Buildings.Fluid.HeatExchangers.CoolingTowers.BaseClasses.Characteristics

Functions for fan characteristics

Information

This package implements the performance curve for the fans, and a record for performance data that can be used with the performance curve.

Package Content

Name	Description
normalizedPower	Normalized flow vs. normalized power characteristics for fan
fan	Record for fan power consumption
Validation	Collection of models that validate the cooling tower models

Buildings.Fluid.HeatExchangers.CoolingTowers.BaseClasses.Characteristics.normalizedPower

Normalized flow vs. normalized power characteristics for fan

Information

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

r_P = s(r_V, d),

where r_P; is the normalized fan power consumption, r_V 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	Description
fan	per	Fan relative power consumption
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
Efficiency	r_P	Normalized power consumption [1]

Modelica definition

function normalizedPower "Normalized flow vs. normalized power characteristics for fan" extends Modelica.Icons.Function; input Characteristics.fan per "Fan relative power consumption"; 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 Modelica.Units.SI.Efficiency r_P(max=1) "Normalized power consumption"; protected Integer n = size(per.r_V, 1) "Number of data points"; Integer i "Integer to select data interval"; algorithm if n == 1 then r_P := per.r_V[1]; else // Compute index for power consumption 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 r_P:=Buildings.Utilities.Math.Functions.cubicHermiteLinearExtrapolation( x=r_V, x1=per.r_V[i], x2=per.r_V[i + 1], y1=per.r_P[i], y2=per.r_P[i + 1], y1d=d[i], y2d=d[i+1]); end if; end normalizedPower;

Buildings.Fluid.HeatExchangers.CoolingTowers.BaseClasses.Characteristics.fan

Record for fan power consumption

Information

Data record for performance data that describe normalized volume flow rate versus normalized fan power consumption. The normalized volume flow rate r_V must be increasing, i.e., r_V[i] < r_V[i+1]. Both vectors, r_V and r_P 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	r_P[size(r_V, 1)]		Fan relative power consumption at these flow rates such that r_P = 1 for r_V=1

Modelica definition

record fan "Record for fan power consumption" 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 r_P[size(r_V,1)](each max=1) "Fan relative power consumption at these flow rates such that r_P = 1 for r_V=1"; end fan;