State of the Art, Perspective and Obstacles of GroundSource Heat Pump Technology in the European Building Sector: A Review
Abstract
:1. Introduction
2. Perspectives and Barriers
3. State of the Art and Technological Developments
3.1. Theoretical Background
3.2. GHE Components’ Materials
3.2.1. Borehole Heat Exchanger Configuration
3.2.2. Pipe Materials
3.2.3. Grout Materials
3.3. Working Fluids
3.3.1. Refrigerant Fluids
3.3.2. Fluid Flowing in the GHEs
3.4. Design and Control Optimization
4. Conclusions
 (i)
 As far as pipe materials are concerned, an optimal value of 1.5–2 W/(m·K) has been defined for thermal conductivity of pipes in GHEs; for this purpose thermally enhanced HDPE is expected to remain the dominant technology, thanks to the possibility to combine the good mechanical properties of conventional HDPE with the high thermal conductivity of additives, especially graphite and aluminum wires. Newer solutions, such as the use of nanomaterials and heat pipe BHEs still require further improvements, although they have demonstrated interesting potential.
 (ii)
 A new benchmark of 2.5–3.3 W/(m·K) has been defined for thermal conductivity of grout materials, which has been proven to be proportional to GHE effectiveness and is inversely related to the length of the GHE and its cost. To reach this optimal value, graphite thermally enhanced grouts remain the best option, both in terms of knowhow and numerical results, achieving thermal conductivities up to 5 W/(m·K) and a reduction of 33% for the required BHE and of 30% for the overall GHE cost. Between new proposals, CLSMs and PCMs have shown good potential, the latter able to reduce thermal interference between pipes, which severely affects conventional thermally spiked grouts. However, the low thermal conductivity of PCMs has necessitated the introduction of thermally enhanced PCMs, whose performances, in terms of thermal conductivity, are still not comparable to those of CLSMs and conventional spiked grouts.
 (iii)
 Micro Phase Change Materials slurries (MPCMS) represent the best substitute to conventional heat transfer fluids at present, providing an increase in the COP and in the heat loadtopumping power ratio compared to water up to 5% and 34% respectively, thanks to the higher heat capacity of PCMs. On the other hand, at the moment, nanofluids are still a noncompetitive technology, due to their high cost, which corresponds to up 12% of total cost of the BHE, and their slight increase in the energy efficiency of GHEs, which does not exceed 5%.
 (iv)
 Finally, great attention has to be paid to proper design and proper control of the GSHP plant, in order to guarantee low operational costs and limit investment cost. Although rulesofthumb and chart approaches are supposed to remain the dominant optimal design methods in the next future, mathematical modelbased methods have a higher chance of solving the optimal designing issue. Moreover, from the control side, the modelbased approach appears to be the preferable one, guaranteeing significant cost savings. In particular, the use of adaptive models such as MPCs have shown great potential for GSHP applications, thanks to the possibility to adapt control operations and predict future scenarios, providing a reduction of operating cost up to 8%. However, to be properly evaluated, optimal design and control methods should be compared with other procedures on the basis of common benchmarks; this point, which remains nowadays mainly unexplored, and the reduction of computational effort and model complexity, should be the focus of research in the future.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Conflicts of Interest
References
 StatisticsEurostat (Europa.Eu). Available online: https://ec.europa.eu/info/news/focusenergyefficiencybuildings2020lut17_en#:~:text=Collectively%2C%20buildings%20in%20the%20EU,%2C%20usage%2C%20renovation%20and%20demolition (accessed on 3 March 2022).
 New Energy Technologies, Innovation and Clean Coal. “Mapping and Analyses of the Current and Future (2020–2030) Heating/Cooling Fuel Deployment (Fossil/Renewables).” Final Report; 2016. Available online: https://ec.europa.eu/energy/sites/default/files/documents/mappinghcexcecutivesummary.pdf (accessed on 3 March 2022).
 TsemekidiTzeiranaki, S.; Labanca, N.; Cuniberti, B.; Toleikyte, A.; Zangheri, P.; Bertoldi, P. Analysis of the Annual Reports 2018 under the Energy Efficiency Directive–Summary Report 2019; European Union: Brussel, Belgium, 2016. [Google Scholar] [CrossRef]
 Directive 2018/844/EU of 30 May 2018 Amending Directive 2010/31/EU on the Energy Performance of Buildings and Directive 2012/27/EU on Energy Efficiency. Available online: https://eurlex.europa.eu/eli/dir/2018/844/oj (accessed on 3 March 2022).
 Directive 2018/2002/EU of 11 December 2018 Amending Directive 2012/27/EU on Energy Efficiency. Available online: https://eurlex.europa.eu/eli/dir/2018/2002/oj (accessed on 3 March 2022).
 RENEWABLES 2021 GLOBAL STATUS REPORT (Ren21.Net). Available online: https://www.ren21.net/reports/globalstatusreport/ (accessed on 3 March 2022).
 EUROBSERVER, Heat Pump Barometer 2020. (Report). Available online: https://www.eurobserver.org/heatpumpsbarometer2020/ (accessed on 3 March 2022).
 Pieve, M.; Trinchieri, R. The HeatPump Market in Italy: An inDepth Economic Study about the Reasons for a Still Unexpressed Potential. Clean Energy 2019, 3, 126–143. [Google Scholar] [CrossRef] [Green Version]
 GEO4CIVHIC. Available online: https://Geo4civhic.Eu (accessed on 21 October 2021).
