1. Chem. Eng. Thermodynamics (TKK-2137)
16/17 Semester 3
Chem. Eng. Thermodynamics (TKK-2137)
Instructor: Rama Oktavian
Office Hr.: M.10-15, Tu , W , Th , F

2. Outlines 1. 1st law thermodynamics 2. Energy balance for closed system
3. The phase rule
4. Energy balance for open system

3. 1st law thermodynamics Properties of matters:
Energy content of matters:
Other properties having the same unit as energy
Enthalpy, Free energy, etc.
Kinetic
Energy
Internal
Energy
Potential
Energy
Total Energy
of matters
NOTE: Heat and Work are energies exchanged between a system and its
surrounding, not properties associated with matters.

4. 1st law Thermodynamic Work (W)
Work can be followed by volume change of fluid (ex. Compression of a gas by a piston)
Total volume gives total work
Work per unit mass or mole
(-) shows that fluid compression is positive work W+

5. 1st law Thermodynamic Heat (Q)
Heat moves from object with higher T to object with lower T
Temperature difference is driving force of heat flow
W & Q are path variables
Path variables only have meaning when exchange between a system/substance and surroundings
A substance does not contain a certain amount of work or heat

6. what is the relationship between the various forms of energy?
1st law thermodynamics
Kinetic Energy(Ek)
Potential Energy(Ep)
Internal Energy(U)
We will focus on 5 forms of energy
Question:
what is the relationship between the various forms of energy?

7. 1st law Thermodynamic Total energy is constant DEk, DEp, DU Q W
-DE(surrounding)
DE(system) ＋ +
DE(system) + DE(surrounding) = 0
Mathematical formula

8. 1st law Thermodynamic Closed system Thus:
closed when no mass passes the boundary
Thus:
1st law thermodynamic for closed system:

9. ? 1st law Thermodynamic Closed system : state variable
: path variables
For closed system
Change from state 1 to state 2 with 2 different paths P T
P1,T1
P2,T2
What is the value for Q & W for each paths ?

10. 1st law Thermodynamic
Closed system

11. 1st law Thermodynamic Reversible process No-friction No turbulence
Always in equilibrium
Valid only for reversible proses
Reversible work is ideal work
1st law:

12. 1st law Thermodynamic Constant volume process Therefore
Heat transferred from or to system is equal with the value of internal energy change

13. 1st law Thermodynamic Enthalpy Constant pressure process:
Heat transferred from or to system is equal with the value of enthalpy change

14. 1st law Thermodynamic Heat capacity State variable Constant-P process:
For constant P process
State variable
For constant V process
Constant-P process:
Constant-V process:

15. 1st law Thermodynamic
Rework
Example 2.9
Example 2.10

16. The phase rule Gibbs phase rule where: F = degree of freedom
The number of maximum variables that must be specified or fixed to determine the other variables
= number of phase
Phase = a homogeneous region of matter
N = number of component
For pure substance (N = 1), minimum F = 0

17. The phase rule
Gibbs phase rule

18. Energy balance for open system
1st law:
DE(system) + DE(surrounding) = 0
Every unit of mass contains energy:
Total energy :

19. Energy balance for open system
Total energy in the system can change due to accumulation or loss:
Therefore:
(influent)
(effluent)

20. Energy balance for open system
Work: can be generated by flow work in and out (Wf) and shaft work (Ws)
influent
effluent
Remember:

21. Energy balance for open system
1st law thermodynamic for open system
effluent
influent
General process:
Steady state:
One inlet and outlet:
Rate of energy
Rate of energy per mass or mole

22. 1st law Thermodynamic for open system
Rework
Example 2.15
Example 2.16

23. Thank You !