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Experimental and numerical characterisation of the thermo-mechanical
behaviour of quadratic cross section energy pilesIndustrial PhD
Intro dias
Sidefod
Dias 2
Dias med to billeder
Industrial PhD
Experimental and numerical characterisation of the thermo-mechanical
behaviour of quadratic cross section energy piles
Shallow Geothermal Energy
Dias med 5. element, til grafik – fx grafer
GEOTHERMAL EXCHANGE UNIT (HEAT PUMP)
GROUND LOOP (BHE)
HEATING SUPPLY SYSTEM
HEAT INPUT FROM THE SUN TO THE GROUND
HEAT INPUT FROM GEOTHERMAL FLUX
HEATING
COOLING
STORAGE
Use underground potential
Surface
≈10 oC at 100m depth
Dias 4
Concept of Energy Pile
Dias med 5. element, til grafik – fx grafer
Concrete foundation pile that serves as both structural
and geothermal heat exchanger element
Heating and cooling purposes
Energy piles will reduce the need for conventional heating
and cooling and will thereby reduce the carbon footprint of
a new building
Ske
tch
of a
n in
div
idu
al e
ne
rgy p
ile
Dias 5
Interest in Energy Piles
Dias med 5. element, til grafik – fx grafer
Determination of soil thermal properties
Important to know the soil and its thermal properties:
optimize the design of our Ground Source Heat Pump system!
3 thermal properties:
- Thermal conductivity [W/m/K]
- Heat capacity [J/kg/K] or volumetric heat capacity [J/m3/K]
- Thermal diffusivity [m/s]
Ways to determine the thermal properties:
1. Literature values
2. Laboratory measurements
3. In-situ Thermal Response Test (TRT)
Why don’t you
do a TRT in an
Energy Pile?
Dias 6
Thermal Response Test
Dias med 5. element, til grafik – fx grafer
In-situ test to measure 2 main parameters of the vertical BHE system:
1) Thermal Conductivity of the ground (λeff)
2) Borehole Thermal Resistance (Rb)
Purpose: Design tool, correct dimensioning of large installations (> 30 kW) + …
Effective heat exchanger = Low Rb
Save money Save time Quality control Research
Dias 7
Thermal Response Test
Dias med 5. element, til grafik – fx grafer
REMEMBER! Why do we execute a TRT?
1) Thermal Conductivity of the ground (λeff)
2) Borehole Thermal Resistance (Rb)
With these 2 parameters and…
• Demand
• Heat Pump capacity
• Heat carrier fluid properties
• …
Our GSHP system can be dimensioned!
Dias 8
Thermal Response Test
Dias med 5. element, til grafik – fx grafer
A constant heat injection power is imposed
(warm water) into the BHE (closed circuit). As
heat dissipates below ground, the borehole
and the surrounding ground are heated.
Continuous Data Monitoring:
time, fluid inlet and outlet temperatures and
flow.
Duration: at least 48 hours.
T1 > T2
Dissipated heat
ww
w.u
beg
.de
Dias 9
TRT at Rosborg Gymnasium (Vejle)
Dias med 5. element, til grafik – fx grafer
Dias 10
Thermal Response Test (UBeG)
Dias med 5. element, til grafik – fx grafer
17. februar 201610
Heater
Expansion
Vessel
Pressure Valve
Manometer
Temperature
sensors
Circuit
filling hose
Flow in BHE
Flow out BHE
Circulation PumpFlow-meter
ww
w.u
beg
.de
Dias 11
Thermal Response Test
Dias med 5. element, til grafik – fx grafer
BHE [Borehole Resistance Rb]
Transient BHE response
Ground [Soil Thermal Conductivity λ]
Quasi Steady-State response
Measured input and output temperatures over the TRT
Forskningens Døgn 2015
Dias 12
Motivation of the PhD
Dias med 5. element, til grafik – fx grafer
TRT interpretation Used to traditional BHE
Traditional TRT evaluation methods cannot be applied to Energy Piles
Quadratic cross section energy piles have not been deeply investigated
Lack of design guidelines for thermo-active foundations (still uncertainties)
VS
LengthCross Section
Problem! BHE ≠ Energy Pile
100 m (BHE) VS 15 m (Energy Pile)
Ø ≈0.16 m
Dias 13
Description of the PhD
Dias med 5. element, til grafik – fx grafer
Industrial PhD
Better knowledge of the energy pile,
more optimized design
Valuable information for the company
Objectives:
1. Thermal Performance
2. Structural Behaviour
3. Operational Demonstration
Methodology:
Applied research: data + models
Dias 14
Dias med 5. element, til grafik – fx grafer
14
Maria Alberdi
Why is it important to have data?
DATA ANALYSIS MODELSKNOW
REALITY
Dias 15
Case Study
Dias med 5. element, til grafik – fx grafer
Rosborg Gymnasium, Vejle
Extensionof the building. 200 energy piles (2011)
200 kW heat pump
New planned building 220 energy piles
(summer 2015)
165 kW heat pump
Forskningens Døgn 2015
Dias 16
Description of the PhD: Partners
Dias med 5. element, til grafik – fx grafer
POTENTIAL PARTNERS:
International Universities
COST Action
Dias 17
Tak
Dias med 5. element, til grafik – fx grafer
?
More information about energy piles:
www.centrumpaele.dk
Maria Alberdi-Pagola: [email protected]