 Honoré, A. Decabonisation of Heat in Europe: Implications for Natural Gas Demand. Oxf. Inst. Energy Stud. 2018, 130, 1–64. [Google Scholar]
 Abbasi, M.; Abdullah, B.; Ahmad, M.W.; Rostami, A.; Cullen, J. Heat Transition in the European Building Sector: Overview of the Heat Decarbonisation Practices through Heat Pump Technology. Sustain. Energy Technol. Assess. 2021, 48, 101630. [Google Scholar] [CrossRef]
 EC, Horizon 2020, Work Programme for 2016–2017, 10. “Secure, Clean and Efficient Energy”. Available online: https://ec.europa.eu/research/participants/data/ref/h2020/wp/2016_2017/main/h2020wp1617energy_en.pdf (accessed on 3 March 2022).
 Karytsas, S.; Choropanitis, I. Barriers against and Actions towards Renewable Energy Technologies Diffusion: A Principal Component Analysis for Residential Ground Source Heat Pump (GSHP) Systems. Renew. Sustain. Energy Rev. 2017, 78, 252–271. [Google Scholar] [CrossRef]
 Martinopoulos, G.; Papakostas, K.T.; Papadopoulos, A.M. A Comparative Review of Heating Systems in EU Countries, Based on Efficiency and Fuel Cost. Renew. Sustain. Energy Rev. 2018, 90, 687–699. [Google Scholar] [CrossRef]
 Maddah, S.; Goodarzi, M.; Safaei, M.R. Comparative Study of the Performance of Air and Geothermal Sources of Heat Pumps Cycle Operating with Various Refrigerants and Vapor Injection. Alex. Eng. J. 2020, 59, 4037–4047. [Google Scholar] [CrossRef]
 Ninikas, K.; Hytiris, N.; Emmanuel, R.; Aaen, B. Heat Energy from a Shallow Geothermal System in Glasgow, UK: Performance Evaluation Design. Environ. Geotech. 2020, 7, 274–281. [Google Scholar] [CrossRef] [Green Version]
 Ninikas, K.; Hytiris, N.; Emmanuel, R.; Aaen, B. Recovery and Valorisation of Energy from Wastewater Using a Water Source Heat Pump at the Glasgow Subway: Potential for Similar Underground Environments. Resources 2019, 8, 169. [Google Scholar] [CrossRef] [Green Version]
 Hytiris, N.; Ninikas, K.; Aaen, B.; Emmanuel, R. Review of Sustainable Heat in the Glasgow Subway Tunnels. Civ. Eng. Res. J. 2020, 11, 555805. [Google Scholar] [CrossRef]
 Badenes, B.; Sanner, B.; Mateo Pla, M.Á.; Cuevas, J.M.; Bartoli, F.; Ciardelli, F.; González, R.M.; Ghafar, A.N.; Fontana, P.; Lemus Zuñiga, L.; et al. Development of Advanced Materials Guided by Numerical Simulations to Improve Performance and CostEfficiency of Borehole Heat Exchangers (BHEs). Energy 2020, 201, 117628. [Google Scholar] [CrossRef]
 Pezzutto, S.; Grilli, G.; Zambotti, S. European Heat Pump Market Analysis: Assessment of Barriers and Drivers. Int. J. Contemp. Energy 2017, 3, 62–70. [Google Scholar] [CrossRef]
 Blum, P.; Campillo, G.; Kölbel, T. TechnoEconomic and Spatial Analysis of Vertical Ground Source Heat Pump Systems in Germany. Energy 2011, 36, 3002–3011. [Google Scholar] [CrossRef]
 GEOCOND. Available online: https://GeocondProject.Eu/# (accessed on 22 October 2021).
 CheapGahp. Available online: https://CheapGshp.Eu/ (accessed on 22 October 2021).
 Self, S.J.; Reddy, B.V.; Rosen, M.A. Geothermal Heat Pump Systems: Status Review and Comparison with Other Heating Options. Appl. Energy 2013, 101, 341–348. [Google Scholar] [CrossRef]
 Sagia, Z.; Rakopoulos, C. Alternative Refrigerants for the Heat Pump of a Ground Source Heat Pump System. Appl. Therm. Eng. 2016, 100, 768–774. [Google Scholar] [CrossRef]
 Arpagaus, C.; Bless, F.; Schiffmann, J.; Bertsch, S.S. MultiTemperature Heat Pumps: A Literature Review. Int. J. Refrig. 2016, 69, 437–465. [Google Scholar] [CrossRef] [Green Version]
 Sarbu, I.; Sebarchievici, C. General Review of GroundSource Heat Pump Systems for Heating and Cooling of Buildings. Energy Build. 2014, 70, 441–454. [Google Scholar] [CrossRef]
 ASHRAE Geothermal Energy. In ASHRAE HandbookHVAC Applications (SI); Ashrae (American Society of Heating, Refrigerating and Airconditioning Engineers): Peachtree Corners, GA, USA, 2015.
