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MrRa [10]
3 years ago
14

Steam enters an adiabatic turbine at 6 MPa, 600°C, and 80 m/s and leaves at 50 kPa, 100°C, and 140 m/s. If the power output of t

he turbine is 5 MW, determine (a) the reversible power output and (b) the second-law efficiency of the turbine. Assume the surroundings to be at 25°C.
Engineering
1 answer:
attashe74 [19]3 years ago
6 0

Answer:

(a) the reversible power output of turbine is 5810 kw

(b) The second-law efficiency of he turbine = 86.05%

Explanation:

In state 1: the steam has a pressure of 6 MPa and 600°C. Obtain the enthalpy and entropy at this state.

h1 = 3658 kJ/kg s1=7.167 kJ/kgK

In state 2: the steam has a pressure of 50 kPa and 100°C. Obtain the enthalpy and entropy at this state

h2 = 2682kl/kg S2= 7.694 kJ/kg

Assuming that the energy balance equation given  

Wout=m [h1-h2+(v1²-v2²) /2]

Let

W =5 MW

V1= 80 m/s  V2= 140 m/s

h1 = 3658kJ/kg  h2 = 2682 kJ/kg

∴5 MW x1000 kW/ 1 MW =m [(3658-2682)+ ((80m/s)²-(140m/s)²)/2](1N /1kg m/ s²) *(1KJ/1000 Nm)

m = 5.158kg/s

Consider the energy balance equation given  

Wrev,out =Wout-mT0(s1-s2)

Substitute Wout =5 MW m = 5.158kg/s 7

s1=  7.167 kJ/kg-K            s2= 7.694kJ/kg-K and 25°C .

Wrev,out=(5 MW x 1000 kW /1 MW) -5.158x(273+25) Kx(7.167-7.694)

= 5810 kW

(a) Therefore, the reversible power output of turbine is 5810 kw.

The given values of quantities were substituted and the reversible power output are calculated.

(b) Calculating the second law efficiency of the turbine:  

η=Wout/W rev,out

Let Wout =  5 MW and Wrev,out = 5810 kW  

η=(5 MW x 1000 kW)/(1 MW *5810)  

η= 86.05%

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gulaghasi [49]

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In an international film festival, a penal of 11 judges is formed to judge the best film. At
Julli [10]

Answer:

International Film Festival

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= 33%.

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2. Classical probability can only handle events where each outcome is equally likely.

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Explanation:

a) Number of judges = 11

Number of judges in favor of FA film = 6

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In a production facility, 3 cm thick large brass plates (k = 110 W/mC, α = 33.9 × 10-6 m2 /s) that are initially at a uniform
zysi [14]

Answer:

Explanation:

Given.

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Thermal conductivity of brass k = 110 W/m.°C

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Specific heat of brass C_p =380J/kg.°C

Thermal diffusivity of brass \alpha = 33.9\times 10^{-6} m^2/s

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The initial temperature T_i= 25°C

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The thermal properties of the plate are constant.

The heat transfer coefficient is constant and uniform over the entire surface.

The Fourier number is > 0.2 so that the one-term approximate solutions (or the transient  temperature charts) are applicable (this assumption will be verified).

The Biot number for this process Bi = \frac{hL}{k}\\\\Bi=\frac{(80 W/m^2.°C)(0.015 m)}{(110 W/m.°C)}\\=Bi =0.0109

The constants \lambda_1 and A_1 corresponding to this Biot are, from 11-2 tables.

The interpolation method used to find the

\lambda_1=0.1039  and A_1=1.0018
  

The Fourier number \tau=\frac{\alpha t}{L^2}\\\\\tau=\frac{(33.9\times 10^{-6} m^2/s)(10 min \times 60 s/min)}{(0.015m)^2}
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2 years ago
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lapo4ka [179]

Answer:

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l =\frac{0.30 }{0.04 } \times \lambda

  = 7.5 \lambda

Because it is an integrated half-wavelength amount,

Z_{in} = Z_L = 150 \ \Omega

8 0
3 years ago
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