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# Need Help asap

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An engine operating on the diesel cycle with air as the working fluid has a maximum pressure of P = 1.50 MPa and maximum temperature T = 1200 K; the volume at this state is 1.3 L. The compression ratio is 8 and the heat addition is 1.0 kJ. The compression process is polytropic with n = 1.35, while all other processes are ideal.

a.   Sketch the P-v diagram

Calculate:

b.   The cutoff ratio [Hint: if you are using Table A-2(b) or A-17 to solve this problem, you will have to use an iterative (trial-and-error) approach to find both states. Using any of Table A-2(a), A-2(b) or A-17 is acceptable.]

c.   The heat transfer out

d.   The thermal efficiency

e.   The mean effective pressure

Report:

f.   A table showing the temperature and pressure of each state

g.   A table showing the work done and heat transfer for each process

Note that you cannot simply apply the formula:

for the thermal efficiency in this case because the compression and expansion processes are not both isentropic.

Guest Jun 4, 2014

#7
+2353
+5

AAARGH!

I KNEW IT!

I always thought you were a pirate!

reinout-g  Jun 6, 2014
Sort:

#2
+2353
+5

What applies to this guy,

is pretty much what applies to you.

If you genuinly have no idea how to begin, then ask us a more specific question.

For example, you might not have a clue what a PV diagram is.

I just filled it in in google and the first thing I found was a pressure volume diagram...

Okay, so what's next?

I want to know how pressure relates to volume right?

First hit; wikipedia- Boyle's law

What do I see?

I see Pressure*Volume = k

where k is a constant.

Hey! if k is a constant, than I can make a graph!.

But how do I calculate k?

Now you have a specific question;

You know this ; 'An engine operating on the diesel cycle with air as the working fluid has a maximum pressure of P = 1.50 MPa and maximum temperature T = 1200 K; the volume at this state is 1.3 L. The compression ratio is 8 and the heat addition is 1.0 kJ. The compression process is polytropic with n = 1.35, while all other processes are ideal.' and want to know how pressure and volume are related.

Sorry for beeing so harsh on you, but every now and then we simply are.

reinout

reinout-g  Jun 6, 2014
#3
+85809
0

Actually, reinout......he lost me at the word "polytropic"...........

CPhill  Jun 6, 2014
#4
+2353
0

Aww c'mon Chris,

you obviously now what polytropic is,

You know, the opposite of monotropic where it is only tropic and not multiple tropic

reinout-g  Jun 6, 2014
#5
+2353
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reinout-g  Jun 6, 2014
#6
+85809
+3

LOL!!!!

Actually...the only "poly" I'm familiar with is when my bird says, " 'Poly' want a cracker."

CPhill  Jun 6, 2014
#7
+2353
+5

AAARGH!

I KNEW IT!

I always thought you were a pirate!

reinout-g  Jun 6, 2014

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