 Staiti, M.; Angelotti, A. Design of Borehole Heat Exchangers for Ground Source Heat Pumps: A Comparison between Two Methods. Energy Procedia 2015, 78, 1147–1152. [Google Scholar] [CrossRef] [Green Version]
 Capozza, A.; de Carli, M.; Zarrella, A. Design of Borehole Heat Exchangers for GroundSource Heat Pumps: A Literature Review, Methodology Comparison and Analysis on the Penalty Temperature. Energy Build. 2012, 55, 369–379. [Google Scholar] [CrossRef]
 Wu, S.; Dai, Y.; Li, X.; Oppong, F.; Xu, C. A Review of GroundSource Heat Pump Systems with Heat Pipes for Energy Efficiency in Buildings. Energy Procedia 2018, 152, 413–418. [Google Scholar] [CrossRef]
 Spitler, J.D. Latest Developments and Trends in GroundSource Heat Pump Technology. In Proceedings of the European Geothermal Congress, Strasbourg, France, 19–23 September 2016. [Google Scholar]
 Calise, F.; Cappiello, F.L.; Dentice d’Accadia, M.; Petrakopoulou, F.; Vicidomini, M. A SolarDriven 5th Generation District Heating and Cooling Network with GroundSource Heat Pumps: A ThermoEconomic Analysis. Sustain. Cities Soc. 2022, 76, 103438. [Google Scholar] [CrossRef]
 Kim, M.J.; Lee, S.R.; Yoon, S.; Jeon, J.S. Evaluation of Geometric Factors Influencing Thermal Performance of Horizontal SpiralCoil Ground Heat Exchangers. Appl. Therm. Eng. 2018, 144, 788–796. [Google Scholar] [CrossRef]
 Pu, L.; Xu, L.; Qi, D.; Li, Y. Structure Optimization for Horizontal Ground Heat Exchanger. Appl. Therm. Eng. 2018, 136, 131–140. [Google Scholar] [CrossRef]
 Li, C.; Mao, J.; Zhang, H.; Xing, Z.; Li, Y.; Zhou, J. Numerical Simulation of Horizontal SpiralCoil Ground Source Heat Pump System: Sensitivity Analysis and Operation Characteristics. Appl. Therm. Eng. 2017, 110, 424–435. [Google Scholar] [CrossRef]
 Jahanbin, A. Thermal Performance of the Vertical Ground Heat Exchanger with a Novel Elliptical Single UTube. Geothermics 2020, 86, 101804. [Google Scholar] [CrossRef]
 Noorollahi, Y.; Saeidi, R.; Mohammadi, M.; Amiri, A.; Hosseinzadeh, M. The Effects of Ground Heat Exchanger Parameters Changes on Geothermal Heat Pump Performance–A Review. Appl. Therm. Eng. 2018, 129, 1645–1658. [Google Scholar] [CrossRef]
 Dewitt, D.P.; Bergman, T.L.; Lavine, A.S.; Incropera, F.P. Fundamentals of Heat and Mass Transfer, 6th ed.; John Wiley & Sons: Hoboken, NJ, USA, 2007. [Google Scholar]
 Zhao, J.; Li, Y.; Wang, J. A Review on Heat Transfer Enhancement of Borehole Heat Exchanger. Energy Procedia 2016, 104, 413–418. [Google Scholar] [CrossRef]
 Aydin, M.; Sisman, A. Experimental and Computational Investigation of Multi UTube Boreholes. Appl. Energy 2015, 145. [Google Scholar] [CrossRef]
 Zarrella, A.; de Carli, M.; Galgaro, A. Thermal Performance of Two Types of Energy Foundation Pile: Helical Pipe and Triple UTube. Appl. Therm. Eng. 2013, 61, 301–310. [Google Scholar] [CrossRef]
 Oh, K.; Lee, S.; Park, S.; Han, S.I.; Choi, H. Field Experiment on Heat Exchange Performance of Various CoaxialType Ground Heat Exchangers Considering Construction Conditions. Renew. Energy 2019, 144, 84–96. [Google Scholar] [CrossRef]
 Gordon, D.; Bolisetti, T.; Ting, D.S.K.; Reitsma, S. A Physical and SemiAnalytical Comparison between Coaxial BHE Designs Considering Various Piping Materials. Energy 2017, 141, 1610–1621. [Google Scholar] [CrossRef]
 Cao, S.J.; Kong, X.R.; Deng, Y.; Zhang, W.; Yang, L.; Ye, Z.P. Investigation on Thermal Performance of Steel Heat Exchanger for Ground Source Heat Pump Systems Using FullScale Experiments and Numerical Simulations. Appl. Therm. Eng. 2017, 115, 91–98. [Google Scholar] [CrossRef]
 Hantsch, A.; Gross, U. Numerical Investigation of PartiallyWetted Geothermal Heat Pipe Performance. Geothermics 2013, 47, 97–103. [Google Scholar] [CrossRef]
 Raymond, J.; Mercier, S.; Nguyen, L. Designing Coaxial Ground Heat Exchangers with a Thermally Enhanced Outer Pipe. Geotherm. Energy 2015, 3, 7. [Google Scholar] [CrossRef] [Green Version]
 Bassiouny, R.; Ali, M.R.O.; Hassan, M.K. An Idea to Enhance the Thermal Performance of HDPE Pipes Used for GroundSource Applications. Appl. Therm. Eng. 2016, 109, 15–21. [Google Scholar] [CrossRef]
 Sliwa, T.; Rosen, M. Efficiency Analysis of Borehole Heat Exchangers as Grout Varies via Thermal Response Test Simulations. Geothermics 2017, 69, 132–138. [Google Scholar] [CrossRef]
 Mahmoud, M.; Ramadan, M.; Pullen, K.; Abdelkareem, M.A.; Wilberforce, T.; Olabi, A.G.; Naher, S. A Review of Grout Materials in Geothermal Energy Applications. Int. J. 2021, 10, 100070. [Google Scholar] [CrossRef]
 Spitler, J.D.; Gehlin, S.E.A. Thermal Response Testing for Ground Source Heat Pump Systems—An Historical Review. Renew. Sustain. Energy Rev. 2015, 50, 1125–1137. [Google Scholar] [CrossRef]
 Badenes, B.; Mateo Pla, M.Á.; LemusZúñiga, L.G.; Sáiz Mauleón, B.; Urchueguía, J.F. On the Influence of Operational and Control Parameters in Thermal Response Testing of Borehole Heat Exchangers. Energies 2017, 10, 1328. [Google Scholar] [CrossRef] [Green Version]
 Zarrella, A.; Emmi, G.; Graci, S.; de Carli, M.; Cultrera, M.; Dalla Santa, G.; Galgaro, A.; Bertermann, D.; Müller, J.; Pockelé, L.; et al. Thermal Response Testing Results of Different Types of Borehole Heat Exchangers: An Analysis and Comparison of Interpretation Methods. Energies 2017, 10, 801. [Google Scholar] [CrossRef] [Green Version]
 Growth in, U.S. Hydrocarbon Production from Shale Resources Driven by Drilling Efficiency. Available online: Https://Www.Eia.Gov/Todayinenergy/Detail.Php?Id=15351# (accessed on 21 May 2018).
