EBSILON®Professional Online Documentation
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Measurement value input |
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General User Input Values Physics Used Displays Example
For the simulation, component 46 is similar to component 33 (start value). But instead of setting a bundle of values like component 33 does, here only one measured value is taken as start value. As compared to component 33, however, there are more possibilities for selecting the type of the user input value, see the specification value FTYP in the specifications table given below. To use the component 46 in the simulation, the flag FFU must be "on" and the flag must be set to "always active". The specification parameters relevant for the validation (MCONF, WMV, FIND, ICONF) do not play any role in the simulation.
For validation, only component 46 can be used. Values specified via component 33 are not validated, but instead retain their permanent values. For the validation, a relative weight (WMV) or a confidence interval (MCONF) must also be specified for the measuring point along with the measured value (MEASM) itself. The specifications needed depend upon the selected validation method.
In the power plant it is often of interest not to correlate the deviation with the respective measured value, but with the upper range value. For this, there is a new result value LIMDEV that usually (if all values are positive) is calculated as follows:
LIMDEV = (MEASM &endash; RESULT) / ULIM
In the case of measured values that can also adopt negative values, however, this definition does not make that much sense. You realize this by specifying a lower limit LLIM < 0. In this case, not the upper range value ULIM but the measuring range, i.e. the limit between the upper and lower limit, is used for correlation:
LIMDEV = (MEASM &endash; RESULT) /(ULIM-LLIM)
Specifying the calorific value (FTYP=6)
For specifying the calorific value (FTYP=6) the user can select (FNCVREF) if the reference temperature for the calorific value is to be adopted from the model settings or if it is to be specified in the component itself in the specification value TNCVREF.
Note : specification value MCONF
Until the specification value MCONF was introduced in 2002, the confidence interval was calculated from the weight WMV (=1.96/WMV) for the VDI 2048 validation. In Release 11,
this automatic determination of MCONF from WMV is deactivated because it will lead to unexpected results if MCONF has been left blank unintentionally. An error message
“Illegal value for MCONF” is issued. In this case a value for MCONF must be entered manually. On entering the expression “1.96$.WMV“ at MCONF, the previous results should
be reproducible.
Specification of the relative humidity of the air
The humidity can be specified with component 46 (measured value).
The specification of humidity is used in the programme as follows:
This restricts component 46 as humidity specification to lines where the enthalpy is given with components of type 1 or 33 by specification of the temperature. However, this type of humidity specification has a negative effect on convergence (fluctuations in enthalpies and water content) and is therefore not recommended.
It is therefore recommended to specify the relative humidity in component 1 or 33 under "Substance proportions". It should be noted that
Temperature specification in the wet steam region
In the power plant, quite often there are temperature measurements in the wet steam region. These measurements cannot be used to determine the enthalpy as this quantity is depending on the steam content in the wet steam region. As the temperature is determined by the pressure in a unique way, the temperature measurement can be used as replacement (or addition, in case of validation) for a pressure measurement. To use this feature, you have to set FTYP to "pressure from wet steam temperature" (32, see below).
Specification of a material concentration
Compositions can be specified via boundary values and start values respectively (Component 1 and 33 respectively) or via measured values (Component 46).
The specification via measured values is required when a validation of the composition is to be carried out.
The interaction between the two options for specification used to be relatively complicated. As the total of all substances has to result in 1, not all substances could be specified via measured values, but one still needed a degree of freedom for the standardization. Usually, the greatest fraction in the component Boundary value and Start value respectively was taken for this.
When the complete composition is specified via a boundary and start value, there are no modifications in the specification. In this component it is possible to check immediately whether the total of all substances results in 1.
If that is not the case, an error message will be generated.
If you click with the right mouse button on a number of the composition, there are the following scaling options:
When specifying via measured values, one measured value is to be placed on the line for each occurring substance. In addition, one boundary and start value respectively is required on the same line in order to provide the additional information that cannot be defined via measured values (e.g. the coal type or cp coefficients for the user-defined fluid). In this start value one also needs to specify that when integrating the material equations into the equation matrix, equations with the value 0 are provided for the unspecified substances (otherwise one would have to set a measured value with the value 0 for each substance that is not contained). If the total of all measured values does not result in 1, an error message will be output.
