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dolphi86 [110]
3 years ago
7

Air is compressed in an isentropic process from an initial pressure and temperature of P1 = 90 kPa and T1=22°C to a final pressu

re of P2=900 kPa. Determine: a)- The final temperature of the air. b)-The work done per kg of air during the process.
Engineering
1 answer:
ivolga24 [154]3 years ago
4 0

Answer:

a) T_2=569.35 K

b)Work done per kg of air=196.84 KJ/Kg

Explanation:

Given: \gamma =1.4 for air.

P_1=90 KPa ,T_=22^\circ C,P_2=900 KPa

We know that  

\dfrac{T_2}{T_1}=\left (\frac{P_2}{P_1}\right )^{\dfrac{{\gamma-1}}{\gamma}}

So  \dfrac{T_2}{295}=\left (\frac{900}{90}\right )^{\dfrac{{1.4-1}}{1.4}}

T_2=569.35 K

(a) T_2=569.35 K

(b)Work for adiabatic process

  W=\frac{P_1V_1-P_2V_2}{\gamma -1}

We know that PV=mRT for ideal gas.

 W=mR\frac{T_1-T_2}{\gamma -1}

Now by putting values

work per kg of air=0.287\times \frac{295-569.35}{1.4 -1}

Work w=-196.84 KJ/Kg    (Negative sign indicate work given to input.)

So work done per kg of air=196.84 KJ/Kg

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Water at 15°C is to be discharged from a reservoir at a rate of 18 L/s using two horizontal cast iron pipes connected in series
love history [14]

Answer:

The required pumping head is 1344.55 m and the pumping power is 236.96 kW

Explanation:

The energy equation is equal to:

\frac{P_{1} }{\gamma } +\frac{V_{1}^{2}  }{2g} +z_{1} =\frac{P_{2} }{\gamma } +\frac{V_{2}^{2}  }{2g} +z_{2}+h_{i} -h_{pump} , if V_{1} =0,z_{2} =0\\h_{pump} =\frac{V_{2}^{2}}{2} +h_{i}-z_{1}

For the pipe 1, the flow velocity is:

V_{1} =\frac{Q}{\frac{\pi D^{2} }{4} }

Q = 18 L/s = 0.018 m³/s

D = 6 cm = 0.06 m

V_{1} =\frac{0.018}{\frac{\pi *0.06^{2} }{4} } =6.366m/s

The Reynold´s number is:

Re=\frac{\rho *V*D}{u} =\frac{999.1*6.366*0.06}{1.138x10^{-3} } =335339.4

\frac{\epsilon }{D} =\frac{0.00026}{0.06} =0.0043

Using the graph of Moody, I will select the f value at 0.0043 and 335339.4, as 0.02941

The head of pipe 1 is:

h_{1} =\frac{V_{1}^{2}  }{2g} (k_{L}+\frac{fL}{D}  )=\frac{6.366^{2} }{2*9.8} *(0.5+\frac{0.0294*20}{0.06} )=21.3m

For the pipe 2, the flow velocity is:

V_{2} =\frac{0.018}{\frac{\pi *0.03^{2} }{4} } =25.46m/s

The Reynold´s number is:

Re=\frac{\rho *V*D}{u} =\frac{999.1*25.46*0.03}{1.138x10^{-3} } =670573.4

\frac{\epsilon }{D} =\frac{0.00026}{0.03} =0.0087

The head of pipe 1 is:

h_{2} =\frac{V_{2}^{2}  }{2g} (k_{L}+\frac{fL}{D}  )=\frac{25.46^{2} }{2*9.8} *(0.5+\frac{0.033*36}{0.03} )=1326.18m

The total head is:

hi = 1326.18 + 21.3 = 1347.48 m

The required pump head is:

h_{pump} =\frac{25.46^{2} }{2*9.8} +1347.48-36=1344.55m

The required pumping power is:

