <em>0.3 m</em>, then the thickness of the prism casting is:
<em>T ≈ 0.153 m</em>
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And (1) and (2) simplified into these forms:
<h3>Cylindrical casting</h3>t = C · {0.25π · (0.3 m) · (0.5 m)/[0.5 · (0.3 m) + 0.5 m]}²
t = 0.0329 · C (1b)
<h3>Prism casting</h3>t' = C · {3 · (0.153 m) · (0.5 m)/[8 · (0.5 m) + 6 · (0.153 m)]}²
t' = 0.00218 · C (2b)
Lastly we find the <em>percentual</em> difference in the solidification times of the two castings by using the following expression:
<em>r = (</em>1 <em>- t'/t) ×</em> 100 %
<em>r = (</em>1 <em>-</em> 0.00218<em>/</em>0.0329<em>) ×</em> 100 %
<em>r =</em> 93.374 %
The <em>cooling</em> time of the <em>prism</em> casting is 6.626 % of the <em>solidification</em> time of the <em>cylindrical</em> casting. The diference in the <em>solidification</em> times of the two castings is 14.092 times the <em>solidification</em> time of the <em>prism</em> casting.
To learn more on solidification times, we kindly invite to check this verified question: brainly.com/question/13536247