Specification of pseudo values
Component 46 also enables the specification of values, which cannot be handled at all directly in EBSILON®Professional, such as current strengths. These can then be treated like normal measurement values on the outside (especially in the context of an EPOS-system). Internally, they can only be used for a pre-processing in the EbsScript. It is recommended to assign such values on a separate auxiliary line and to disable them. When one activates such values, they are interpreted as enthalpy. The values affected by this can be seen in the listing for FTYP given below.
For pseudo measuring points (FIND > 0), the RESULT value is always used, as the previous behaviour was inconsistent (only for active measuring points the RESULT value was used, for switched off ones the MEASM value.
Status of a measuring point
After doing a calculation (validation or simulation), a status FSTAT is assigned to each measuring point, which can have the following values:
0 not defined
1 valid for validation
2 always valid
3 valid with warning (for validation)
4 valid with warning (always)
5 manually deactivated
6 automatic deactivated
7 Measured value lies outside the confidence interval of the validated value
The automatic deactivation takes place for redundant measuring points during validation, if the deviation between the measuring value and the validated value exceeds the double of the specified confidence interval. In such a case, a warning message is given.
Further details about the result values of this component are described in the chapter Validation Results.
Super Cooling and overheating define the enthalpy in such a way that the corresponding temperature is below (in the case of super cooling) or above (in the case of overheating) the boiling temperature (for water / steam and 2-phase fluid) or the dew point temperature (for air / flue gas) by the specified amount.
For CO2, below 5.2 bar the sublimation curve instead of the boiling curve is taken as a basis.
"Standard“ quantities
In practice, certain quantities are often related to “standard conditions“; depending on the context, different standards are used.
The options for determining the standard conditions (to specify quantities related to standard conditions ) have been further extended :
A combination of reference pressure and reference temperature is defined by means of the flag FNORM. Besides the six prefabricated combinations
Adopting the reference values from the general settings is not reasonable because other results might be generated on another computer.
Reference pressure at off-state Measured value input :
The reference pressure (the reference variable for relative pressures) is defined by means of a Measured value input (Component 46) with FTYP=13. This Measured value input has to be placed on a line on which this value was also accepted as pressure. If no line was required where this pressure existed, an auxiliary line had to be put into the model for this purpose.
It is possible to specify the reference pressure without this value being taken over on a line.
This is done by setting the flag FFU to “Off” in the reference pressure measuring point. “Off“ then means that the value is not adopted on the line. The specified value, however, is taken over as reference value anyway.
If, however, no value is entered, the pressure is taken over as reference value from the line as previously. The same applies to active Measured value inputs.
The flag FNORMW decides if for determining the standard volume only the dry fraction of the gas is to be considered, or if the water fraction is to be taken along.
The flag FNORMO2 enables a conversion to a reference oxygen concentration. There are the following variants:
• FNORMO2=0: Actual O2 concentration is kept, whereby this concentration refers to the dry or humid flue gas depending on the setting
of the flag FNORMW.
• FNORMO2=1: the reference concentration is taken over from the model settings, whereby this concentration refers to the dry or humid flue gas depending on the
setting of the flag FNORMW.
• FNORMO2=2: the reference concentration is taken from the component specification value O2REF, whereby this concentration refers to the dry or humid flue gas
depending on the setting of the flag FNORMW.
• FNORMO2=3: : the reference concentration is taken over from the model settings, whereby this concentration always refers to the dry flue gas, independent of the
flag FNORMW.
• FNORMO2=4: the reference concentration is taken from the component specification value O2REF, whereby this concentration always refers to the dry flue gas,
independent of the flag FNORMW.
The flags FNORM, FNORMW, FNORMO2 refer exclusively to the standard volume. If the standard volume changes, there is of course a different value for the heating value per standard volume.
Example methane: the calorific value is 50015 kJ / kg.
At 1 bar, 15 ° C the density is 0.6696 kg / m³, i.e. 1 Nm³ = 0.6696 kg.
The calorific value per standard volume is 50015 * 0.6696 = 33490 kJ / Nm³.
At 1.01325 bar, 0 ° C the density is 0.71575 kg / m³, i.e. 1 Nm³ = 0.71575 kg.
