Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Please note that all times are shown in the time zone of the conference. The current conference time is: 13th Aug 2022, 19:50:54 CEST

 
 
Session Overview
Session
Session T2.1: Practice and industry related case studies
Time:
Thursday, 02/Sept/2021:
10:30 - 12:00

Session Chair: Eline Himpe, Ghent University
Session Chair: Iago Cupeiro, KU Leuven
Location: Cityhall (Belfry) - Room 1


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Presentations
10:30 - 10:48
ID: 30540 / Session T2.1: 1
Topics: Heating, Ventilation and Air Conditioning (HVAC)
Keywords: building energy simulation, TABS, simplified RC model, design

Developing a simplified methodology for simulating energy performance of buildings with thermally activated building systems

Mohsen Sharifi, Josué Borrajo Bastero, Rana Mahmoud, Eline Himpe, Jelle Laverge

Ghent university, Belgium

Aim and Approach

(max 200 words)

Detailed building models allow the HVAC designers to find optimal solutions. However, more complexity in modelling will also result in more efforts for the designers in the component sizing procedure specially when the optimal design of the system is highly depended on the control system. In Thermally Activated Building Systems (TABS), which are embedded pipes in the concrete of the building structure, the role of control is pivotal and thus the control has to be simulated during the design. Therefore, the building model and optimal control has to be coupled to an optimisation algorithm for optimal component sizing. This makes a computationally heavy pre-design procedure. This paper addresses the need for a for a simplified methodology for modelling building with TABS. We calculated the dynamic hourly heating and cooling loads of three case studies with white-box method and used them in simplified resistor-capacitor (RC) model developed by the grey-box approach and the parameters of RC model were estimated by inverse modelling approach. The methodology was applied on three different case studies and the results imply that the developed model by proposed methodology can be confidently coupled to an optimal control to be used for sizing HVAC components.

Scientific Innovation and Relevance

(max 200 words)

1-An automated algorithm for modelling building with TABS

2-Taking the advantage of white-box modelling to have high accuracy

3- Dynamic thermal behavior of the building can be incorporated to the design procedure with a simple model

Preliminary Results and Conclusions

(max 200 words)

Using built-in Modelica libraries and prepared code, the building demand is calculated accurately and easily. Then, a simplified model is derived by the proposed methodology and optimal sizing of HVAC components can be achieved in the early stage of design without expensive mathematical calculations. The first simulation results show that the simplified model can predict the dynamic thermal behaviour of the building accurately and the designer can be confident about the sizing of components when suing the proposed methodology.

Main References

(max 200 words)

1- W. Boydens, D. Costola, A. Dentel, T. Dippel, L. Ferkl, A. Görtgens, L. Helsen, J. Hoogmartens, B.W. Olesen, W. Parijs, M. Sourbron, C. Verhelst, J. Verheyen, C. Wagner, REHVA Guidebook No. 20: Improved system design and control of GEOTABS buildings: Design and operation of GEOTABS systems, REHVA, Brussels, 2013. www.rehva.eu.

2- Sharifi, M., Mahmoud, R., Himpe, E., & Laverge, J. (n.d.). Interaction of GEOTABS and secondary heating and cooling systems in hybridGEOTABS buildings : towards a sizing methodology.

3- Sourbron, M. (2012). Dynamic thermal behaviour of buildings with concrete core activation. PhD thesis

4-Jorissen, F. (2018). Toolchain for Optimal Control and Design of Energy Systems in Buildings. (April). Retrieved from https://limo.libis.be/primo-explore/fulldisplay?docid=LIRIAS1652305&context=L&vid=Lirias&search_scope=Lirias&tab=default_tab&lang=en_US

30540_Sharifi_Mohsen.pdf


10:48 - 11:06
ID: 30377 / Session T2.1: 2
Keywords: Ground Source Heat Pumps, Borehole heat exchanger, Heat pump, Heat transfer

Analysis of the thermal performance of a ground water storage cell with helical shaped pipe for ground source heat pumps

Marco Marigo1, Enrico Prataviera1, Sara Bordignon1, Michele Bottarelli2, Angelo Zarrella1

1Department of Industrial Engineering, University of Padova, Italy; 2Architecture Department, University of Ferrara, Italy

Aim and Approach

(max 200 words)

Ground Source Heat Pump (GSHP) systems are promising technologies that can reduce fossil fuel consumption and CO2 emission due to the air-conditioning in buildings. The advantages of this technology compared to air-source heat pumps are well-known. However, the installation of vertical ground heat exchanger is expensive, consequently alternative solutions are necessary.

In this work, a particular vertical ground heat exchanger for residential buildings is studied. It consists of a helical shaped pipe installed in a water tank (cell) buried into the ground. The water of the tank can be groundwater or greywater from the dwelling. The bottom of the cell is installed at about 3 m under the ground surface. Different cells with helical shaped pipe can be coupled in parallel to the heat pump that provides heating and cooling for the building.

