AixLib.Fluid.Movers.Compressors.UsersGuide.Approaches.IsentropicEfficiency

# .AixLib.Fluid.Movers.Compressors.UsersGuide.Approaches.IsentropicEfficiency

Isentropic Efficiencies

## Information

Generally, two kinds of calculation approaches can be identified: A polynomial and a power approach. A generic polynomial approach is presented below:
`ηise = corFact * sum(a[i]*P[i]^b[i] for i in 1:nT)`
A generic power approach is presented below:
`ηise = corFact * a * product(P[i]^b[i] for i in 1:nT)`
All isentropic efficiency models presented in this library are based on a literature review. Therefore, the variable `corFact` allows a correction of the isentropic efficiency if the general modelling approach presented in the litarature differs from `ηise = (houtIse - hinl) / (hout - hinl)`.

#### Common model variables

Calculation procedures presented in the litarture have some variables in commen and these variables are presented below:

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Type | Name | Comment
--- | --- | ---
input | `epsRef` | Ratio of the real and the ideal displacement volume
input | `VDis` | Displacement volume
input | `piPre` | Pressure ratio
input | `rotSpe` | Rotational speed
input | `staInl` | Thermodynamic state at compressor's inlet conditions
input | `staOut` | Thermodynamic state at compressor's out conditions
input | `TAmb` | Ambient temperature

#### Polynomial isentropic efficiency models

Actually, three polynomial approaches are implemented in this package. To add further calculation procedures, just add its name in AixLib.Fluid.Movers.Compressors.Utilities.Types and expand the `if-structure` defined in AixLib.Fluid.Movers.Compressors.Utilities.IsentropicEfficiency.PolynomialIsentropicEfficiency.

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Reference | Formula | Refrigerants | Validity `ncompressor` | Validity `Πpressure`
--- | --- | --- | --- | ---
DarrAndCrawford1992 | `ηise = a1 + a2*n + a3/ρinlet` | R134a | `40 - 75` | `3 - 10`
Karlsson2007 | `ηise = a1 + a2*π + a3*π^2 + a4*n + a5*n^2` | R407c | `No information` | `No information`
Engelpracht2017 | `ηise = a1 + a2*n + a3*n^3 + a5*π^2` | Generic model | `0 - 120` | `1 - 10`

#### Power isentropic efficiency models

Actually, one power approache is implemented in this package. To add further calculation procedures, just add its name in AixLib.Fluid.Movers.Compressors.Utilities.Types and expand the `if-structure` defined in AixLib.Fluid.Movers.Compressors.Utilities.IsentropicEfficiency.PowerIsentropicEfficiency.

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Reference | Formula | Refrigerants | Validity `ncompressor` | Validity `Πpressure`
--- | --- | --- | --- | ---
MendozaMirandaEtAl2016 | `ηise = a1 * π^b1 * (nref/n)^b2 * (n^3*Vdis/dhise^1.5)^b3 * (1/((Tinl+ToutIse)/2-Tout))^b4` | R134a,R450a,R1324yf,R1234ze(E) | `0 - 50` | `1 - 6`

## Revisions

- October 19, 2017, by Mirko Engelpracht:
  First implementation (see issue 467).

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