The calorific value per standard volume is 50015 * 0.71575 = 35798 kJ / Nm³.
Wet bulb temperature
FTYP = 37
Previously, the wet bulb temperature could only be used in the indicator (Component 45) (FTYP=37), a specification was not possible.
That was changed. It is also possible with the measured value to specify the wet bulb temperature.
This defines the water content (as an alternative to the specification of the relative humidity of the air).
Density and specific volume:
Density and specific volume were only implemented for the value display (component 45), since the density and the specific volume result from the material data, and can not
be set via a measured value.
For standardization, however, the previous FTYP = 41 was also implemented in component 46 in FTYP = -41. Again, the conversion is done automatically.
FTYP = 44: Standardized volume flow takes place according to the setting: FNORM (see above), FNORMW (wet or dry) and FNORMO2 (see above)
The calculation of the normalized volume flow is carried out the following way:
1. All the water (XH2O) in the flue gas is maintained (FNORM = 0) or all the water (XH2O) is removed (if FNORMW = 1) and the composition normalized to 1 again.
2. Calculation of the specific volume VNORM under standardized conditions from the physical properties function V(P,T)
3. Calculation of the normalized volume flow VMN according to
VMN = D_DRY * VNORM,
where D_DRY is the mass flow after removal of the water.
For line types without composition (particularly also for water lines), the entire mass flow is taken as a basis.
This component is following new measurement types:
FTYP = 48: Angle The quantity “angle“ is internally treated as enthalpy.
FTYP = 49: Net calorific value (based on normalized volume flow) The normalized volume flow is set according to the specifications described above. For the NCV it is possible
to switch the definition of the reference temperature for the NCV using the flag FNCVREF. This can optionally be specified in the component (FNCVREF=0), or the model
setting is used (FNCVREF=1).
FTYP = 52: Normalized volume flow after simplified conversion (according to equation of state for ideal gases) Usually Ebsilon uses the complete physical properties functions
when converting to standard conditions. For example, possibly contained water can condense in the process. In the case of FTYP=52, the conversion is not effected
on the basis of the physical properties functions but according to the equation V/VNORM = (T/TNORM) / (P/PNORM),(see setting FNORM 0/1, see FTYP = 44) .
Furthermore, were added:
FTYP = 55: Power factor (cos(phi)), phi>1 assumed
FTYP = 56: Enthalpy with dimension of energy flow per area
FTYP = 57: Phase shift between voltage and current
FTYP = 58: Specific volume
Torque
On mechanical shafts, the torque M can be displayed and specified respectively (FTYP=59). It results from output Q and rotational speed F according to
M = Q / (2π*F)
Please note: To receive the torque in Nm in the formula, the output must be entered in W and the rotational speed in 1/s. When using the Ebsilon standard units
(Q in kW, F in 1/min), the following applies:
M [Nm] = (30000/π) * Q [kW] / F[1/min]
If the torque is specified (in the measured value), the shaft power is thus defined. It is then calculated by means of the rotational speed F according to
Q = 2π*F*M
In Ebsilon standard units, the formula is
Q [kW] = (π/30000)*F[1/min] *M[Nm]
Irradiation (energy per area) :
With FTYP=60 it is now possible to specify a value with the dimension “Energy per area” and have it displayed respectively. Internally, however, this variable is mapped onto
an enthalpy.
Gross calorific value
In FTYP=77 allows to specify the gross calorific value on a line (see"Specification of material properties").
Saturation factor
FTYP=78 serves to specify the “saturation factor“ that has been implemented for controlling the relative humidity to a value of 100 percent . It corresponds to the relative
humidity for values up to 100 percent. In the case of oversaturated air, it is the ratio of the total water to the water in the gaseous phase.
Pressure from the dew point temperature
FTYP=79 : With FTYP=79, the dew point temperature can be used to specify a pressure too. For fluids that consist of only one substance, this is identical with
FTYP=32 (“Pressure from boiling temperature“). In the case of mixtures, however, boiling point and dew point may differ from each other.
Molar Mass Flow
Now the molar mass flow can not only be used for the display but also as specification. With FTYP=87 in Component 46, the mass flow is set on a line according to the entered number of moles, at the composition that exists on the line in the respective iteration step.
