Answer:
<em>a) 50 J/kg</em>
<em>b) 721 67 KW</em>
<em></em>
Explanation:
The velocity of the wind v = 10 m/s
diameter of the blades d = 70 m
efficiency of the turbine η = 30%
density of air ρ = 1.25 kg/m^3
The area of the blade A = 
A = 
= 3848.95 m^2
The mechanical energy air per unit mass is gives as
e = 
= 
= <em>50 J/kg</em>
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Theoretical Power of the turbine P = ρAve
where
ρ is the density of air
A is the area of the blade
v is the velocity of the wind
e is the energy per unit mass
substituting values, we have
P = 1.25 x 3848.95 x 10 x 50 = 2405593.75 W
Actual power = ηP
where η is the efficiency of the turbine
P is the theoretical power of the turbine
Actual power = 0.3 x 2405593.75 = 721678.1 W
==> <em>721 67 KW</em>
Answer:
In engineering design, failure is expected. It helps you find the best solutions before implementing them in the “real world”. Having a prototype fail is a GOOD thing, because that means you have learned something new about the problem and potential solutions.
Explanation:
Answer with Explanation:
1) The advantages of fission energy are:
a) Higher concentration of energy : Concentration of energy or the energy density is defined as the amount of energy that is produced by burning a unit mass of the fuel. The nuclear energy obtained by fission has the highest energy density among all the other natural sources of energy such as coal,gas,e.t.c.
b) Cheap source of energy : The cost at which the energy is produced by a nuclear reactor after it is operational is the lowest among all the other sources of energy such as coal, solar,e.t.c
2) The disadvantages of fission energy are:
a) Highly dangerous residue: The fuel that is left unspent is highly radioactive and thus is very dangerous. Usually the residual material is taken deep into the earth for it's disposal.
b) It has high initial costs of design and development: The cost to design a nuclear reactor and to built one after it is designed is the most among all other types of energy sources and requires highly skilled personnel for operation.
Answer:
-6.326 KJ/K
Explanation:
A) the entropy change is defined as:
In an isobaric process heat (Q) is defined as:
Replacing in the equation for entropy
m is the mass and Cp is the specific heat of R134a. We can considerer these values as constants so the expression for entropy would be:
Solving the integral we get the expression to estimate the entropy change in the system
The mass is 5.25 Kg and Cp for R134a vapor can be consulted in tables, this value is 
We can get the temperature at the beginning knowing that is saturated vapor at 500 KPa. Consulting the thermodynamic tables, we get that temperature of saturation at this pressure is: 288.86 K
The temperature in the final state we can get it from the heat expression, since we know how much heat was lost in the process (-976.71 kJ). By convention when heat is released by the system a negative sign is used to express it.
With 
clearing for T2 we get:
Now we can estimate the entropy change in the system
The entropy change in the system is negative because we are going from a state with a lot of disorder (high temperature) to one more organize (less temperature. This was done increasing the entropy of the surroundings.
b) see picture.
