Chemical Engineering Thermodynamics

Thermodynamics is the science of relationship between heat work and the properties of the system involved.

Terms to acknowledge

1. Process - changes that a system undergoes from one equilibrium state to another
2. Cyclic Process - process which returns the system to the initial value at completion
3. Isothermal Process - change in system at constant temperature. It is often necessary to exchange heat with surroundings to maintain constant temperature.
4. Isobaric Process - change in system at constant pressure
5. Isochoric (Isometric) Process - change in system at constant volume
6. Adiabatic Process - process in system without heat exchange with surrounding. Q=0

Thermo variables

1. State variables - macroscopic quantities defining condition of a system such as temperature, pressure, mass

2. Path variables - value of path taken by the system between 2 state such as heat and work

Work (W)

• the energy transferred associated with a force acting through a distance: dW = F. dL
• also called the PdV work when above equation is integrated.
• enable us to find work associated with expansion or compression of a path

[ Sign of convention depends on authors, some uses +W when work is done by system on surroundings and -W when work is done on system by surroundings while others versa-wise; in this chapter, the former is used.]

Heat (Q)

• energy type which is transferred due to a temperature difference
• exchange in system and surroundings which would result in temperature or phase change.

Sign of convention: +Q when heat is added into the system ; -Q when heat is removed from the system