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Cooling tower first model #472
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So now the heat exchange is between the water source and water sink, so the component hot_side_cooling
should be replace by an IsoPHFlowModel
(at the moment it is an IsoPFlowModel
)
@@ -107,7 +107,7 @@ equation | |||
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// Observable for Calibration | |||
WaterOutletTemp_sensor.T_degC = WaterOutletTemp; | |||
AirOutletTemp_sensor.T_degC = AirOutletTemp; | |||
AirOutletTemp_sensor.T_degC = AirOutletTemp-10*time; |
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Be careful to not forget *time
in your model, it should be used only for testing
@@ -32,7 +32,7 @@ model CoolingTower_reverse | |||
output Real Q_cold(start=52552.133) "m3/s"; | |||
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output Real airOutletPress(start=1) "bar"; | |||
output Real AirOutletTemp(start=35) "deg_C"; | |||
input Real AirOutletTemp(start=35) "deg_C"; //output |
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With the correction on the component (isoPH instead of isoP), you won't have anymore to impose this temperature
Water_outlet.T_out = Water_inlet.T_in; | ||
Water_outlet.Q_out = Water_inlet.Q_in - Q_makeup; | ||
//Water_outlet.T_out = Water_inlet.T_in; | ||
Water_outlet.Q_out = Q_hot - Q_makeup; |
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Q_out it negative (flow going out a componenet is negative by convention, so here it should be :
Water_outlet.Q_out = - (Q_hot - Q_makeup);
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I think it could be a could idea to create a new variable Q_hot_out
and renaming Q_hot
by Q_hot_in
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Good job, with a lower air temperature the Hd should be positive. But we should keep this in mind because a CT is working even if the air is warmer than the water. Maybe that's a limit of our hypothesis.
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Good job, I made some small test and the results looks good.
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This file can be deleted now, we keep only the model with supersaturated air
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Rename the file CoolingTowerPoppe
import MetroscopeModelingLibrary.Utilities.Media.WaterSteamMedium; | ||
import MetroscopeModelingLibrary.Utilities.Media.MoistAirMedium.specificEnthalpy; | ||
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//Unsaturated Air |
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It could be useful to put in comment where does the equations come from
Inputs.InputReal hd; | ||
Inputs.InputArea Afr; | ||
Inputs.InputReal Lfi; | ||
Inputs.InputFrictionCoefficient Cf; |
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Put in comment the full name of the parameters
// Poppe Inputs | ||
Units.Temperature deltaTw; | ||
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parameter Integer N_step = 10; |
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This parameter should be at the top of the model and have a description
Lef[1] = 0.9077990913 * (((MoistAir.xsaturation_pT(Pin[1], T_cold_in)+0.622)/(w[1]+0.622))-1) / log((MoistAir.xsaturation_pT(Pin[1], T_cold_in)+0.622)/(w[1]+0.622)); | ||
cp[1] = WaterSteamMedium.specificHeatCapacityCp(water_inlet_flow.state_in); | ||
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// Drift Equation |
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This equation is correct only for natural draft cooling tower. I think we should also add the equation that describe the fans behaviour with an if condition to selected the configuration. Something like:
if configuration = "natural draft" then
...
else
...
This has to be done also for the Merkel model.
Real Lef[N_step]; | ||
Units.MassFlowRate Qw[N_step]; | ||
Units.MassFlowRate Qa[N_step]; | ||
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It would be interesting to add the estimation of the rejected heat in MW
y:= cp / ((MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i + (Lef-1) * (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i - (MoistAir.xsaturation_pT(Pin, Tw) - MoistAir.xsaturation_pT(Pin, Ta)) * MoistAir.h_pTX(Pin, Tw, {1})) + (w - MoistAir.xsaturation_pT(Pin, Ta)) * cp * Tw) + (w - MoistAir.xsaturation_pT(Pin, Tw)) * cp * Tw); | ||
end m; | ||
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Units.Velocity V_inlet; //Wind velocity entering cooling tower |
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Units.Velocity V_inlet; //Wind velocity entering cooling tower | |
Units.Velocity V_inlet; //Air velocity at the bottom of the cooling tower |
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I made a few comments to improve the CT components (mainly to make them clearer).