 Drilling Efficiency Is A Key Driver of Oil and Natural Gas Production. Available online: Https://Www.Eia.Gov/Todayinenergy/Detail.Php?Id=13651# (accessed on 21 May 2018).
 Zou, D. Theory and Technology of Rock Excavation for Civil Engineering; Metallurgical Industry Press and Springer Science + Business Media: Singapore, 2017. [Google Scholar]
 Yong, Z. Technical Improvements and Application of AirLift Reverse Circulation Drilling Technology to UltraDeep Geothermal Well. Procedia Eng. 2014, 73, 243–251. [Google Scholar] [CrossRef] [Green Version]
 Yao, N.; Yin, X.; Wang, Y.; Wang, L.; Ji, Q. Practice and Drilling Technology of Gas Extraction Borehole in Soft Coal Seam. Procedia Earth Planet. Sci. 2011, 3, 53–61. [Google Scholar] [CrossRef] [Green Version]
 Sliwa, T.; Jarosz, K.; Rosen, M.A.; Sojczyńska, A.; SapińskaŚliwa, A.; Gonet, A.; Fąfera, K.; Kowalski, T.; Ciepielowska, M. Influence of Rotation Speed and Air Pressure on the Down the Hole Drilling Velocity for Borehole Heat Exchanger Installation. Energies 2020, 13, 2716. [Google Scholar] [CrossRef]
 Kim, Y.; Dinh, B.H.; Do, T.M.; Kang, G. Development of Thermally Enhanced Controlled LowStrength Material Incorporating Different Types of SteelMaking Slag for GroundSource Heat Pump System. Renew. Energy 2020, 150, 116–127. [Google Scholar] [CrossRef]
 Lee, C.; Park, S.; Lee, D.; Lee, I.M.; Choi, H. Viscosity and Salinity Effect on Thermal Performance of BentoniteBased Grouts for Ground Heat Exchanger. Appl. Clay Sci. 2014, 101, 455–460. [Google Scholar] [CrossRef]
 Mahmoud, M.; Ramadan, M.; Naher, S.; Pullen, K.; Olabi, A.G. Advances in Grout Materials in Borehole Heat Exchangers. In Encyclopedia of Smart Materials; Olabi, A.G., Ed.; Elsevier: Oxford, UK, 2022; pp. 334–342. ISBN 9780128157336. [Google Scholar]
 Kim, D.; Kim, G.; Kim, D.; Baek, H. Experimental and Numerical Investigation of Thermal Properties of CementBased Grouts Used for Vertical Ground Heat Exchanger. Renew. Energy 2017, 112, 260–267. [Google Scholar] [CrossRef]
 Lee, C.; Lee, K.; Choi, H.; Choi, H.P. Characteristics of ThermallyEnhanced Bentonite Grouts for Geothermal Heat Exchanger in South Korea. Sci. China Technol. Sci. 2010, 53, 123–128. [Google Scholar] [CrossRef]
 Yang, W.; Xu, R.; Yang, B.; Yang, J. Experimental and Numerical Investigations on the Thermal Performance of a Borehole Ground Heat Exchanger with PCM Backfill. Energy 2019, 174, 216–235. [Google Scholar] [CrossRef]
 Delaleux, F.; Py, X.; Olives, R.; Dominguez, A. Enhancement of Geothermal Borehole Heat Exchangers Performances by Improvement of Bentonite Grouts Conductivity. Appl. Therm. Eng. 2012, 33–34, 92–99. [Google Scholar] [CrossRef]
 Do, T.M.; Kim, H.K.; Kim, M.J.; Kim, Y.S. Utilization of Controlled Low Strength Material (CLSM) as a Novel Grout for Geothermal Systems: Laboratory and Field Experiments. J. Build. Eng. 2020, 29, 101110. [Google Scholar] [CrossRef]
 Dinh, B.H.; Kim, Y.; Kang, G. Thermal Conductivity of Steelmaking SlagBased Controlled LowStrength Materials over Entire Range of Degree of Saturation: A Study for Ground Source Heat Pump Systems. Geothermics 2020, 88, 101910. [Google Scholar] [CrossRef]
 Lan, W.; Wu, A.; Yu, P. Development of a New Controlled Low Strength Filling Material from the Activation of Copper Slag: Influencing Factors and Mechanism Analysis. J. Clean. Prod. 2020, 246, 119060. [Google Scholar] [CrossRef]
 Fauzi, M.A.; Arshad, M.F.; Md Nor, N.; Ghazali, E. Modeling and Optimization of Properties for UnprocessedFly Ash (uFA) Controlled LowStrength Material as Backfill Materials. Clean. Eng. Technol. 2022, 6, 100395. [Google Scholar] [CrossRef]
 Wang, K.; Yan, T.; Zhao, Y.M.; Li, G.D.; Pan, W.G. Preparation and Thermal Properties of Palmitic Acid @ZnO/Expanded Graphite Composite Phase Change Material for Heat Storage. Energy 2022, 242, 122972. [Google Scholar] [CrossRef]
 Chen, Y.; Xu, C.; Cong, R.; Ran, F.; Fang, G. Thermal Properties of Stearic Acid/Active Aluminum Oxide/Graphene Nanoplates Composite Phase Change Materials for Heat Storage. Mater. Chem. Phys. 2021, 269, 124747. [Google Scholar] [CrossRef]
