Mechanical Engineering - Compressors, Gas Dynamics and Gas Turbines - Discussion

1. 

In a four stage compressor, if the pressure at the first and third stage are 1 bar and 16 bar, then the delivery pressure at the fourth stage will be

[A]. 1 bar
[B]. 16 bar
[C]. 64 bar
[D]. 256 bar

Answer: Option C

Explanation:

No answer description available for this question.

Hardik Patel said: (Jul 15, 2013)  
In multistage compressor the pressure in each stage follows geometric progression:

For 2nd stage: SQRT (1*16) = 4.

For fourth stage: 4*4*4 = 64.

Nanu Dayma said: (Nov 5, 2013)  
Four stage compressor 3rd stage me intercooler hota so its temperature and pressure is constant 4 stage compressed so increased delivery pressure.

Abhishek Chavan said: (Nov 20, 2013)  
How to came 64 please explain the example?

Guna said: (Feb 15, 2014)  
How to came 64?

Karthik said: (Mar 29, 2014)  
How does it came 64?

Kanhai said: (Apr 24, 2014)  
We know in multistage compressor:
P2/P1 = P3/P2 = P4/P3.

Since,
P3 = 16.
P1 = 1.

So from,
P2/P1 = P3/p2.

Hence,
P2 = 4.

Now P3/P2 = P4/P3.
P4 = 64.

Francies said: (Aug 7, 2014)  
We know that p2 = (p1p3)^(1/2).

Therefore p2 = (1*16)^(1/2),
p2 = 4 bar.

Therefore P4/p2=p3/p1,
P4 = 64 bar.

Deepak Kumar said: (Nov 11, 2014)  
When we know that for multistage compressor p2/p1 = p3/p2 = p4/p3.

Since p3 = 16, p1 = 1 so p2/p1 = p3/p2 then p2 = 4 also p3/p2 = p4/p3.

16/4 = p4/16.

p4 = 64.

Rajeev Raj Singh said: (Dec 2, 2015)  
Since pressure ratio is constant for a compressor. So firstly found pressure ratio. And then make dual like p2/p1=p3/p2=p4/p3 and solve this.

Bipin said: (Jun 20, 2016)  
The answer can get by following this one P2/P1 = P3/P2 = P4/P3.

Anj said: (Apr 25, 2017)  
Fourth stage means P5/P4 = 4*4*4*4 = 256.

Narasimha said: (Jul 22, 2017)  
For multi satge compressor p2/p1=p3/p2=p4/p3,
p2/p1=p3/p2 from here we get p2=4 then by this relation p4/p3=p3/p2,
p4=64.

Parseltounge said: (Aug 3, 2017)  
It follows a geometric pattern.

Mohit Kumar said: (Oct 23, 2017)  
Good explanation @Natasha.

Amit Ankush Vidarbh said: (Mar 22, 2018)  
The delivery of forth stage=p5.

p5=256.

Pradeep said: (Nov 6, 2018)  
And P5=256.

Rahul said: (Jun 10, 2019)  
Thanks all for explaining.

Mayur Desai said: (Jul 7, 2019)  
There is clearly mentioned about four stage it means;

(P2/P1)*(P3*P2)*(P4*P3)*(P5*P4)= 4*4*4*4=256.
So, the right answer is D.

Rohit said: (Sep 23, 2019)  
The delivery of forth stage = p5.

p5 = 256.

Suresh said: (Nov 16, 2019)  
The first two values given are delivery pressures at 1st and 3rd stage compressors, we have to find delivery pressure at 4th compressor.

We have p3/p2 = p4/p3 = p5/p4.
p2 = 1, p4 = 16, p5 = ?

=> p3 = (1*16)^(1%2),=> p3 = 4.
Similarly p4 = (p3*p5)^(1%2) => p5 = 64.

Savan Kumar said: (Jan 4, 2020)  
Thank you @Suresh.

Vinod said: (Jan 11, 2020)  
Why 256 bar is wrong? Explain.

Sekhar said: (Feb 20, 2020)  
The answer must be" D".

Because delivery pressure at the fourth stage means we should find P5, not P4. So P5 = 4^4.

Tarik said: (Apr 4, 2020)  
D is the answer.

Bawa said: (Apr 10, 2020)  
Thanks @Suresh.

Jyoti Dutta said: (Jun 26, 2020)  
In third stage, why intercooler isb fitted. And how the pressure is increasing? Can anyone briefly destribe about this topic?

Munish said: (Jun 29, 2020)  
P2/p1 = p3/p2 = p4/p3 By using this we will get the answer.

Hithuman45 said: (Nov 3, 2020)  
Good explanation, thanks @Suresh.

Brajesh Lakhera said: (Mar 18, 2021)  
The delivery pressure at the fourth stage means p5.

So p1 is 1.
P2 is 4.
P3 is 16.
P4 is 64.
P5 is 256.

So option D. 256 should be correct.

Aneesh Paum said: (Apr 20, 2021)  
@All.

The pressure mentioned in the question are the Delivery pressure. If we assume P2 as 1 bar and P4 as 16 bar, then only P5 comes as 64 bar.

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