Also, don't forget to change the connector for the air side
@@ -0,0 +1,314 @@ | |||
within MetroscopeModelingLibrary.MultiFluid.HeatExchangers; | |||
model CoolingTowerPoppe |
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Add a comment with the reference of the article we used
parameter Integer N_step = 10; //Parameter specifies the number of sections for which the Cooling Tower thermodynamic properties are divided into in the loop. | ||
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//Unsaturated Air - Equations from Poppe Method for Cooling Tower Analysis | ||
function f |
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Give a description for this function with the reference of the equation, see this example:
function quadrature "Integrate function y=integrand(x) from x1 to x2"
input Real x1;
input Real x2;
input Integrand integrand; // Integrand is a partial function, see below
// With default: input Integrand integrand := Modelica.Math.sin;
output Real integral;
algorithm
integral :=(x2-x1)*(integrand(x1) + integrand(x2))/2;
end quadrature;
y:= (cp * (Qw / Qa) * (MoistAir.xsaturation_pT(Pin, Tw) - w)) / (((MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)})) - i + (Lef-1) * ((MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i - (MoistAir.xsaturation_pT(Pin, Tw) - w) * MoistAir.h_pTX(Pin, Tw, {1}))) - (MoistAir.xsaturation_pT(Pin, Tw) - w) * cp * Tw)); | ||
end f; | ||
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function g |
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Add a descriptions of the function
y:= ((Qw * cp) / Qa) * (1 + (((MoistAir.xsaturation_pT(Pin, Tw) - w) * (cp * Tw)) / ((MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i + ((Lef-1) * (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i - (MoistAir.xsaturation_pT(Pin, Tw) - w) * MoistAir.h_pTX(Pin, Tw, {1}))) - (MoistAir.xsaturation_pT(Pin, Tw) - w) * cp * Tw)))); | ||
end g; | ||
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function h |
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Add a description of the function
import MetroscopeModelingLibrary.Utilities.Media.WaterSteamMedium; | ||
import MetroscopeModelingLibrary.Utilities.Media.MoistAirMedium.specificEnthalpy; | ||
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Units.Velocity V_inlet; //Wind velocity entering cooling tower |
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Units.Velocity V_inlet; //Wind velocity entering cooling tower | |
Units.Velocity V_inlet; //Air velocity at the bottom of the cooling tower |
Inputs.InputReal efan; //Fan effiency | ||
Units.Power W_fan; //Fan power | ||
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parameter String configuration = "natural draft"; |
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parameter String configuration = "natural draft"; | |
parameter String configuration = "natural"; |
//Supersaturated Air - Equations from Poppe Method for Cooling Tower Analysis | ||
function j | ||
input Real Tw; | ||
input Real Ta; | ||
input Real w; | ||
input Real i; | ||
input Real cp; | ||
input Real Qw; | ||
input Real Qa; | ||
input Real Pin; | ||
input Real Lef; | ||
output Real y; | ||
algorithm | ||
y:= (cp * (Qw / Qa) * (MoistAir.xsaturation_pT(Pin, Tw) - MoistAir.xsaturation_pT(Pin, Ta))) / (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i + (Lef-1) * (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i - (MoistAir.xsaturation_pT(Pin, Tw) - MoistAir.xsaturation_pT(Pin, Ta)) * (MoistAir.h_pTX(Pin, Tw, {1})) + (w - MoistAir.xsaturation_pT(Pin, Ta)) * cp * Tw) + (w - MoistAir.xsaturation_pT(Pin, Tw)) * cp * Tw); | ||
end j; |
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//Supersaturated Air - Equations from Poppe Method for Cooling Tower Analysis | |
function j | |
input Real Tw; | |
input Real Ta; | |
input Real w; | |
input Real i; | |
input Real cp; | |
input Real Qw; | |
input Real Qa; | |
input Real Pin; | |
input Real Lef; | |
output Real y; | |
algorithm | |
y:= (cp * (Qw / Qa) * (MoistAir.xsaturation_pT(Pin, Tw) - MoistAir.xsaturation_pT(Pin, Ta))) / (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i + (Lef-1) * (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i - (MoistAir.xsaturation_pT(Pin, Tw) - MoistAir.xsaturation_pT(Pin, Ta)) * (MoistAir.h_pTX(Pin, Tw, {1})) + (w - MoistAir.xsaturation_pT(Pin, Ta)) * cp * Tw) + (w - MoistAir.xsaturation_pT(Pin, Tw)) * cp * Tw); | |
end j; | |
function j "Supersaturated Air - Equations from Poppe Method for Cooling Tower Analysis" | |
input Real Tw; | |
input Real Ta; | |
input Real w; | |
input Real i; | |
input Real cp; | |
input Real Qw; | |
input Real Qa; | |
input Real Pin; | |
input Real Lef; | |
output Real y; | |
algorithm | |
y:= (cp * (Qw / Qa) * (MoistAir.xsaturation_pT(Pin, Tw) - MoistAir.xsaturation_pT(Pin, Ta))) / (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i + (Lef-1) * (MoistAir.h_pTX(Pin, Tw, {MoistAir.xsaturation_pT(Pin, Tw)}) - i - (MoistAir.xsaturation_pT(Pin, Tw) - MoistAir.xsaturation_pT(Pin, Ta)) * (MoistAir.h_pTX(Pin, Tw, {1})) + (w - MoistAir.xsaturation_pT(Pin, Ta)) * cp * Tw) + (w - MoistAir.xsaturation_pT(Pin, Tw)) * cp * Tw); | |
end j; |
Units.Temperature T_hot_in; | ||
Units.Temperature T_hot_out; | ||
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// Poppe Inputs |
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// Poppe Inputs |
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for n in 1:N_step-1 loop | ||
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if w[n] < w_sat[n] then |
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Add a few comments to explain the loop and the if condition
rho_air_inlet = air_inlet_flow.rho_in; | ||
rho_air_outlet = air_outlet_flow.rho_out; | ||
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//if configuration = "natural draft" then |
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You can take the same equation of the Merkel model
Goal
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package.mo
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