The working substance is a phase-change (PC) fluid. That is, it can exist as a sub-cooled liquid, superheated vapor, or as a mixture of saturated liquid and vapor. Example:
R-134a vapor is compressed in a piston-cylinder device from a begin-state
to a finish-state. To find the work transfer if compression is assumed isentropic.
SL Model
Constant density
and
constant specific heats
(c_p=c_v=c)
characterize the solid/liquid (SL) model. Example:
A block of copper is heated from a begin-state to a finish-state. To find the heat transfer necessary for the process.
Gases:
PG Model
Obeys the ideal gas equation (pv=RT). Moreover, the specific heats are assumed constant. A perfect gas (PG) is a simplified ideal gas. Example:
Gaseous CO2 is compressed in a piston-cylinder device from a
begin-state
to a finish-state with no possibility of aphase change. To find the work transferred during the process.
IG Model
Obeys the ideal gas equation (pv=RT). Specific heats are temperature dependent; thus, the IG model is more accurate than the PG model. Example: Air is compressed in a piston-cylinder device from a
begin-state
to a finish-state with no possibility of a phase change.
RG Model
Based on the generalized compressibility chart (pv=ZRT), the real gas (RG) model can handle a large number of fluids with different phase compositions. But generality comes at the expense of accuracy. Example:
Gaseous CO2 is compressed in a piston-cylinder device from a
begin-state
to a finish-state with the possibility of phase change.
Binary
Mixtures
The mixture contains two gases, A and B, with its composition expressed in terms of the mass or mole fraction of gas-A.
PG+PG
Model
IG+IG
Model
RG+RG
Model
General
Mixtures
Mixture can contain
any number of species
from 1 to n (n>60).
n-PG Model
n-IG Model
Specific Closed Process and Its Governing Balance Equations
System
Animation of a uniform closed system going through a process. The color of the system is uniform, signifying its uniform state - a single state describing it at any instant. For specific examples of uniform closed processes, visit VT.Chapter-5 pages.
