Q. The jacket of my vessel responds slower/faster than the simulation in the heating/cooling program. What should I do?
A. Release three has a new feature that allows you to “tune” your simulation. Right click on the picture of the vessel and select tuning. The value acts as a gain although, the magnitude entered will not be the same as your control system.
Q. There are error numbers listed in the instruction book, but there is no number listed in the message box. How do I find these numbers?
A. Select one of the errors with the mouse and a “hint” will show up giving you the error number.
Q. There is a “Brine” included in the jacket fluids, what is it?
A. The brine is intended to be a 23% (by weight) calcium chloride solution. Different solutions of brine behave in a similar fashion but you should enter the data for the brine in use in your application. It is advisable to review all the data you use in a simulation to ensure that it is accurate and agrees with the system that you are modeling.
Q. There is a warning in the instruction manual that the correlation coefficient may not be mathematically correct. If it’s not correct, why are you using it?
A. Different curves are derived by minimizing their appropriate error functions. The least squares linear correlation minimizes the square of the sum of the deviation of the data point from the average. The function that is minimized for an exponential curve, however, is the square of the sum of the deviation of the natural logarithm from the natural logarithm of the average. Since there is a different optimizing function, there is a different (mathematically correct) correlation coefficient that is a measure of this optimization.
The reason that we are using the same correlation coefficient for all the curves is two fold:
1) In this way, the fit of the curve to the data can be compared with different types of curves. If you wish to determine which curve is better for your data, exponential or power curve, you need the same basis for correlation coefficient for this decision.
2) Not all curves are determined using least a squares curve fit method, so an appropriate correlation coefficient may not be available.
Q. The picture of the vessel fills while the simulation is running, but nothing is being added. Why?
A. If you are heating the vessel and the density is entered as a linear function then the vessel is “filling” as a result of the lower density of the liquid at higher temperatures. The program constantly calculates the current volume of the vessel including additions and removals and updates the picture while the simulation is running.
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