AixLib.Fluid.Movers.Compressors.UsersGuide.Approaches.MechanicEfficiency

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

Mechanic Efficiencies

## Information

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

#### 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 engine 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.EngineEfficiency.PolynomialEngineEfficiency.

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Reference | Formula | Refrigerants | Validity `ncompressor` | Validity `Πpressure`
--- | --- | --- | --- | ---
JahningEtAl2000 | `ηeng = a1 + a2*exp(pInl)^b2` | Generic model | `Generic model` | `Generic model`
DurprezEtAl2007 | `ηeng = a1 + a2*π + a3*π^2 + a4*π^3 + a5*π^4 + a6*π^5 + a7*π^6` | Generic model | `Generic model` | `Generic model`
KinarbEtAl2010 | `ηeng = a1 + a2*π + a3*π^2` | Generic model | `Generic model` | `Generic model`
Engelpracht2017 | `ηeng = a1 + a2*π + a3*π^2 + a4*n*π + a5*n^2 + a6*π^2*n + a7*π*n^2 + a8*n^3 + a9*π^2n^2 + a10*π*π^3 + a11*n^4` | Generic model | `0 - 120` | `1 - 10`

#### Power engine 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.EngineEfficiency.PowerEngineEfficiency.

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Reference | Formula | Refrigerants | Validity `ncompressor` | Validity `Πpressure`
--- | --- | --- | --- | ---
MendozaMirandaEtAl2016 | `ηeng = a1 * π^b1 * (nref/n)^b2 * (1/((TInl+TOutIse)/2-TOut))^b3 * (Mref/M)^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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