Chemical Engineering Thermodynamics

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


Terms to acknowledge[edit]

  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[edit]

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