Isentropic process formula. The isentropic process a special case of adiabatic process can be expressed with the ideal gas law as. Consequently in order to maintain constant entropy within the system energy must be removed from the system as heat during the process. For a closed system the total change in energy of a system is the sum of the work done and the heat added d u d w d q. Pv k constant.
An isentropic process is an idealization of an actual process and serves as a limiting case for an actual process. In an irreversible process of transfer of energy as work entropy is produced within the system. For an isentropic process which by definition is reversible there is no transfer of energy as heat because the process is adiabatic dq 0. For an ideal gas undergoing isentropic process or.
P 1 v 1 k p 2 v 2 k. The work required for the compressor is given by wc h2 h1. Derivation of the isentropic relations. S2 s1 cp ln t2 t1 r ln p2 p1 where the numbers 1 and 2 denote the states at the beginning and end of the compression process s is the entropy t is the temperature p is the pressure and ln denotes the natural logarithm function.
One for constant pressure c p and one for constant volume c v. P 1 v 1 k p 2 v 2 k. Isentropic compression ambient air is drawn into the compressor where it is pressurized 1 2. It is a special case of the adiabatic processes defined as a reversible adiabatic process.
Isobaric heat addition the compressed air then runs through a combustion chamber where fuel is burned and air or another medium is heated 2 3. Displaystyle dudelta wdelta q. Now we use the equation we have derived for the entropy of a gas. In which k c p c v is the ratio of the specific heats or heat capacities for the gas.
Pv k constant. The relations of entropy change for ideal gases are 1 and 2 by setting d s to 0 in the above equations the relations for an ideal. Thermodynamic work done on a system undergoing isentropic process is given by. The outlet temperature of the gas t 4is can be calculated using p v t relation for isentropic process reversible adiabatic process.
Notice the important role that the mach number plays in all the equations on the right side of this slide. Isentropic process is characterized by constant entropy of the system. One for constant pressure c p and one for constant volume c v. A a 1 m2 gam 12 gam1 gam 12 gam12 gam1 gam 12 m.
Isentropic processes for ideal gases an isentropic process of ideal gases on a t s diagram. In which k c p c v is the ratio of the specific heats or heat capacities for the gas.