AixLib.Fluid.Movers.Compressors.UsersGuide.Approaches.VolumetricEfficiency

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

Volumetric Efficiencies

## Information

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

#### 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 volumetric efficiency models

Actually, four 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.VolumetricEfficiency.PolynomialVolumetricEfficiency.

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Reference | Formula | Refrigerants | Validity `ncompressor` | Validity `Πpressure`
--- | --- | --- | --- | ---
DarrAndCrawford1992 | `ηvol = a1 + a2*n - a3*epsRef*(ρinlIse/ρinl-1) - a4*n*(ρinlIse/ρinl-1)` | R134a | `40 - 75` | `3 - 10`
Karlsson2007 | `ηvol = a1*Tinl*π + a2*π + a3 + a4*Tinl + a5*n + a6*n^2` | R407c | `No information` | `No information`
KinarbEtAl2010 | `ηvol = a1 + a2*π` | Generic model | `Generic model` | `Generic model`
ZhouEtAl2010 | `ηvol = 1 + a1 - a2*π^(1/κ)` | Generic model | `Generic model` | `Generic model`
Li2013 | `ηvol = ηvolRef * (a1 + a2*(n/nref) + a3*(n/nref)^2)` | R22,R134a | `30 - 120` | `4 - 12`
HongtaoLaughmannEtAl2017 | `ηvol = a1 + a2*(n/nref) + a3*(n/nref)^2 + a4*π + a5*(n/nref)*π + a6*(n/nref)^2*π + a7*π^2 + a8*(n/nref)*π^2 + a9*(n/nref)^2*π^2 + a10*pout + a11*(n/nref)*pout + a12*(n/nref)^2*pout - a13*pinl - a14*(n/nref)*pinl - a15*(n/nref)^2*pinl + a16*pinl*pout + a17*(n/nref)*pinl*pout + a18*(n/nref)^2*pinl*pout + a19*(n/nref)^3*pinl*pout + a20*(n/nref)^4*pinl*pout - a21*pinl^2 - a22*(n/nref)*pinl^2 - a23*(n/nref)^2*pinl^2 - a24*(n/nref)^3*pinl^2 - a25*(n/nref)^4*pinl^2` | Generic model | `Generic model` | `Generic model`
Koerner2017 | `ηvol = a1*π^b1` | R410a | `50 - 120` | `1 - 10`
Engelpracht2017 | `ηvol = a1 + a2*((π-c1)/c2) + a3*((Tinl-c3)/c4)*((π-c1)/c2) + a4*((Tinl-c3)/c4) + a5*((n-c5)/c6) + a6*((n-c5)/c6)^2` | Generic model | `0 - 120` | `1 - 10`

#### Power volumetric 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.VolumetricEfficiency.PowerVolumetricEfficiency.

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Reference | Formula | Refrigerants | Validity `ncompressor` | Validity `Πpressure`
--- | --- | --- | --- | ---
MendozaMirandaEtAl2016 | `ηvol = a1 * π^b1 * (π^1.5*n^3*Vdis)^b2 * (Mref/M)^b3` | 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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