P=Q\rho *g*h_{pump}  =0.018*999.1*9.8*1344.55=236965.16W=236.96kW

8 0
3 years ago
How can you evaluate whether the slope of the dependent variable with an independent variable is the same for each level of the
s2008m [1.1K]

Answer:

By running multiple regression with dummy variables

Explanation:

A dummy variable is a variable that takes on the value 1 or 0. Dummy variables are also called binary

variables. Multiple regression expresses a dependent, or response, variable as a linear

function of two or more independent variables. The slope is the change in the response variable. Therefore, we have to run a multiple regression analysis when the variables are measured in the same measurement.The number of dummy variables you will need to capture a categorical variable

will be one less than the number of categories. When there is no obvious order to the categories or when there are three or more categories and differences between them are not all assumed to be equal, such variables need to be coded as dummy variables for inclusion into a regression model.

3 0
3 years ago
A horizontal curve on a two-lane road is designed with a 2,300-ft radius, 12-ft lanes, and a 65-mph design speed. Determine the
Ierofanga [76]

Answer:

distance = 22.57 ft

superelevation rate = 2%

Explanation:

given data

radius = 2,300-ft

lanes width = 12-ft

no of lane = 2

design speed = 65-mph

solution

we get here sufficient sight distance SSD that is express as

SSD = 1.47 ut + \frac{u^2}{30(\frac{a}{g}\pm G)}     ..............1

here u is speed and t is reaction time i.e 2.5 second and a is here deceleration rate i.e 11.2 ft/s² and g is gravitational force i.e 32.2 ft/s² and G is gradient i.e 0 here

so put here value and we get

SSD = 1.47 × 65 ×2.5  + \frac{65^2}{30(\frac{11.2}{32.2}\pm 0)}

solve it we get

SSD = 644 ft  

so here minimum distance clear from the inside edge of the inside lane is

Ms = Rv ( 1  - cos (\frac{28.65 SSD}{Rv}) )        .....................2

here Rv is = R - one lane width

Rv = 2300 - 6 = 2294 ft

put value in equation 2 we get

Ms = 2294 ( 1  - cos (\frac{28.65 \times 664}{2294})  )  

solve it we get

Ms = 22.57 ft

and

superelevation rate for the curve will be here as

R  = \frac{u^2}{15(e+f)}  ..................3

here f is coefficient of friction that is 0.10

put here value and we get e

2300 = \frac{65^2}{15(e+0.10)}

solve it we get

e = 2%

3 0
2 years ago
Every two years or at recommendation by manufacturer.
9966 [12]

Answer:

Manufacturer’s Recommendations means the instructions, procedures, and recommendations which are issued by the manufacturer of any equipment used at the Facility relating to the operation, maintenance, or repair of such equipment, and any revisions or updates thereto from time to time issued by the manufacturer.

Manufacturer’s Recommendations means the instructions, procedures and recommendations which are issued by any manufacturer of the Equipment relating to the operation, maintenance and repair of the Equipment and any revisions to such instructions, procedures and recommendations agreed to by any manufacturer of the Equipment and which are valid at the time such operation, repair and maintenance is being carried out.

Manufacturer’s Recommendations means the written instructions, procedures and recommendations which are issued by the original equipment manufacturer of any plant or equipment used at the Utility Plant relating to the operation, maintenance and repair of such plant or equipment and any revisions thereto issued by the manufacturer, which are valid and applicable at the time such operation, maintenance or repair is undertaken. Notwithstanding the above, Manufacturer’s Recommendations shall not include any instructions, procedures or recommendations of a manufacturer of any plant or equipment that the Owner and the Operator have agreed in writing to exclude from this definition or have agreed in writing should not be followed.

Explanation:

4 0
2 years ago
you have a permanent magnet whit remanent induction. than you cut a piec of that magnet. if you put that piece back into permane
ELEN [110]
Yes, it will. The induction will be the same as long as it’s put back together.
5 0
3 years ago
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