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DENIUS [597]
4 years ago
12

A spacecraft is fueled using hydrazine ​(N2H4​; molecular weight of 32 grams per mole​ [g/mol]) and carries 1 comma 630 kilogram

s​ [kg] of fuel. On a mission to orbit a​ planet, the fuel will first be warmed from negative 199 degrees Fahrenheit​ [°F] to 100 degrees Fahrenheit​ [°F] before being used after the long space flight to reach the planet. The specific heat capacity of hydrazine is 0.099 kilojoules per mole kelvin​ [kJ/(mol K)]. If there is 250 watts​ [W] of power available to heat the​ fuel, how long will the heating process take in units of hours​ [h]?

Engineering
1 answer:
Varvara68 [4.7K]4 years ago
7 0

Answer:

attached below

Explanation:

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In a steam power plant, 1 MW is added in the boiler, 0.58 MW is taken out in the condenser and the pump work is 0.02 MW.
Free_Kalibri [48]

Answer:

a) \eta = 42\,\%, b) COP_{R} = 29

Explanation:

a) The thermal efficiency is:

\eta = \frac{\dot Q_{in} - \dot Q_{out}}{\dot Q_{in}}\times 100\,\%

\eta = \frac{1\,MW-0.58\,MW}{1\,MW} \,\times 100\,\%

\eta = 42\,\%

b) The coefficient of performance is:

COP_{R} = \frac{\dot Q_{L}}{\dot W}

COP_{R} = \frac{0.58\,MW}{0.02\,MW}

COP_{R} = 29

3 0
3 years ago
Explain why the following scenario fails to meet the definition of a project description.
s344n2d4d5 [400]

Answer:

The youth hockey training facility

Explanation:

7 0
4 years ago
The boost converter of Fig. 6-8 has parameter Vs 20 V, D 0.6, R 12.5 , L 10 H, C 40 F, and the switching frequency is 200 kHz. (
mr Goodwill [35]

Answer:

a) the output voltage is 50 V

b)

- the average inductor current is 10 A

- the maximum inductor current is 13 A

- the maximum inductor current is 7 A

c) the output voltage ripple is 0.006 or 0.6%V₀

d) the average current in the diode under ideal components is 4 A

Explanation:

Given the data in the question;

a) the output voltage

V₀ = V_s/( 1 - D )

given that; V_s = 20 V, D = 0.6

we substitute

V₀ = 20 / ( 1 - 0.6 )

V₀ = 20 / 0.4

V₀ = 50 V

Therefore, the output voltage is 50 V

b)

- the average inductor current

I_L = V_s / ( 1 - D )²R

given that R = 12.5 Ω, V_s = 20 V, D = 0.6

we substitute

I_L = 20 / (( 1 - 0.6 )² × 12.5)

I_L = 20 / (( 0.4)² × 12.5)

I_L = 20 / ( 0.16 × 12.5 )

I_L = 20 / 2

I_L = 10 A

Therefore, the average inductor current is 10 A

- the maximum inductor current

I_{Lmax = [V_s / ( 1 - D )²R] + [ V

given that, R = 12.5 Ω, V_s = 20 V, D = 0.6, L = 10 μH, T = 1/200 kHz = 5 hz

we substitute

I_{Lmax = [20 / (( 1 - 0.6 )² × 12.5)] + [ (20 × 0.6 × 5) / (2 × 10) ]

I_{Lmax = [20 / 2 ] + [ 60 / 20 ]    

I_{Lmax = 10 + 3

I_{Lmax = 13 A

Therefore, the maximum inductor current is 13 A

- The minimum inductor current

I_{Lmax = [V_s / ( 1 - D )²R] - [ V

given that, R = 12.5 Ω, V_s = 20 V, D = 0.6, L = 10 μH, T = 1/200 kHz = 5 hz

we substitute

I_{Lmin = [20 / (( 1 - 0.6 )² × 12.5)] - [ (20 × 0.6 × 5) / (2 × 10) ]

I_{Lmin = [20 / 2 ] -[ 60 / 20 ]    

I_{Lmin = 10 - 3

I_{Lmin  = 7 A

Therefore, the maximum inductor current is 7 A

 

c)  the output voltage ripple

ΔV₀/V₀ = D/RCf

given that; R = 12.5 Ω, C = 40 μF = 40 × 10⁻⁶ F, D = 0.6, f = 200 Khz = 2 × 10⁵ Hz

we substitute

ΔV₀/V₀ = 0.6 / (12.5 × (40 × 10⁻⁶) × (2 × 10⁵) )

ΔV₀/V₀ = 0.6 / 100

ΔV₀/V₀ = 0.006 or 0.6%V₀

Therefore, the output voltage ripple is 0.006 or 0.6%V₀

d) the average current in the diode under ideal components;

under ideal components; diode current = output current

hence the diode current will be;

I_D = V₀/R

as V₀ = 50 V and R = 12.5 Ω

we substitute

I_D = 50 / 12.5

I_D = 4 A

Therefore, the average current in the diode under ideal components is 4 A

7 0
3 years ago
Consider a nuclear power plant that produces 1200 MW of power and has a conversion efficiency of 34 percent (that is, for each u
KIM [24]

Answer with Explanation:

The relation between power and energy is

Energy=Power\times Time

Since the nuclear reactor operates at 1200 MW throughout the year thus the energy produced in 1 year equals

E=1200\times 10^{6}\times 3600\times 24\times 365=3.784\times 10^{16}

Now from the energy mass equivalence we have

E=mass\times c^2

where

'c' is the speed of light in free space

Thus equating both the above values we get

3.784\times 10^{16}=mass\times (3\times 10^{8})^{2}\\\\\therefore mass=\frac{3.784\times 10^{16}}{9\times 10^{16}}=0.42kg

Since it is given that 1 kg of mass is 34% effective thus the mass reuired for the reactor is

mass_{req}=\frac{mass}{\eta }=\frac{0.43}{0.34}=1.235

Thus 1.235 kg of nuclear fuel is reuired for operation.

7 0
4 years ago
A long, circular aluminum rod is attached at one end to a heated wall and transfers heat by convection to a cold fluid.
Trava [24]

Answer:

a. Heat removal rate will increase

b. Heat removal rate will decrease

Explanation:

Given that

One end of rod is connected to the furnace and rod is long.So this rod can be treated as infinite long fin.

We know that heat transfer in fin given as follows

Q_{fin}=\sqrt{hPKA}\ \Delta T

We know that area

A=\dfrac{\pi}{4}d^2

Now when diameter will triples then :

A_f=\dfrac{\pi}{4}{\left (3d \right )}^2

A_f=9A

Q'_{fin}=\sqrt{9hPKA}\ \Delta T

Q'_{fin}=3\sqrt{hPKA}\ \Delta T

Q'_{fin}=3Q

So the new heat transfer will increase by 3 times.

Now when copper rod will replace by aluminium rod :

As we know that thermal conductivity(K) of Aluminium is low as compare to Copper .It means that heat transfer will decreases.

3 0
3 years ago
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