 Yan, X.; Zhao, H.; Feng, Y.; Qiu, L.; Lin, L.; Zhang, X.; Ohara, T. Excellent Heat Transfer and Phase Transformation Performance of Erythritol/Graphene Composite Phase Change Materials. Compos. Part B Eng. 2022, 228, 109435. [Google Scholar] [CrossRef]
 Aljabr, A.; Chiasson, A.; Alhajjaji, A. Numerical Modeling of The Effects of MicroEncapsulated Phase Change Materials Intermixed with Grout in Vertical Borehole Heat Exchangers. Geothermics 2021, 96, 102197. [Google Scholar] [CrossRef]
 Wang, T.H.; Yang, T.F.; Kao, C.H.; Yan, W.M.; Ghalambaz, M. Paraffin CorePolymer Shell MicroEncapsulated Phase Change Materials and Expanded Graphite Particles as an Enhanced Energy Storage Medium in Heat Exchangers. Adv. Powder Technol. 2020, 31, 2421–2429. [Google Scholar] [CrossRef]
 Hassan, F.; Jamil, F.; Hussain, A.; Ali, H.M.; Janjua, M.M.; Khushnood, S.; Farhan, M.; Altaf, K.; Said, Z.; Li, C. Recent Advancements in Latent Heat Phase Change Materials and Their Applications for Thermal Energy Storage and Buildings: A State of the Art Review. Sustain. Energy Technol. Assess. 2022, 49, 101646. [Google Scholar] [CrossRef]
 Chen, F.; Mao, J.; Chen, S.; Li, C.; Hou, P.; Liao, L. Efficiency Analysis of Utilizing Phase Change Materials as Grout for a Vertical UTube Heat Exchanger Coupled Ground Source Heat Pump System. Appl. Therm. Eng. 2018, 130, 698–709. [Google Scholar] [CrossRef]
 Li, X.; Tong, C.; Duanmu, L.; Liu, L. Research on UTube Heat Exchanger with ShapeStabilized Phase Change Backfill Material. Procedia Eng. 2016, 146, 640–647. [Google Scholar] [CrossRef] [Green Version]
 Daneshazarian, R.; Bayomy, A.M.; Dworkin, S.B. NanoPCM Based Thermal Energy Storage System for a Residential Building. Energy Convers. Manag. 2022, 254, 115208. [Google Scholar] [CrossRef]
 Masoumi, H.; Haghighi khoshkhoo, R.; Mirfendereski, S.M. Experimental and Numerical Investigation of Melting/Solidification of NanoEnhanced Phase Change Materials in Shell & Tube Thermal Energy Storage Systems. J. Energy Storage 2021, 103561. [Google Scholar] [CrossRef]
 Hayat, M.A.; Chen, Y.; Bevilacqua, M.; Li, L.; Yang, Y. Characteristics and Potential Applications of NanoEnhanced Phase Change Materials: A Critical Review on Recent Developments. Sustain. Energy Technol. Assess. 2022, 50, 101799. [Google Scholar] [CrossRef]
 Javadi, H.; Urchueguia, J.F.; Mousavi Ajarostaghi, S.S.; Badenes, B. Numerical Study on the Thermal Performance of a Single UTube Borehole Heat Exchanger Using NanoEnhanced Phase Change Materials. Energies 2020, 13, 5156. [Google Scholar] [CrossRef]
 Liu, L.; Cai, G.; Liu, X.; Liu, S.; Puppala, A.J. Evaluation of ThermalMechanical Properties of Quartz Sand–Bentonite–Carbon Fiber Mixtures as the Borehole Backfilling Material in Ground Source Heat Pump. Energy Build. 2019, 202, 109407. [Google Scholar] [CrossRef]
 Muraya, N.; O’Neal, D.; Heffington, W. Thermal Interference of Adjacent Legs in a Vertical UTube Heat Exchanger for a GroundCoupled Heat Pump. ASHRAE Trans. 1996, 102, 12–21. [Google Scholar]
 Kim, Y.; Do, T.M.; Kim, M.J.; Kim, B.J.; Kim, H.K. Utilization of ByProduct in Controlled LowStrength Material for Geothermal Systems: Engineering Performances, Environmental Impact, and Cost Analysis. J. Clean. Prod. 2018, 172, 909–920. [Google Scholar] [CrossRef]
 Qi, D.; Pu, L.; Sun, F.; Li, Y. Numerical Investigation on Thermal Performance of Ground Heat Exchangers Using Phase Change Materials as Grout for Ground Source Heat Pump System. Appl. Therm. Eng. 2016, 106, 1023–1032. [Google Scholar] [CrossRef]
 Lashof, D.A.; Ahuja, D.R. Relative Contributions of Greenhouse Gas Emissions to Global Warming. Nature 1990, 344, 529–531. [Google Scholar] [CrossRef]
 Directive (EU) 2014/517 of the European Parliament and of the Council of 16 April 2014 on Fluorinated Greenhouse Gases and Repealing Regulation (EC) 2006/842. Available online: https://eurlex.europa.eu/eli/reg/2014/517/oj (accessed on 3 March 2022).