The new system was installed in a residential building in Treviso (Italy) and its temperatures were monitored on the long-term. Numerical simulations in transient conditions via a commercial finite element software were carried out to analyse the thermal behaviour of the cell. The long-term performance of the system was also simulated through a numerical model named CaRM (Capacity Resistance Model), which was modified to simulate this system.

Scientific Innovation and Relevance

(max 200 words)

Ground heat exchangers for GSHP can be vertically or horizontally oriented. For vertical ground heat exchangers, deep vertical bores need to be drilled increasing the initial cost of the installation. In addition, deep bores (usually 100 m long) are not feasible in some locations due to geological and legal constraints. Horizontal ground heat exchangers are installed at shallow depths (usually less than 2 m) requiring significantly more surface. Moreover, decreasing the depth of installation, they are more affected by weather variations.

In the presented heat exchanger, the higher thermal capacitance of the water in the tank is exploited in order to store energy, limit the peak loads and establish suitable control strategies. The heat transfer between ground and tank is continuous, and it is not related to the operation of the system. The lower depth allows the installation without the necessity of legal permissions and the maintenance is easier. The initial cost for the installation is lower than a drilling for a common vertical borehole heat exchanger.

Preliminary Results and Conclusions

(max 200 words)

A model in a finite element software was built to analyse the thermal behaviour of the system in the short term. In particular, the transient response to a heat load profile of the whole system was investigated analysing the heat exchanged between cell and ground, in both heating and cooling mode. A sensitivity analysis on the main parameters (e.g. geometry and material of the tank, pitch of the helical shaped pipe, installation depth, ground thermal properties) was carried out studying the effect on the thermal performance of the system. Then, a capacitance-resistance model was also developed for long-term simulations.

Simulation results are in good agreement with field measurements. They show the relationship between the temperature change and the volume of water in the cell. In addition, the new system is also compared with a common double U-tube configuration in terms of thermal performance on the long-term and from the economic point of view. The economic analysis points out the lower cost of the new solution.

Main References

(max 200 words)

Warner J, Liu X, Shi L, Qu M, Zhang M. A novel shallow bore ground heat exchanger for ground source heat pump applications - Model development and validation. Applied Thermal Engineering 2020; 164:114460.

Zhang M, Liu X, Biswas K, Warner J. A 3D numerical investigation of a novel shallow bore ground heat exchanger integrated with phase change material. Applied Thermal Engineering 2019; 162:114297.

Bonamente E, Aquino A, Cotana F. A PCM thermal storage for ground-source heat pumps: simulating the system performance via CFD approach. Energy Procedia 2016; 101:1079-1086.

Lund JW. Geothermal heat pumps - an overview, Geo-Heat Centre Quarterly Bullettin 2001; 22:1–8.

De Carli M, Tonon M, Zarrella A, Zecchin R. A computational capacity resistance model (CaRM) for vertical ground coupled heat exchangers. Renewable Energy 2010; 35:1537-1550

Zarrella A, De Carli M. Heat transfer analysis of short helical borehole heat exchangers. Applied Energy 2013; 102:1477-1491

30377_Marigo_Marco.pdf


11:06 - 11:24
ID: 30717 / Session T2.1: 3
Keywords: Geothermal energy storage, BTES, Heat pump, Hydronics, Control strategies

Borehole thermal energy storage integration: a case study

Jonas Cleiren1, Freek Van Riet2, Kristof Smits1, Wolf Nys1, Roel Vandenbulcke1, Ivan Verhaert3

1Hysopt NV, Antwerp, Belgium; 2Noven NV, Ghent, Belgium; 3EMIB research group, University of Antwerp, Antwerp, Belgium

Aim and Approach

(max 200 words)

In the past decades, a large number of geothermal energy storage systems like Borehole Thermal Energy Storage (BTES) and Aquifer Thermal Energy Storage (ATES) have been widely applied. However, these systems are rather complex to design and prone to design errors, often resulting in suboptimal systems mainly on a hydraulic and control related point of view. In order to obtain a well-functioning system despite the complexity, a case study is conducted to address various optimisation possibilities.

To optimise a BTES system, a case study is conducted using the simulation software Hysopt because it takes both the thermal, as well as the hydraulic and control behaviour into account. In the case study, the initial design of a BTES system is optimised by simulating variants with different thermal, hydraulic and control design choices and comparing the resulting performances with each other. The analysis takes into account different KPIs like the energy consumption/cost, CO2 emission and investment cost.

Scientific Innovation and Relevance

(max 200 words)

Geothermal energy storage systems are called complex because of the combination of multiple types of production units, the possible desired thermal balance of the ground, the different operating conditions and the control strategy. Because of the complexity, extensive professional knowledge is required to design and correctly simulate geothermal energy storage systems. Even when doing so, there will always remain opportunities for improvement.

