Buildings.Fluid.Geothermal.Aquifer.Validation

Validation models for aquifer thermal energy storage

Information

This package contains validation models for the classes in Buildings.Fluid.Geothermal.Aquifer.

Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).

Package Content

Name	Description
NumberWells	Test model for aquifer thermal energy storage with multiple wells
SimulationTest	Test model for aquifer thermal energy storage in comparison with other geothermal simulators

Buildings.Fluid.Geothermal.Aquifer.Validation.NumberWells

Test model for aquifer thermal energy storage with multiple wells

Buildings.Fluid.Geothermal.Aquifer.Validation.NumberWells

Information

Example that verifies the scalability of Buildings.Fluid.Geothermal.Aquifer.MultiWell when multiple wells are used.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Modelica definition

model NumberWells "Test model for aquifer thermal energy storage with multiple wells" extends Modelica.Icons.Example; package Medium = Buildings.Media.Water "Medium model"; model MyWell = MultiWell ( redeclare package Medium = Buildings.Media.Water, nVol=50, h=10, d=4800, length=200, THot_start=303.15, TGroCol=273.15, TGroHot=303.15, aquDat=Buildings.Fluid.Geothermal.Aquifer.Data.Rock(), m_flow_nominal=0.1, dpExt_nominal=0) "Well model"; MyWell aquWel1(d=4800) "ATES with one pair of wells"; MyWell aquWel2( d=4800, nPai=2, m_flow_nominal=0.2) "ATES with two pairs of wells"; Modelica.Blocks.Sources.Constant uPum(k=1) "Pump control signal"; Sources.Boundary_pT bou( redeclare package Medium = Medium, nPorts=2) "Sink"; Modelica.Blocks.Sources.RealExpression temWel1( y=aquWel1.TAquHot[10]) "Temperature output from aquifer model with one pair of wells"; Modelica.Blocks.Sources.RealExpression temWel2( y=aquWel2.TAquHot[10]) "Temperature output from aquifer model with two pairs of wells"; Buildings.Utilities.Diagnostics.CheckEquality cheEqu "Assertion that checks for equality of results"; equation connect(uPum.y, aquWel1.u); connect(aquWel2.u,uPum. y); connect(aquWel2.port_Col, aquWel2.port_Hot); connect(aquWel1.port_Col, aquWel1.port_Hot); connect(bou.ports[1], aquWel1.port_Hot); connect(bou.ports[2], aquWel2.port_Hot); connect(cheEqu.u1, temWel1.y); connect(cheEqu.u2, temWel2.y); end NumberWells;

Buildings.Fluid.Geothermal.Aquifer.Validation.SimulationTest

Test model for aquifer thermal energy storage in comparison with other geothermal simulators

Buildings.Fluid.Geothermal.Aquifer.Validation.SimulationTest

Information

This validation case simulates an idealized operation of an aquifer thermal storage system. Results are compared with simulations from a test suite developed by Mindel et al. (2021). This test suite comprises a set of cases to assess the thermo-hydraulic modelling capabilities of various geothermal simulators.

The comparison was carried out with respect to the test case called TC2 - well-test comparison. The main goal of TC2 is to compare aquifer temperatures under a typical operation of an ATES system consisting of injection, falloff, drawdown, and build-up. The injection phase represents the charging period, while the drawdown phase represents the discharge period. Intermediate phases of falloff and build-up represent periods of storage or inactivity. The overall operational period is one year, and the sequence of the different phases is the following:

Injection: Water is pumped at Q = 0.001 m³ s^-1 and T_inj = 120C for 120 days.
Falloff: Well is shut-in, Q = 0 m³ s^-1 for 60 days.
Drawdown: Water is pumped at Q = -0.001 m³ s^-1 for 120 days.
Build-up phase: Well is shut-in, at Q = 0 m³ s^-1 for 65.25.

The figure below shows the temperature vs. time comparison for a virtual sensor located at r = 1 m and r= 10 m from the well.

