Original equation for entropy change:
First of all we will consider ds = du / t + pu /t
= cu dt / t + R du / u from equation of 9.3 and then coming to Entropy change between state 1 – 2 :
= 2ʃ1 ds = 2ʃ1 cvdT/ T + 2ʃ1 R dv/v
Or, s2 – s1 = c2 In T2 / T1 + R In v2 /v1
we also have Tds = dh udp
ds = dh / T– udp /T
= cpdt / t – R dp /p
Equivalent equations for entropy change:
Entropy change between two states 1 – 2 can also be written as
s2 – s1 = cp In T2 / T1 –R In P2 / P1
As cp – cu = R, equation (9 .19) can be written as
s2 – s1 = cp In T2 / T1 – cp In P2 P1 + c2 In P2 / P1
Or, s2 –s1 = cp In P1 T1 / P2 T2 + c2 In P2 / P1
Also, s2 – s1 = cp, in v2 / v1 + c2In p2 / p1
Or, s2 – s1 = cp, in v2 / v1 + cv In p2 / p1
We can use equations (9.18), (9.19), (9.20) for computing the e::1tropy change betweentwo states of an ideal gas.
Links of Previous Main Topic:-
- Open system and control volume
- Conversion of work into heat
- Introduction to carnot cycle
- Clausius inequality entropy and irreversibility introduction
- Ideal gas or perfect gas
- Ideal gas or perfect gas
- Specific heats internal energy and enthalpy of an ideal gas
Links of Next Mechanical Engineering Topics:-
- Reversible adiabatic process
- P v and t s diagrams for pv c
- Equations of state
- Law of corresponding states
- Introduction about air standard cycles
- Properties of pure substances introduction
- Vapour compression refrigeration cycle introduction
- Basic fluid mechanics and properties of fluids introduction
- Fluid statics introduction
- Manometers measurement pressure