If the molar mass flow is specified on a line whose composition changes over the course of the iteration, this will lead to changes in the mass flow and corresponding consequences for the convergence.
Pressure from boiling and dew point temperature for universal fluid
FTYP=32 and FTYP=79 can be used for streams of type „universal fluid” as well. In this case the boiling/dew point temperature of the partial stream with the highest
mass fraction is used.
This is reasonable if you have one main fluid and perhaps smaller admixtures that only have a negligible impact on the boiling or dew point. Otherwise, it is recommended to use a different library that is able to calculate the requested combination as a mixture.
Note : Specification of Frequency, Current, Voltage
The following measured value types are used for the specification with measured value inputs:
FTYP=15 for the current,
FTYP=16 for the frequency and rotational speed respectively,
FTYP=20 for the voltage,
FTYP=15, 16, and 20 were also available in older Ebsilon Releases, but were then mapped onto enthalpies.
Compatibility modes have been introduced to allow logic constructions from existing models to continue working; these are FTYP=-15, -16, and -20 that continue to be mapped onto dummy enthalpies. When loading a model created with Release 11 or older, measuring points with FTYP=15, 16, 20 are automatically shifted to -15, -16, -20, so that the measuring points provide the same equations as before. If required, the model can be revised accordingly in order to use the new options.
Insert Display-Fields:
When a measurement point is selected, the context command “Insert Display Fields” (right mouse button) allows to insert a text field with the name of the measurement point and two alarm fields with the measured and the calculated value. By default, the alarm conditions is a deviation of more then 5 % between measured and calculated value.
Comparison with component 45
Component 45 differs from component 46 in that it does not specify a value but just displays the calculated value. This is only a comparative value for the measuring value. Component 45 is an inactive component without any influence on the course of the simulation.
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FTYP |
Flag for the type of value Like in Parent Profile (Sub profile option only) Expression =1: Pressure (absolute)
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MEASM |
Measurement or start value
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MCONF |
Confidence interval of the measurement value (for validation as per DIN 2048) - See note (under "General") !
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FMCONF |
Flag to define the type of the confidence interval for MEASM Like in Parent Profile (Sub profile option only) Expression =0: absolute |
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PRMCONF |
Flag to specify the probability of MCONF 0.9 = 90% probability |
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WMV |
Relative weight of the measurement value in the validation (for standard EBSILON validation)
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FIND |
Index when using as pseudo measurement point for a specification parameter of another component. In case of the other component, the same value must be entered for the index in the field "IPS".
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ICONF |
Plausibility limit for measurement value (see Validations parameter)
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FFU |
Switch "AN" / "AUS" Like in Parent Profile (Sub profile option only) Expression =0: Measurement point is completely switched off =1: Measurement point is switched on (i.e. active based on FVAL) =4: Measurement point is switched on (active according to FVAL) in design mode and off in off-design mode. =5: Measurement point is switched off in design mode and on in off-design mode.
The mode =4 permits in case of a heat exchanger a temperature definition in the design case and a subsequent off-design calculation without changing the specification parameters. |
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FVAL |
Flag for using VAL
Like in Parent Profile (Sub profile option only) Expression =1: Value is considered only during validation. =2: Value is used in simulation and validation. |
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FVAR |
Flag to define the variable type Like in Parent Profile (Sub profile option only) Expression =0: no variable =1: normal variable =2: help variable |
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FSUBST |
Substance to be controlled Like in Parent Profile (Sub profile option only) Expression =0: nothing =1: N2 =2: O2 =3: CO2 =4: H2O =5: SO2 =6: Ar =7: CO =8: COS =9: H2 =10: H2S =11: CH4 =12: HCl =13: Ethane =14: Propane =15: n-Butane =16: n-Pentane =17: n-Hexane =18: n-Heptane =19: Acetylene =20: Benzene =21: C (elemental) =22: H (elemental) =23: O (elemental) =24: N (elemental) =25: S (elemental) =26: Cl (elemental) =27: Ash =28: Lime (Ca(OH)2) =29: deprecated: Water (liquid) (H2O) =30: Water (bonded) =31: Ash (gaseous) =32: NO =33: NO2 =34: NH3 =37: Methanol (CH3OH) =38: deprecated: Water (H2O) =39: Neon (Ne) =40: Dry Air
further material properties No. 41 - No. 2400
Further substances of a composition can be found on the surface of the value display default value "FSUBST" Obviously, or entering two to three significant letters of the desired material value is sufficient to obtain a targeted selection of material values.
