Description: "Functions for fan characteristics"

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## Buildings.Fluid.HeatExchangers.CoolingTowers.BaseClasses.Characteristics

Functions for fan characteristics

### Information

This package implements performance curves for fans and pumps, and records for parameter that can be used with these performance curves.

See the User's Guide for information about these performance curves.

### Package Content

Name | Description
--- | ---
efficiency | Flow vs. efficiency characteristics for fan or pump
efficiencyParameters | Record for efficiency parameters

## Buildings.Fluid.HeatExchangers.CoolingTowers.BaseClasses.Characteristics.efficiency

Flow vs. efficiency characteristics for fan or pump

### Information

This function computes the fan efficiency for given normalized volume flow rate and performance data. The efficiency is

η = s(rV, d),

where η is the efficiency, rV is the normalized volume flow rate, and d are performance data for fan or pump efficiency.

#### Implementation

The function s(·, ·) is a cubic hermite spline. If the data d define a monotone decreasing sequence, then s(·, d) is a monotone decreasing function.

Extends from Modelica.Icons.Function (Icon for functions).

### Inputs

Type | Name | Default | Description
--- | --- | --- | ---
efficiencyParameters | per |  | Efficiency performance data
Real | r_V |  | Volumetric flow rate divided by nominal flow rate [1]
Real | d[:] |  | Derivatives at support points for spline interpolation

### Outputs

Type | Name | Description
--- | --- | ---
Real | eta | Efficiency [1]

### Modelica definition

function efficiency "Flow vs. efficiency characteristics for fan or pump" extends Modelica.Icons.Function; input Characteristics.efficiencyParameters per "Efficiency performance data"; input Real r_V(unit="1") "Volumetric flow rate divided by nominal flow rate"; input Real d[:] "Derivatives at support points for spline interpolation"; output Real eta(min=0, unit="1") "Efficiency"; protected Integer n = size(per.r_V, 1) "Number of data points"; Integer i "Integer to select data interval"; algorithm if n == 1 then eta := per.eta[1]; else i :=1; for j in 1:n-1 loop if r_V > per.r_V[j] then i := j; end if; end for; // Extrapolate or interpolate the data eta:=Buildings.Utilities.Math.Functions.cubicHermiteLinearExtrapolation( x=r_V, x1=per.r_V[i], x2=per.r_V[i + 1], y1=per.eta[i], y2=per.eta[i + 1], y1d=d[i], y2d=d[i+1]); end if; end efficiency;

## Buildings.Fluid.HeatExchangers.CoolingTowers.BaseClasses.Characteristics.efficiencyParameters

Record for efficiency parameters

### Information

Data record for performance data that describe volume flow rate versus efficiency. The volume flow rate `r_V` must be increasing, i.e., `r_V[i] < r_V[i+1]`. Both vectors, `r_V` and `eta` must have the same size.

Extends from Modelica.Icons.Record (Icon for records).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Real | r_V[:] |  | Volumetric flow rate divided by nominal flow rate at user-selected operating points [1]
Real | eta[size(r_V, 1)] |  | Fan efficiency at these flow rates

### Modelica definition

record efficiencyParameters "Record for efficiency parameters" extends Modelica.Icons.Record; parameter Real r_V[:](each min=0, each unit="1") "Volumetric flow rate divided by nominal flow rate at user-selected operating points"; parameter Real eta[size(r_V,1)]( each min=0, each max=1, each displayUnit="1") "Fan efficiency at these flow rates"; end efficiencyParameters;