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.

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