 MotaBabiloni, A. Analysis of Low Global Warming Potential Fluoride Working Fluids in Vapour Compression Systems. Experimental Evaluation of Commercial Refrigeration Alternatives. Ph.D. Thesis, Universidad Politécnica de Valencia, Valencia, Spain, February 2016. [Google Scholar]
 Thu, K.; Takezato, K.; Takata, N.; Miyazaki, T.; Higashi, Y. Dropin Experiments and Exergy Assessment of HFC32/HFO1234yf/R744 Mixture with GWP below 150 for Domestic Heat Pumps. Int. J. Refrig. 2020, 121, 289–301. [Google Scholar] [CrossRef]
 Bobbo, S.; Di Nicola, G.; Zilio, C.; Brown, J.S.; Fedele, L. Low GWP Halocarbon Refrigerants: A Review of Thermophysical Properties. Int. J. Refrig. 2018, 90, 181–201. [Google Scholar] [CrossRef]
 Makhnatch, P.; Khodabandeh, R. The Role of Environmental Metrics (GWP, TEWI, LCCP) in the Selection Of Low GWP Refrigerant. Energy Procedia 2014, 61, 2460–2463. [Google Scholar] [CrossRef] [Green Version]
 MotaBabiloni, A.; NavarroEsbrí, J.; BarragánCervera, Á.; Molés, F.; Peris, B. Analysis Based on EU Regulation No 517/2014 of New HFC/HFO Mixtures as Alternatives of High GWP Refrigerants in Refrigeration and HVAC Systems. Int. J. Refrig. 2015, 52, 21–31. [Google Scholar] [CrossRef]
 Yang, Z.; Feng, B.; Ma, H.; Zhang, L.; Duan, C.; Liu, B.; Zhang, Y.; Chen, S.; Yang, Z. Analysis of Lower GWP and Flammable Alternative Refrigerants. Int. J. Refrig. 2021, 126, 12–22. [Google Scholar] [CrossRef]
 HerediaAricapa, Y.; BelmanFlores, J.M.; MotaBabiloni, A.; SerranoArellano, J.; GarcíaPabón, J.J. Overview of Low GWP Mixtures for the Replacement of HFC Refrigerants: R134a, R404A and R410A. Int. J. Refrig. 2020, 111, 113–123. [Google Scholar] [CrossRef]
 Bobbo, S.; Fedele, L.; Curcio, M.; Bet, A.; de Carli, M.; Emmi, G.; Poletto, F.; Tarabotti, A.; Mendrinos, D.; Mezzasalma, G.; et al. Energetic and Exergetic Analysis of Low Global Warming Potential Refrigerants as Substitutes for R410A in Ground Source Heat Pumps. Energies 2019, 12, 3538. [Google Scholar] [CrossRef] [Green Version]
 Shen, B.; Ally, M.R. Energy and Exergy Analysis of LowGlobal Warming Potential Refrigerants as Replacement for R410A in TwoSpeed Heat Pumps for Cold Climates. Energies 2020, 13, 5666. [Google Scholar] [CrossRef]
 Emmi, G.; Bordignon, S.; Carnieletto, L.; de Carli, M.; Poletto, F.; Tarabotti, A.; Poletto, D.; Galgaro, A.; Mezzasalma, G.; Bernardi, A. A Novel GroundSource Heat Pump with R744 and R1234ze as Refrigerants. Energies 2020, 13, 5654. [Google Scholar] [CrossRef]
 Wu, W.; Skye, H. Progress in GroundSource Heat Pumps Using Natural Refrigerants. Int. J. Refrig. 2018, 92, 70–85. [Google Scholar] [CrossRef]
 Rawlings, R.H.D.; Sykulski, J.R. Ground Source Heat Pumps: A Technology Review. Build. Serv. Eng. Res. Technol. 1999, 20, 119–129. [Google Scholar] [CrossRef]
 Bartolini, N.; Casasso, A.; Bianco, C.; Sethi, R. Environmental and Economic Impact of the Antifreeze Agents in Geothermal Heat Exchangers. Energies 2020, 13, 5653. [Google Scholar] [CrossRef]
 Emmi, G.; Zarrella, A.; de Carli, M.; Donà, M.; Galgaro, A. Energy Performance and Cost Analysis of Some Borehole Heat Exchanger Configurations with Different HeatCarrier Fluids in Mild Climates. Geothermics 2017, 65, 158–169. [Google Scholar] [CrossRef]
 Liang, B.; Chen, M.; Orooji, Y. Effective Parameters on the Performance of Ground Heat Exchangers: A Review of Latest Advances. Geothermics 2022, 98, 102283. [Google Scholar] [CrossRef]
 Pathak, L.; Trivedi, G.V.N.; Parameshwaran, R.; Deshmukh, S.S. Microencapsulated Phase Change Materials as Slurries for Thermal Energy Storage: A Review. Mater. Today Proc. 2021, 44, 1960–1963. [Google Scholar] [CrossRef]
 Kong, M.; Alvarado, J.L.; Thies, C.; Morefield, S.; Marsh, C.P. Field Evaluation of Microencapsulated Phase Change Material Slurry in Ground Source Heat Pump Systems. Energy 2017, 122, 691–700. [Google Scholar] [CrossRef] [Green Version]
 Pu, L.; Xu, L.; Zhang, S.; Li, Y. Optimization of Ground Heat Exchanger Using Microencapsulated Phase Change Material Slurry Based on TreeShaped Structure. Appl. Energy 2019, 240, 860–869. [Google Scholar] [CrossRef]
 Bobbo, S.; Colla, L.; Barizza, A.; Rossi, S.; Fedele, L. Characterization of Nanofluids Formed by Fumed Al_{2}O_{3} in Water for Geothermal Applications, in Proceedings of the International Refrigeration and Air Conditioning Conference, Purdue University, 11–14 July 2016. Paper 1689. Available online: http://docs.lib.purdue.edu/iracc/1689 (accessed on 3 March 2022).