The conducted case study starts with the optimisation of the distribution network with the end-units to decrease the return and/or supply temperature. Afterwards the hydraulic configuration and control strategy of the energy centre is optimised to increase the contribution of the heat pump, which results in reduced energy consumption and CO2 emissions. The remaining excess heat and/or cold is stored in the BTES. Depending on the difference between extracted and injected heat, the ground can be thermally imbalanced. To address this imbalance, a few alternatives are proposed to improve the thermal balance. In addition, optimisations to keep the investment cost as low as possible are also proposed.

Preliminary Results and Conclusions

(max 200 words)

The conducted case study, including simulation of thermal, hydraulic and control behaviour, resulted in different design options. Depending on the priority of the KPIs, the most suitable design can be chosen.

The different design choices are mostly focused on hydraulic configurations and control strategies, mainly because these aspects are often neglected. In the case study, the energy consumption can be reduced by 40%, the energy cost by 30% and the CO2 emission also by 30%. Furthermore, some design choices lowered the investment cost and improved the thermal balance of the soil.

From the analysis of the simulation results, it can also be concluded that the performance of the system with geothermal energy storage is very sensitive to small adjustments in the hydraulics and controls. Therefore, it is recommended to choose a more robust design, for instance one with relatively simplistic controls, to reduce the error sensitivity.

Main References

(max 200 words)

R. Vandenbulcke, “Hydronic Simulation and Optimisation”, University of Antwerp, 2013.

F. Van Riet, “Hydronic design of hybrid thermal production systems in buildings”, University of Antwerp, 2019.

F. Van Riet, R. Vandenbulcke, J. Cleiren, and I. Verhaert, “Hydronic Optimisation Of Hybrid Heating Systems: A Methodology Based On Base Circuits”, IBPSA Building Simulation 2019.

F. Van Riet, H. El Khaoui, F. Hulsbosch, G. Steenackers, and I. Verhaert, “Exploring the novel software Hysopt: a comparison of hydronic heat distribution systems of an apartment building”, 12th REHVA World Congress CLIMA 2016.

J. Cleiren, “Hydronic design of heat- and cold production systems with geothermal seasonal energy storage”, University of Antwerp, 2018.

X. Q. Zhai, M. Qu, X. Yu, Y. Yang, and R. Z. Wang, “A review for the applications of integrated approaches of ground-coupled heat pump systems”, Renew. Sustain. Energy, vol. 15, no. 6, pp. 3133-3140, 2011.

L. Gao, J. Zhao, Q. An, J. Wang, and X. Liu, “A review on system performance studies of aquifer thermal energy storage”, Energy Procedia, vol. 142, pp. 3537-3545, 2017.

M. Bloemendal, T. Olsthoorn, and F. Boons, “How to achieve optimal and sustainable use of the subsurface for Aquifer Thermal Energy Storage”, Energy Policy, vol. 66, pp. 104-114, 2014.

30717_Cleiren_Jonas.pdf


11:24 - 11:42
ID: 31150 / Session T2.1: 4
Topics: Heating, Ventilation and Air Conditioning (HVAC), Building physics, Developments in simulation
Keywords: hybridGEOTABS, design moment analysis, correlation analysis, simulated database, predesign

Towards a new simulation based hybridGEOTABS design methodology!

Alexander Jean Lucienne Berquin

Boydens Engineering, Belgium

Aim and Approach

(max 200 words)

Providing an easy-to-use method to determine the optimal system powers of hybridGEOTABS in a predesign stage. The new method is based on a design moment analysis and correlation analysis of a simulated database.

Scientific Innovation and Relevance

(max 200 words)

It could be possible to size the different components of hybridGEOTABS in a predesign stage based on correlations between peak demands and optimal system powers.

Preliminary Results and Conclusions

(max 200 words)

It was shown that it is difficult to define specific design conditions to size the hybridGEOTABS components. However, main circumstances could be distinguished for which the system powers are peaking.

Furthermore, It is clear that high correlations exist between peak demands and the optimal system powers in heating and cooling mode. This was also investigated for different climates.

Main References

(max 200 words)

Berquin, A. (2020). Towards a new hybridGEOTABS design methodology! Universiteit Gent.

Franziska Bockelmann, Stefan Plesser, & Hanna Soldaty. (2017). REHVA Guidebook No. 20—Advanced System Design and Operation of GEOTABS Buildings. REHVA.

Mahmoud, R., Himpe, E., Delghust, M., & Laverge, J. (2019). D2.2 A set of parametric geometries for the (sub)typologies studied. UGent.

Sharifi, M., Himpe, E., & Laverge, J. (2019). D2.1 An automated baseload search algorithm for GEOTABS sizing. Universiteit Gent.

31150_Berquin_Alexander Jean Lucienne.pdf


 
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