Rankine Notes

Mon Dec 13

• The boiler pressure MUST be more than the condenser pressure!
• Steam Turbines only work with Steam - Try boiling the water!
• The condenser pressure MUST be less than the boiler pressure!
• Negative pressures are a bit difficult!
• The reheater pressure MUST be less than the boiler pressure!
• The reheater pressure MUST be more than the condenser pressure!
• The feed heater pressure must be below the critical pressure.
• The feed heater pressure MUST be less than the boiler pressure!
• The feed heater pressure MUST be more than the condenser pressure!
• The boiler temperature and pressure may be varied between 0 and 800 degrees Celsius and 0 and 100 MP
• The condenser pressure or temperature may be varied but since the program assumes that the fluid leaving the condenser will be saturated these are not independent.
• The efficiencies of the turbines may be changed to investigate the consequences of irreversibilities in real cycles. The efficiency of the pumps cannot be changed since it has negligible effect on the overall cycle efficiency.

• ~tpl/matlab/rankine.m has taken about 9 hours. No maths, but diagrams/interface drawn. Scrollbars for input?

Thu Dec 16

• Dealing with continuation lines
• Dealing with comments
• Replacing .GT., .OR., etc
• Removing THEN. Replacing END IF by END
• Dealing with single-line IF statements
• Putting commands into lower case
• Removing variable declarations
• Removing DOUBLE PRECISION in function definitions
• Changing function return syntax
• Dealing with call by reference
• Replacing GOTO
• Using switch instead of multiple IFs
• Replacing **
• Replacing else if by elseif
• Adding semicolons

Mon Dec 20

Tue Dec 21

Tue Jan 4

Wed Jan 5

Globals

• Y(14) IS MASS THROUGH GIVEN POINT PER KG THROUGH POINT 7 - i.e. flow?
• P(14) is pressure
• T(14) is temperature (in K)
• V(14)
• H(14) Enthalpy (I assume)
• S(14) - entropy?
• X(14) is dryness
• TXT(14) IS THE NAME OF EACH POINT ON THE CYCLE
• NIS(3) - TURBINE ISENTROPIC EFFICIENCY (0-1)
• TWORK(3) - turbine work
• PWORK(3) - pump work
• EFFY - CYCLE EFFICIENCY
• EFFZ - ORIGINAL EFFICIENCY
• FDHEAT - number feeder heaters (one less than the number of pumps)
• TSAT
• QB - Boiler heat
• QC - Condenser heat

T(1)=303.15;
T(7)=773.15;
P(7)=1.5D7;
P(2:6)=P(7);
P(1)=psat(T(1));
P(8)=P(1);

X=     0      0      0      0      0      0      1 0 0 0 0 0 0 0
S= 436.5  436.5  436.5  436.5  436.5  436.5 6348.7 0 0 0 0 0 0 0
T=303.15 303.49 303.49 303.49 303.49 303.49 773.15 0 0 0 0 0 0 0
P=0.0004 1.5000 1.5000 1.5000 1.5000 1.5000 1.5000 0.0004 0.0004 0.0004 0.0004 0.0004 0 0
EFFY =0.4346
TWORK(1)=1.3927e+06
PWORK(1)=1.5012e+04

• Fix the bugs (the values in the 8th position are wrong)
• Test other configurations from the command line (easy?)
• Display output values in the GUI (done for the state-points)
• Allow input via the GUI (awkward dealing with invalid input?)
• Make the graph work

Thu Jan 6

• A graph is displayed, but only portions of it are correct.
• Most output values (including the correct rankine efficiency) are now displayed
• There's a problem in betak; it's sometimes called with THETA = 1 which causes a "divide by zero" condition.

I've archived the current version into ~/matlab/rankine1.

One reheater

The first run for one reheater produced

Two reheaters

The first run for 2 reheaters produced

(which took 3 more hours)

Next do a similar thing for pumps. Alas, it gets stuck in a while loop in rkcalc when feed pumps added. Also I need to remove unwanted output-table items when the table's redrawn.

Fri Jan 7

• Errors of the order of 0.01% - Matlab works in double precision. I don't know whether all the Fortran does
• Errors where values are wrongly 0 - How can so much be right if the Temperatures are sometimes so wrong? Maybe T is reset to 0 late in the calculations. Errors so far are at points 8, 10 and 12 - probably not a coincidence.
• Resetting Errors? - adding then removing 2 turbines doesn't return the system to the initial conditions - rankine efficiency becomes 5.85%

• Turbine efficiency, and boiler/condenser conditions can now be changed in the GUI (but it took an hour - callback ignorance). Previous efficiency shown.
• Unwanted output-table items removed (sub-optimally) when the table's redrawn.
• I'd only partly converted valph, valph3, valph4
• I'd converted a fortran 'CONTINUE' loop wrongly in rkcalc. I can now add feed heaters.

The new program gives

Four hours work today.

Tue Jan 11

• Correcting the calculations - no improvement recently.
• Correcting the graph - haven't looked at this recently, given that the graph depends on the calculations
• Correcting the addition/removal of pumps and turbines so that they don't have to be added/removed in sequence
• Tidying up the layout (easy!)
• Checking the validity of user-input (easy!)
• Improving the redraws so that existing objects aren't removed/created, only changed and moved.

Wed Jan 12

• In the original RKPLOT there's

        DO 10 I=1,21
          ...
          TEMP=(647.3D0-273.15D0)/20.*(I-1)+273.15D0
  

  In fortran or matlab is there ever a risk of the multiplication being done before the division, hence leading to division by 0?
• Though the original program doesn't compile any more, the numerical part does (with pkc's help). It's in ~tpl/SRC/rankine. I'm now going to compare intermediate values in the old and new programs. valpt gives the same results in both programs.