 Kapıcıoğlu, A.; Esen, H. Experimental Investigation on Using Al_{2}O_{3}/Ethylene GlycolWater NanoFluid in Different Types of Horizontal Ground Heat Exchangers. Appl. Therm. Eng. 2020, 165, 114559. [Google Scholar] [CrossRef]
 Jamshidi, N.; Mosaffa, A. Investigating the Effects of Geometric Parameters on Finned Conical Helical Geothermal Heat Exchanger and Its Energy Extraction Capability. Geothermics 2018, 76, 177–189. [Google Scholar] [CrossRef]
 Diglio, G.; Roselli, C.; Sasso, M.; Jawali Channabasappa, U. Borehole Heat Exchanger with Nanofluids as Heat Carrier. Geothermics 2018, 72, 112–123. [Google Scholar] [CrossRef]
 Du, R.; Jiang, D.; Wang, Y.; Wei Shah, K. An Experimental Investigation of CuO/Water Nanofluid Heat Transfer in Geothermal Heat Exchanger. Energy Build. 2020, 227, 110402. [Google Scholar] [CrossRef]
 Lucia, U.; Simonetti, M.; Chiesa, G.; Grisolia, G. GroundSource Pump System for Heating and Cooling: Review and Thermodynamic Approach. Renew. Sustain. Energy Rev. 2017, 70, 867–874. [Google Scholar] [CrossRef]
 Ma, Z.; Xia, L.; Gong, X.; Kokogiannakis, G.; Wang, S.; Zhou, X. Recent Advances and Development in Optimal Design and Control of Ground Source Heat Pump Systems. Renew. Sustain. Energy Rev. 2020, 131, 110001. [Google Scholar] [CrossRef]
 Yang, H.; Cui, P.; Fang, Z. VerticalBorehole GroundCoupled Heat Pumps: A Review of Models and Systems. Appl. Energy 2010, 87, 16–27. [Google Scholar] [CrossRef]
 Zhang, C.; Wang, Y.; Liu, Y.; Kong, X.; Wang, Q. Computational Methods for Ground Thermal Response of Multiple Borehole Heat Exchangers: A Review. Renew. Energy 2018, 127, 461–473. [Google Scholar] [CrossRef]
 Hou, G.; Taherian, H.; Song, Y.; Jiang, W.; Chen, D. A Systematic Review on Optimal Analysis of Horizontal Heat Exchangers in Ground Source Heat Pump Systems. Renew. Sustain. Energy Rev. 2022, 154, 111830. [Google Scholar] [CrossRef]
 Carnieletto, L.; Badenes, B.; Belliardi, M.; Bernardi, A.; Graci, S.; Emmi, G.; Urchueguía, J.F.; Zarrella, A.; di Bella, A.; Dalla Santa, G.; et al. A European Database of Building Energy Profiles to Support the Design of Ground Source Heat Pumps. Energies 2019, 12, 2496. [Google Scholar] [CrossRef] [Green Version]
 Li, M.; Lai, A.C.K. Review of Analytical Models for Heat Transfer by Vertical Ground Heat Exchangers (GHEs): A Perspective of Time and Space Scales. Appl. Energy 2015, 151, 178–191. [Google Scholar] [CrossRef]
 Hosseinnia, S.M.; Sorin, M. Numerical Approach for Sizing Vertical Ground Heat Exchangers Based on Constant Design Load and Desired Outlet Temperature. J. Build. Eng. 2022, 48, 103932. [Google Scholar] [CrossRef]
 Capozza, A.; Zarrella, A.; de Carli, M. LongTerm Analysis of Two GSHP Systems Using Validated Numerical Models and Proposals to Optimize the Operating Parameters. Energy Build. 2015, 93, 50–64. [Google Scholar] [CrossRef]
 Bahmani, M.H.; HakkakiFard, A. A Hybrid AnalyticalNumerical Model for Predicting the Performance of the Horizontal Ground Heat Exchangers. Geothermics 2022, 101, 102369. [Google Scholar] [CrossRef]
 Chwieduk, M. New Global Thermal Numerical Model of Vertical UTube Ground Heat Exchanger. Renew. Energy 2021, 168, 343–352. [Google Scholar] [CrossRef]
 Li, W.; Dong, J.; Wang, Y.; Tu, J. Numerical Modeling of a Simplified Ground Heat Exchanger Coupled with Sandbox. Energy Procedia 2017, 110, 365–370. [Google Scholar] [CrossRef]
 Li, Z.; Zheng, M. Development of a Numerical Model for the Simulation of Vertical UTube Ground Heat Exchangers. Appl. Therm. Eng. 2009, 29, 920–924. [Google Scholar] [CrossRef]
 Zhou, S.; Chu, X.; Cao, S.; Liu, X.; Zhou, Y. Prediction of the Ground Temperature with ANN, LSSVM and Fuzzy LSSVM for GSHP Application. Geothermics 2020, 84, 101757. [Google Scholar] [CrossRef]
 Zhou, S.; Li, J.; Zhang, Y.; Liu, X.; Zhang, W. Prediction of the Ground Temperature Variations Caused by the Operation of GSHP System with ANN. Geothermics 2021, 95, 102140. [Google Scholar] [CrossRef]
 Xu, X.; Liu, J.; Wang, Y.; Xu, J.; Bao, J. Performance Evaluation of Ground Source Heat Pump Using Linear and Nonlinear Regressions and Artificial Neural Networks. Appl. Therm. Eng. 2020, 180, 115914. [Google Scholar] [CrossRef]
 Chen, S.; Mao, J.; Chen, F.; Hou, P.; Li, Y. Development of ANN Model for Depth Prediction of Vertical Ground Heat Exchanger. Int. J. Heat Mass Transf. 2018, 117, 617–626. [Google Scholar] [CrossRef]
 Atam, E.; Helsen, L. GroundCoupled Heat Pumps: Part 2—Literature Review and Research Challenges in Optimal Design. Renew. Sustain. Energy Rev. 2016, 54, 1668–1684. [Google Scholar] [CrossRef]
