Thermodynamics and Compression Ignition Pressure and Temp Problem?

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SUMMARY

The discussion focuses on solving a thermodynamics problem related to a model diesel compression ignition (C.I) engine with a volumetric compression ratio of 18:1 and a cutoff ratio of 1.5:1. The initial conditions are given as p1 = 1 bar and T1 = 27°C. The solution involves using the equations p1V1/T1 = p2V2/T2 and p1V1^n = p2V2^n, leading to the calculation of T2 as 954K. The process includes isentropic compression, isobaric expansion, adiabatic expansion, and isochoric decompression, utilizing the ideal gas law to derive pressures and volumes at each stage of the cycle.

PREREQUISITES
  • Understanding of the Diesel cycle and its stages
  • Familiarity with the ideal gas law (PV = nRT)
  • Knowledge of isentropic processes in thermodynamics
  • Proficiency in using thermodynamic equations for pressure and temperature calculations
NEXT STEPS
  • Study the derivation and application of the ideal gas law in thermodynamic cycles
  • Learn about the specifics of the Diesel cycle and its efficiency calculations
  • Explore isentropic processes and their implications in engine performance
  • Investigate the effects of varying compression and cutoff ratios on engine output
USEFUL FOR

Students studying mechanical engineering, particularly those focusing on thermodynamics and engine design, as well as professionals involved in engine performance optimization and analysis.

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Homework Statement



A model diesel C.I engine has a volumetric compression ratio of 18:1 and a cut*off ratio of 1.5:1?
The engine has a volumetric compression ratio of 18:1 and a cut*off ratio of
1.5:1.

If p1 = 1 bar and T1 = 27°C, determine the pressure and temperature
at each point in the cycle.

How would I do this?

Homework Equations



p1V1/T1=p2V2/T2

p1V1^n=p2V2^n

The Attempt at a Solution



T2 = 18^(1.4-1)*300 = 954K

No idea how to work out the pressures. I know it is isentropic so p1V1^n=p2V2^n
 
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The Diesel cycle consists of the following:
1. adiabatic (isentropic) compression from p1 v1 to p2 v2
2. isobaric expansion from p2 v2 to p2 v3
3. adiabatic expansion from p2 v3 to p4 v1
4. isochoric (constant-volume) decompression from p4 v1 to p1 v1.

Just use the ideal gas relation pv = RT to get all the above p's and v's.
Realize that compression ratio = v1/v2 and cutoff ratio = v3/v2.
 

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