EBSILON®Professional Online Documentation
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Line connections |
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1 |
Entry 1 |
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2 |
Entry 2 |
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3 |
Outlet |
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4 |
Switch signal 1 or 2 |
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General User Input Values Physics Used Displays Example
Depending on the comparison of two thermodynamic values, the mass flow can be transmitted either from entry 1 or entry 2 to the exit 3.
All the 5 thermodynamic values P/T/H/M/Q can be comparison values.
IN4 is the control value for the switch entry corresponding to the user entryFTS. The component transmits the mass flow M1 or M2 to M3. Depending upon the results of the comparison of the two thermodynamic values, either M1 or M2 is transmitted. These comparison values are the physical values IN4 for the switch entry (line 4) and the specification value DVAL. The table given below shows the comparison conditions.
Delayed Start of the Check of the Switching Criterion:
As greater fluctuations may occur at the beginning of the iteration, there may be frequent switchover procedures at the beginning of the iteration.
To prevent this, it is now possible to specify in specification value FACT from which iteration step onwards the switching criterion is to be checked. Previously this was fixed to the 11th iteration step.
Note: Prevention of Frequent Switchover Processes
To prevent frequent switchover processes during the iteration, there is now a specification value ITSTEP that specifies for how many iteration steps after a switchover procedure no further switchover will be carried out.
Display Formats :
Three-way valve: The two inlets can not only be arranged opposite each other but also in a 90° angle towards each other. (see Component Displays).
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Transmission from ---> to |
FDC |
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1 |
-1 |
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M1 ---> M3 M2 ---> M3 |
IN4 <= DVAL IN4 > DVAL |
IN4 > DVAL IN4 <= DVAL |
In rare cases (when the solution is close to the threshold value) it can happen that the convergence of the iteration procedure deteriorates because component 49 switches continuously. In this case the convergence can be improved by specifying a hysteresis in the specification value HYST. The value of HYST, however, should be selected as small as possible as the result in the range ±HYST becomes unpredictable.
This hysteresis only refers to the behaviour during the iteration. It has nothing to do with a chronological sequence.
There is a input value FSPECX. It allows defining on which pins a composition is to be specified. However, this flag can only be used if the material equations are integrated into the equation system. (Model options ? Simulation ? Iteration, Level of integration of material equations)
In addition to mass flow rates, enthalpies and pressures also calorific value and material composition are directly involved in the matrix solution method. The result was an improvement of convergency in some cases, but a worsening in other cases.
Therefore, this feature will not be used by default. If anyone likes to test it, you may activate it by setting the level of integration of material equations.
Similar components:
Component 36 (signal transmitter type 1):
Unlike component 48, the output signal 3 cannot be selected from the two inputs, but instead is taken directly from the signal entry. Like component 48, the input signal can either be the related physical input signal or a characteristic line value. This is determined with the physical value as abscissa. The transferable input signal is not multiplied with the proportional factor, if the transmission is done with a characteristic line.
Component 48: (switch):
Depending on the comparison of two thermodynamic values, a signal value can be transmitted either from entry 1 or entry 2 to exit 3. All the 5 thermodynamic values P/T/H/M/Q can be comparison values. An index of function defines, whether the comparison takes place between the signal entry 4 and the decision value set to specification value or directly between the two signal entries 1 and 2. For every signal entry, an index of transmission defines whether the related physical value of the signal entry is transmitted multiplied with a proportionality factor or a characteristic line value.
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FTS |
Type of Switch Like in Parent Profile (Sub profile option only) Expression =1: Pressure =2: Temperature =3: Enthalpy =4: Mass flow =5: Power/heat flow |
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DVAL |
Decision value =1 |
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FDC
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Decision criteria Like in Parent Profile (Sub profile option only) Expression = 1: M1->M3 if IN4<=DVAL, else M2->M3 =-1: M1->M3 if IN4>DVAL, else M2->M3 |
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HYST |
Hysteresis (use only in case of convergency troubles) 0 |
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FACT |
Iteration step when evaluation of decision criteria is starting (default value: 11) |
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ITSTEP |
Minimum number of idle iteration steps between two switches (default value: 0) |
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FSPECX |
Material-equation handling Like in Parent Profile (Sub profile option only) Expression =0: Any given =1: Pins 1 and (2 or 3) given =2: Pins 2 and (1 or 3) given =3: Pins 3 and (1 or 2) given =12: Pins 1 and 2 given =13: Pins 1 and 3 given =23: Pins 2 and 3 given |
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Transmission from ---> to |
FDC |
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1 |
-1 |
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M1 ---> M3 M2 ---> M3 |
IN4 <= DVAL IN4 > DVAL |
IN4 > DVAL IN4 <= DVAL |
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Display Option 1 |
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Display Option 2 |
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Display Option 3 |
Click here >> Component 49 Demo << to load an example.
