Experimental and numerical characterisation of the thermo-mechanical
behaviour of quadratic cross section energy piles
Industrial PhD
Dias 2
Industrial PhD
Experimental and numerical characterisation of the thermo-mechanical
behaviour of quadratic cross section energy piles
Sidefod
Shallow Geothermal Energy
HEATING
SUPPLY SYSTEM
HEAT INPUT
FROM THE SUN
TO THE
GROUND
Use underground
potential
GEOTHERMAL
EXCHANGE
UNIT (HEAT
PUMP)
GROUND LOOP
(BHE)
HEATING
COOLING
STORAGE
Surface
HEAT INPUT FROM
GEOTHERMAL FLUX
≈10 oC at 100m depth
Dias 4
Concept of Energy Pile
Concrete foundation pile that serves as both structural
and geothermal heat exchanger element
Heating and cooling purposes
Sketch of an individual energy pile
Energy piles will reduce the need for conventional heating
and cooling and will thereby reduce the carbon footprint of
a new building
Dias 5
Interest in Energy Piles
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/m 3/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
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) + …
Save money
Save time
Quality control
Effective heat exchanger = Low Rb
Research
Dias 7
Thermal Response Test
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
Continuous Data Monitoring:
time, fluid inlet and outlet temperatures and
flow.
Duration: at least 48 hours.
T1 > T2
Dissipated heat
www.ubeg.de
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.
Dias 9
TRT at Rosborg Gymnasium (Vejle)
Dias 10
Thermal Response Test (UBeG)
Heater
Pressure Valve
Manometer
Circuit
filling hose
Circulation Pump
Temperature
sensors
17. februar 2016
10
Flow in BHE
Flow out BHE
www.ubeg.de
Flow-meter
Expansion
Vessel
Dias 11
Thermal Response Test
Ground [Soil Thermal Conductivity λ]
Quasi Steady-State response
BHE [Borehole Resistance Rb]
Transient BHE response
Measured input and output temperatures over the TRT
Dias 12
Motivation of the PhD
TRT interpretation  Used to traditional BHE
BHE ≠ Energy Pile
Problem!
VS
100 m (BHE) VS 15 m (Energy Pile)
Ø ≈0.16 m
Cross Section
Length
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)
Forskningens Døgn 2015
Dias 13
Description of the PhD
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
Why is it important to have data?
DATA
ANALYSIS
Maria Alberdi
MODELS
KNOW
REALITY
14
Dias 15
Case Study
Rosborg Gymnasium, Vejle
New planned building
220 energy piles
(summer 2015)
165 kW heat pump
Extension of the building.
200 energy piles (2011)
200 kW heat pump
Dias 16
Description of the PhD: Partners
POTENTIAL
PARTNERS:
International Universities
COST Action
Forskningens Døgn 2015
Dias 17
Tak
?
More information about energy piles:
www.centrumpaele.dk
Maria Alberdi-Pagola: [email protected]