Thu Jan 13

• 1 turbine with 1, 2 or 3 pumps work ok - all values match those from the original program.
• I've added feedheater/reheater information to the screen, with callbacks so that the information can be changed.
• I've re-organised the screen so that there's no overlapping

Total now 34 hours.

Thu Jan 14

• I've been trying to get the graph right. The old and new programs both produce the same numerical answers in the graphs section, but produce difference graphics when there are coords with value -1.
• psat and betak are both suspect in their handling of singularities

Mon Jan 17

• Checking that things are reset when reheaters/feedheaters removed
• Dealing with possibility that Turbine 2 might be removed before Turbine 3, etc
• The Graph's wrong. I'll worry about that today again...
• Tidying up the Info window. Adding the original copyrights to the steamlib files.
• Testing...

• For I=1,21 and drynes=0, TEMP=(647.3-273.15)/20.*(I-1)+273.15. Then PRESS=PSAT(TEMP) is calculated and VALPT called. The resulting (ENTROP, TEMP) values are used as line coordinates - 20 lines
• The same is done for drynes=1 - 20 lines
• Then with PRESS=1000, TEMP=TSAT(PRESS) and drynes=0, VALPT called. It's called again with the same values except that drynes=1. A line is drawn between the (ENTROP, TEMP) values returned.

The corresponding values in the new programs are

I T PRESS ENTRP, drynes=0

1 2.731500e+02 6.108006e+02 -1.543959e-01

2 2.918575e+02 2.155952e+03 2.778160e+02

3 3.105650e+02 6.417191e+03 5.374847e+02

4 3.292725e+02 1.660731e+04 7.820055e+02

5 3.479800e+02 3.827555e+04 1.013397e+03

6 3.666875e+02 8.007477e+04 1.233302e+03

7 3.853950e+02 1.544147e+05 1.443196e+03

8 4.041025e+02 2.779209e+05 1.644420e+03

9 4.228100e+02 4.716732e+05 1.838178e+03

10 4.415175e+02 7.612499e+05 2.025554e+03

11 4.602250e+02 1.176635e+06 2.207551e+03

12 4.789325e+02 1.752060e+06 2.385144e+03

13 4.976400e+02 2.525829e+06 2.559347e+03

14 5.163475e+02 3.540202e+06 2.731280e+03

15 5.350550e+02 4.841373e+06 2.902259e+03

16 5.537625e+02 6.479718e+06 3.073956e+03

17 5.724700e+02 8.510698e+06 3.248717e+03

18 5.911775e+02 1.099738e+07 3.430239e+03

19 6.098850e+02 1.401656e+07 3.625275e+03

20 6.285925e+02 1.767206e+07 3.625275e+03

21 6.473000e+02 22120000 0

I T PRESS ENTRP, drynes=1

1 2.731500e+02 6.108006e+02 9.157729e+03

2 2.918575e+02 2.155952e+03 8.697428e+03

3 3.105650e+02 6.417191e+03 8.307432e+03

4 3.292725e+02 1.660731e+04 7.973921e+03

5 3.479800e+02 3.827555e+04 7.685970e+03

6 3.666875e+02 8.007477e+04 7.434871e+03

7 3.853950e+02 1.544147e+05 7.213626e+03

8 4.041025e+02 2.779209e+05 7.016532e+03

9 4.228100e+02 4.716732e+05 6.838853e+03

10 4.415175e+02 7.612499e+05 6.676575e+03

11 4.602250e+02 1.176635e+06 6.526241e+03

12 4.789325e+02 1.752060e+06 6.384850e+03

13 4.976400e+02 2.525829e+06 6.249722e+03

14 5.163475e+02 3.540202e+06 6.118263e+03

15 5.350550e+02 4.841373e+06 5.987601e+03

16 5.537625e+02 6.479718e+06 5.854169e+03

17 5.724700e+02 8.510698e+06 5.713436e+03

18 5.911775e+02 1.099738e+07 5.559689e+03

19 6.098850e+02 1.401656e+07 5.379245e+03

20 6.285925e+02 1.767206e+07 5.379245e+03

21 6.473000e+02 22120000 0

(1.060405e+02 2.801327e+02) (8.976668e+03 2.801327e+02)

Problems are reported for the i=21 values - "problem in betak, Divide by zero. Theta=1"

2 issues

• Note that the final TEMP value in the fortran is 647.300048828125 whereas the matlab equivalent produces exactly 647.3. The fortran PSAT routine begins with

        IF (TEMP.LE.647.3D0)
  

  So the fortran and matlab loop arithmetic produce different values for TEMP and hence for PRESSURE, but matlab's PRESSURE value seems viable. Besides, the ENTROP value is being used for plotting and that's the same in both versions. So why isn't the 0 ENTROP value causing trouble when used as an x coord in the fortran?
• The ENTROP value for I=19 and I=20 are the same in the matlab version, but not the fortran version.

Tue Jan 18

Found the bug - a missing "e-8". It's time to install. 3 hours today. 47 hours to produce this first release. 6034 lines of Fortran.

Thu Jan 27

Wed Feb 2

         IF (RHT.EQ.1) THEN
            IF (REHEAT.EQ.0) THEN
              P(8)=P(1)
              P(9)=P(1)
            ELSE
              P(8)=P(10)
              P(9)=P(11)
              T(9)=T(11)
              P(10)=P(1)
              P(11)=P(1)
            END IF
         ELSE IF (RHT.EQ.1) THEN
            P(10)=P(1)
            P(11)=P(1)
         END IF