I calculating the maximum pressure

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    Maximum Pressure
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SUMMARY

The discussion focuses on calculating the maximum pressure in a thermodynamic cycle involving isothermal compression, isobaric expansion, and isochoric cooling. The user provided specific values including R = 0.287 kJ/kg K and Cp = 1.005 kJ/kg K, and used the ideal gas law (PV = nRT) to determine the mass of air present as 247.90 g. The user also attempted to calculate the maximum pressure using the formula vm = (Qp / (4 x Z)), resulting in a value of 1925.958. The calculations require verification for accuracy.

PREREQUISITES
  • Understanding of thermodynamic cycles, specifically isothermal, isobaric, and isochoric processes.
  • Familiarity with the ideal gas law (PV = nRT) and its application in thermodynamics.
  • Knowledge of specific heat capacities, particularly Cp and Cv, in relation to gas laws.
  • Basic proficiency in unit conversions, especially between kJ, atm, and liters.
NEXT STEPS
  • Review the derivation and application of the ideal gas law in thermodynamic calculations.
  • Study the principles of isothermal and isobaric processes in greater detail.
  • Learn about the significance of specific heat capacities (Cp and Cv) in thermodynamic cycles.
  • Explore advanced thermodynamic equations and their applications in calculating pressure and volume changes.
USEFUL FOR

This discussion is beneficial for students and professionals in mechanical engineering, particularly those focusing on thermodynamics, as well as anyone involved in HVAC systems or gas compression technologies.

xto
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I've serach for almost a day now ,
just to search the formula to calculate the maximum pressure in the cycle
A very big thank you and appreciate for the help
 
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What cycle specifically are you referring to, xto? Could you please provide a more complete problem description, and show us what you have tried so far?
 
i)isothermal compresssion from state 1 through a volumetric compression ration of 6 to state 2
ii) isobaric expansion from state 2 back to the initial volume thus reaching state 3
iii) isochoric cooling from state 3 back to the original pressure to reach state

it ask for the mass of air present and the maximum pressure in the cycle

Given
R=0.287 kj/kg K
Cp=1.005 Kj/KG K

i have done
pv=nrt
t=303K
p=1.2x0.9869
=1.1832
V=2.2x1000
=2.2x10^3

so (1.1832atm)(2.2x10^3L)
-----------------------
(1.005) (303K)

which the ans is 247.90g Air

then i use this formula
vm=(Qp/4 x Z)
so (2.2x10^3)(1.005)/4x(0.287)
which get
1925.958

i'm not sure if it's rite or not
please help , thx
 
Last edited:

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