References

Julian E. Mindel, Peter Alt-Epping, Antoine Armandine Les Landes, Stijn Beernink, Daniel T. Birdsell, Martin Bloemendal, Virginie Hamm, Simon Lopez, Charles Maragna, Carsten M. Nielsen, Sebastia Olivella, Marc Perreaux, Maarten W. Saaltink, Martin O. Saar, Daniela Van den Heuvel, Ruben Vidal, Thomas Driesner, Benchmark study of simulators for thermo-hydraulic modelling of low enthalpy geothermal processes, Geothermics, Volume 96, 2021, 102130, ISSN 0375-6505, https://doi.org/10.1016/j.geothermics.2021.102130.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Modelica definition

model SimulationTest "Test model for aquifer thermal energy storage in comparison with other geothermal simulators" extends Modelica.Icons.Example; package Medium = Buildings.Media.Water "Medium model"; MultiWell aquWel( redeclare package Medium = Medium, nVol=232, h=200, d=4800, length=40, griFac=1.1, TCol_start=307.15, THot_start=393.15, TGroCol=307.15, TGroHot=393.15, aquDat=Buildings.Fluid.Geothermal.Aquifer.Data.Rock(), m_flow_nominal=1, dpExt_nominal=0) "Aquifer wells"; Sources.Boundary_pT bou( redeclare package Medium = Medium, nPorts=1) "Boundary condition for pressure"; Modelica.Blocks.Sources.CombiTimeTable uPum(table=[0.0,-1; 86400*120,-1; 86400 *120,0; 86400*180,0; 86400*180,1; 86400*300,1; 86400*300,0]) "Pump control signal"; equation connect(aquWel.port_Col, aquWel.port_Hot); connect(bou.ports[1], aquWel.port_Hot); connect(uPum.y[1], aquWel.u); end SimulationTest;

Buildings.Fluid.Geothermal.Aquifer.Validation.NumberWells.MyWell

Well model

Buildings.Fluid.Geothermal.Aquifer.Validation.NumberWells.MyWell

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Height	h	10	Aquifer thickness [m]
Length	d	4800	Distance between wells [m]
Height	length	200	Length of one well, used to compute pressure drop [m]
Real	nPai	1	Number of paired wells
Template	aquDat	Buildings.Fluid.Geothermal.A...	Aquifer thermal properties
Subsurface
Integer	nVol	50	Number of control volumes used in discretization
Radius	rWB	0.1	Wellbore radius [m]
Radius	rMax	d/2	Domain radius [m]
Real	griFac	1.15	Grid factor for spacing
Temperature	TCol_start	283.15	Initial temperature of cold well [K]
Temperature	THot_start	303.15	Initial temperature of warm well [K]
Properties of ground
Temperature	TGroCol	273.15	Undisturbed ground temperature (cold well) [K]
Temperature	TGroHot	303.15	Undisturbed ground temperature (warm well) [K]
Hydraulic circuit
MassFlowRate	m_flow_nominal	0.1	Nominal mass flow rate [kg/s]
PressureDifference	dpAquifer_nominal	m_flow_nominal/nPai*Modelica...	Pressure drop at nominal mass flow rate in the aquifer [Pa]
PressureDifference	dpExt_nominal	0	Pressure drop at nominal mass flow rate in the above-surface system (used to size the head of the well pump) [Pa]

Connectors

Type	Name	Description
replaceable package Medium		Medium in the component
input RealInput	u	Pump control input (-1: extract from hot well, +1: extract from cold well, 0: off) [1]
output RealOutput	PTot	Total power consumed by all circulation pumps in the wells [W]
FluidPort_a	port_Col	Fluid connector
FluidPort_a	port_Hot	Fluid connector

Modelica definition

model MyWell = MultiWell ( redeclare package Medium = Buildings.Media.Water, nVol=50, h=10, d=4800, length=200, THot_start=303.15, TGroCol=273.15, TGroHot=303.15, aquDat=Buildings.Fluid.Geothermal.Aquifer.Data.Rock(), m_flow_nominal=0.1, dpExt_nominal=0) "Well model";