Isobaric Process - Entropy in Terms of Pressure and Volume

on . Posted in Thermodynamics

Isobaric process is a thermodynamic process where the pressure is kept constant, \(\Delta p = 0\).

 

Isobaric process - entropy in terms of pressure and volume Formula

\( S  =  \Delta S \; ( - n\; R ) \; [ \; ln \; ( p_f \;/\; p_i )  \; ]  \) 
Symbol English Metric
\( S \) = entropy \(Btu \;/\; lbm-R\) \(kJ \;/\;kg-K\)
\( \Delta S \) = change in entropy \(Btu \;/\; lbm-R\) \(kJ \;/\;kg-K\)
\( n \) = number of moles \(dimensionless\)
\( R \) = molar gas constant \(lbf-ft \;/\; lbmol-R\) \(J \;/\; kmol-K\)
\( ln \) = natural logarithm \(dimensionless\)
\( p_f \) = final pressure \(lbf \;/\; in^2\) \(Pa\)
\( p_i \) = initial pressure \(lbf \;/\; in^2\) \(Pa\)

   

Isobaric process - entropy in terms of pressure and volume Formula

\( S  =  \Delta S \; ( n\; R ) \; [ \; ln \; ( V_f \;/\; V_i ) \; ] \) 
Symbol English Metric
\( S \) = entropy \(Btu \;/\; lbm-R\) \(kJ \;/\;kg-K\)
\( \Delta S \) = change in entropy \(Btu \;/\; lbm-R\) \(kJ \;/\;kg-K\)
\( n \) = number of moles \(dimensionless\)
\( R \) = molar gas constant \(lbf-ft \;/\; lbmol-R\) \(J \;/\; kmol-K\)
\( ln \) = natural logarithm \(dimensionless\)
\( V_f \) = final volume \(in^3\) \(mm^3\)
\(V_i \) = initial volume \(in^3\) \(mm^3\)

 

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Tags: Pressure Heat Volume Energy Constant Entropy