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FNORM |
Flag to define a combination of reference pressure and reference temperature Like in Parent Profile (Sub profile option only) Expression =0: EBSILON default (1bar, 15°C) =1: DIN 1343 (1.01325bar, 0°C, often used for Nm3) =2: ISO 2533 (1.01325bar / 14,696 psia, 15°C / 59°F, often used for SCM (standard cubic meter) ) =3: DIN 1945 (1bar, 20°C) =4: 1bar, 0°C (use for line result MGNM3) =5: 1.01325bar, 20°C (German TA Luft) =6: 14.696psia, 60°F (often used for SCF( standard cubic feet )) =-1: Use measurement points for reference pressure and temperature =-2: Do not normalize but use actual pressure and temperature |
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FNORMW |
Flag to define treatment of water concentration Like in Parent Profile (Sub profile option only) Expression =0: Keep Actual water concentration ('wet') =1: Neglect actual water concentration ('dry') |
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FNORMO2 |
Flag to define scaling to reference O2 concentration Like in Parent Profile (Sub profile option only) Expression =0: Keep actual O2 concentration (no scaling) =1: Scale to molar O2 concentration from model settings =2: Scale to molar O2 concentration as specified in O2REF =3: Scale to dry molar O2 concentration from model settings =4: Scale to dry molar O2 concentration as specified in O2REF |
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O2REF |
Reference O2 concentration (molar) used for scaling |
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FNCVREF |
Flag to define reference temperature for net calorific value Like in Parent Profile (Sub profile option only) Expression =0: By specification value TNCVREF =1: By stream / model settings |
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TNCVREF |
Reference temperature for net calorific value |
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TABUNC |
Table uncertainty for VDI2048-Validation (only in case of explicit default): While validating as per VDI 2048 it is possible to include the uncertainties in the material value tables in the calculation. To do this, the checkbox " Consider the material value table uncertainties" must be checked in Model Settings under Validation. The standard deviation of the uncertainty for the calculation of enthalpy from pressure and temperature can then be entered for the temperature measurement point as specification value ”TABUNC”. |
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LLIM |
Lower limit |
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ULIM |
Upper limit |
The values LLIM and ULIM have no significance for the EBSILON®Professional-computing core, but can be used in EbsScript.
Generally, all inputs that are visible are required. But, often default values are provided.
For more information on colour of the input fields and their descriptions see Edit Component\Specification values
For more information on design vs. off-design and nominal values see General\Accept Nominal values
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All cases |
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FTYP=1: P1 = MEASM FTYP=2: T1 = MEASM FTYP=3: H1 = MEASM FTYP=4: M1 = MEASM FTYP=5: Q1 = MEASM FTYP=6: NCV1 = MEASM FTYP=7: XH2OG1 = MEASM FTYP=8: H1 = MEASM FTYP=9: H1 = MEASM FTYP=10: X1= MEASM FTYP=11: PHI1 = MEASM FTYP=12: Prel = MEASM P1=Pabs+Prel FTYP=13: Pref = MEASM P1=Pref FTYP=14-20: H1 = MEASM FTYP=21: VM1 = MEASM FTYP=22-25: determination of X for the substance identified by FSUBST FTYP=26: TRef = MEASM FTYP=27-31: H1 = MEASM FTYP=32: Tsat = MEASM FTYP=33: H1 = MEASM FTYP=34: T1 = Tsat (P1) - MEASM FTYP=35: T1 = Tsat (P1) + MEASM FTYP=36: P1 = 1.01325 * FTYP=37,38: does not set any value FTYP=39-41: H1 = MEASM FTYP=42,43: does not set any value FTYP=44: definition of material composition FTYP=45: H1 = MEASM FTYP=46: definition of material composition FTYP=47: H1 = MEASM
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Display Option 1 |
Click here >> Component 46 Demo << to load an example.
