Subsystems made of the same substance (H2O and H2O, Air and Air, etc.)
PC Model
SL Model
PG Model
IG Model
The system has two uniform sub-systems, each with the same working fluid (say, H2O and H2O). While the two sub-systems exchange energy, they maintain their individual identities as they do not mix. We will need two states, bA and bB, to describe the composite begin-state and two states, fA and fB, to describe the composite finish-State.
Example: Two tanks, one containing steam and the other containing liquid water are brought in thermal contact but not allowed to mix.
Subsystems made of different substances (NH3 and H2O, Iron and Steam, etc.)
PC Model and
PC Model
The system has two uniform sub-systems consisting of two phase-change fluids, say, H2O and NH3 (or H2O and H2O), which are not allowed to mix. Therefore, we will need four states, - bA, bB, fA and fB-states - to describe the non-uniform begin and finish states.
Example: A tank containing saturated steam is brought in thermal contact with a second tank containing superheated ammonia (no mixing). The bA and bB states, State-1 and state-2, are completely given. Suppose we are to find the temperature and the pressure in the tanks at equilibrium. For state-3 (fA state), enter m3=m1 and Vol3=Vol1. For State-4 (fB state) enter m4=m2 and T4=T3 (or, e4=e2+m1*(e1-e3)/m2+Q). Set up the process-analysis panel for the known value of W(=0) and an unknown Q (even if Q is given). Now guess T3 or x3 and Super-Calculate T4 and Q. Repeat with better guesses until Q=0 (or the given value).
SL Model and
SL Model
The system has two uniform sub-systems consisting of two blocks of solids, two liquids (different or identical), or a solid and a liquid, which do not exchange any mass at any time. The liquid has no possibility of a phase change allowing the use of the SL model. We will need two states, bA and bB, to describe the composite begin-state and two states, fA and fB, to describe the composite finish-State.
Example:A block of aluminum is brought in thermal contact with another block of copper. The bA and bB states, State-1 and state-2, are completely given. Suppose we are to find the equilibrium temperature and the entropy generated in the process. For state-3 (fA state), enter m3=m1, and leave T3 as an unknown. For State-4 (fB state) enter m4=m2 and T4=T3. Set up the process-analysis panel for the known value of W(=0) and an unknown Q (even if Q is given). Now guess T3 and Super-Calculate T4 and Q. Repeat with better guesses until Q=0 (or the given value).
IG Model and
IG Model
The system has two uniform sub-systems consisting of two perfect gases, identical or different (PG Models). While the two sub-systems exchange energy, they maintain their individual identities since they do not mix. We will need two states, bA and bB, to describe the composite begin-state and two states, fA and fB, to describe the composite finish-State. The property mass fraction, x_A, of gas A is set to 0 or 1 to select gas A or gas B as the working fluid. Note that two identical gases can be treated under the same framework (x_A will remain fixed as either 1, for gas A, or 0 for gas B).
Example: A cylinder contains two gases separated by a sliding piston, which is locked into its position. The bA and bB states, State-1 and state-2, are completely given. After the piston is released from its locked position, we are to find the final pressure and temperature. For state-3, enter m3=m1, and leave p3, T3 and Vol3 as unknown. For State-4 enter Vol4=Vol1+Vol2-Vol3, m4=m2, and p4=p3. After the process-analysis panel is set up for the known value of W(=0) and an unknown Q, guess p3 and Vol3, and Super-Calculate T4 and Q. Repeat systematically until T4=T3 and Q=0. In most problems, however, either p3 or T3 is supplied simplifying the iterative procedure.
PC Model and/or
SL Model
The system has two uniform sub-systems consisting of a solid (SL Model) and a phase change (PC Model) fluid. We will need two states, bA and bB, to describe the composite begin-state and two states, fA and fB, to describe the composite finish-State.;
Example: A block of hot copper is dropped into a water tank and the final temperature is the desired unknown with a possibility of phase change. Here, the bA and bB states, composed of the begin state of copper and water respectively, can be represented by State-1 and 2. The fA and fB states, similarly, can be represented by State-3 and 4, with T4 (entered as '=T3') left as an unknown. Set up the process analysis panel with W set to zero and Q set to unknown. In the iterative procedure, enter an estimate for T3 and Super-Calculate to evaluate Q. Repeat until Q is equal to the given value (zero for adiabatic system). Instead of guessing T3, x3 can also be adjusted if there is a possibility of phase change.
PC Model and/or
IG Model
The system has two uniform sub-systems consisting of a phase-change fluid (PC Model) and an ideal gas (IG Model). While the two sub-systems exchange energy, they maintain their individual identities as they do not mix. We will need two states, bA and bB, to describe the composite begin-state and two states, fA and fB, to describe the composite finish-State.
Example: Two tanks, one containing steam and the other containing air are brought in thermal contact.
IG Model and/or
SL Model
The system has two uniform sub-systems consisting of a solid or a liquid (SL Model) and an ideal gas (IG Model). While the two sub-systems exchange energy, they maintain their individual identities as they do not mix. We will need two states, bA and bB, to describe the composite begin-state and two states, fA and fB, to describe the composite finish-State.
Example:A block of hot copper is dropped into tank containing a gas at a known temperature and pressure. The final pressure and temperature are the desired unknown. Here, the bA and bB states, composed of the begin state of copper and air respectively, can be represented by State-1 and 2. The fA and fB states, similarly, can be represented by State-3 and 4, with T4 (entered as '=T3') left as an unknown. Set up the process analysis panel with W set to zero and Q unknown. In the iterative procedure, enter an estimate for T3 and Super-Calculate to evaluate Q. Repeat until Q is equal to zero (adiabatic system) or the given value.
Non-Mixing Closed Process by Non-Uniform Systems: Governing Balance Equations
System
Animation of a closed non-uniform system going through a non-mixing process. The begin-state is composed of two states bA and bB states (non-uniform). As heat or work (not shown here) is exchanged between the two subsystems, the overall system goes through a process. When equilibrium is finally achieved, two states -fA and fB states - are necessary to describe the finish state. In a non-mixing system there is no mass exchange among the subsystems. For specific examples of non-mixing closed processes, visit TEST.VT.Chapter-5 pages.