 Atam, E.; Helsen, L. GroundCoupled Heat Pumps: Part 1–Literature Review and Research Challenges in Modeling and Optimal Control. Renew. Sustain. Energy Rev. 2016, 54, 1653–1667. [Google Scholar] [CrossRef]
 Javed, S.; Claesson, J. New Analytical and Numerical Solutions for the ShortTerm Analysis of Vertical Ground Heat Exchangers. ASHRAE Trans. 2011, 117, 3. [Google Scholar]
 Noye, S.; Mulero Martinez, R.; Carnieletto, L.; de Carli, M.; Castelruiz Aguirre, A. A Review of Advanced Ground Source Heat Pump Control: Artificial Intelligence for Autonomous and Adaptive Control. Renew. Sustain. Energy Rev. 2022, 153, 111685. [Google Scholar] [CrossRef]
 Xia, L.; Ma, Z.; McLauchlan, C.; Wang, S. Experimental Investigation and Control Optimization of a Ground Source Heat Pump System. Appl. Therm. Eng. 2017, 127, 70–80. [Google Scholar] [CrossRef]
 Xia, L.; Ma, Z.; Kokogiannakis, G.; Wang, S.; Gong, X. A ModelBased Optimal Control Strategy for Ground Source Heat Pump Systems with Integrated Solar Photovoltaic Thermal Collectors. Appl. Energy 2018, 228, 1399–1412. [Google Scholar] [CrossRef] [Green Version]
 Weeratunge, H.; Narsilio, G.; de Hoog, J.; Dunstall, S.; Halgamuge, S. Model Predictive Control for a Solar Assisted Ground Source Heat Pump System. Energy 2018, 152, 974–984. [Google Scholar] [CrossRef]
 Zarrella, A.; Zecchin, R.; de Rossi, F.; Emmi, G.; de Carli, M.; Carnieletto, L. Analysis of a Double Source Heat Pump System in a Historical Building. In Proceedings of the BS2019, 16th International Conference of the International Building Performance Simulation Association IBPSA, Rome, Italy, 2–4 September 2019. [Google Scholar]
Pipe Materials Benchmark: 1.5–2 W/(m·K) [19]  

Conventional solutions  Reference 
Metallic pipes (copper: 395 W/(m·K), steel: 57 W/(m·K)) Thermoplastic polymers (PE, PA, HDPE) 0.2–0.5 W/(m·K)  [9,19,23,44,45] [19,38,45,46] 
Innovative solutions  Reference 
Thermally enhanced HDPE:
 [21,28,30,31] [19,22] [19,22] [38,48] [47] 
Heat pipe BHE  [40] 
Grout materials Benchmark: 2.5–3.3 W/(m·K) [19]  
Conventional solutions  Reference 
Bentonite, Cement: 0.65–0.9, 0.8–1.3 W/(m·K))  [19,21,28,30,43] 
Innovative solutions  Reference 
Thermally enhanced grout:
 [19,50,62,63,64,65] [19,50,63,64,66] [49] 
CLSMs: 1.11–2.35 W/(m·K) PCMs: 0.2–1.52 W/(m·K)
 [60,63,67,68,69,70] [71,72,73] [74,75,76] [77,78] [79,80,81,82] 
Refrigerant  Composition  GWP  Reference 

R410A  R32/R125 (50/50)  2088  
R32  675  [90,96,97]  
R446A  R32/R600/R1234ze(E) (29/3/68)  470  [95] 
R447A  R32/R125/R1234ze(E) (68/3.5/28.5)  583  [93,94] 
R447B  R32/R125/R1234ze(E) (68/8/24)  710  [94,95] 
R452B  R32/R125/R1234yf (67/7/26)  677  [94,97] 
R454B  R32/R1234yf (68.9/31.1)  466  [94,96,97] 
R457A  R32/R1234yf/R152a (18/70/12)  139  [95] 
R459A  R32/R1234yf/R1234ze(E) (68/26/6)  460  [94] 
R463A  CO2/R32/R125/R1234yf/R134a (6/36/30/1414)  1377  [95] 
R466A  R32/R125/R13I1 (49/11.5/39.5)  733  [95] 
ARM20B  R32/R1234yf/R152a (35/55/10)  251  [95] 
ARM71A  R32/R1234yf/R1234ze(E) (68/26/6)  460  [95] 
DR5  R32/R1234yf (72.5/27.5)  490  [93] 
ND  R32*R1234yf*CO2 22/72/6  151  [90] 
Modelling  

Model  Reference  
Thermal response factorbased models Numerical thermal models Artificial neural network models State space models  [112,116,117] [119,120,121,122,123,124] [113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128] [129,130]  
Optimal design  
Model  Reference  
Numerical methods Analytical methods Computational heat transfer approaches Rule/chartbased methods  [129,131] [129,131] [129,131] [28,30]  
Optimal control [113,130,131,132,133,134,135]  
Modelfree
 Modelbased
 Datadriven

Codesign 
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Menegazzo, D.; Lombardo, G.; Bobbo, S.; De Carli, M.; Fedele, L. State of the Art, Perspective and Obstacles of GroundSource Heat Pump Technology in the European Building Sector: A Review. Energies 2022, 15, 2685. https://doi.org/10.3390/en15072685
Menegazzo D, Lombardo G, Bobbo S, De Carli M, Fedele L. State of the Art, Perspective and Obstacles of GroundSource Heat Pump Technology in the European Building Sector: A Review. Energies. 2022; 15(7):2685. https://doi.org/10.3390/en15072685
Chicago/Turabian StyleMenegazzo, Davide, Giulia Lombardo, Sergio Bobbo, Michele De Carli, and Laura Fedele. 2022. "State of the Art, Perspective and Obstacles of GroundSource Heat Pump Technology in the European Building Sector: A Review" Energies 15, no. 7: 2685. https://doi.org/10.3390/en15072685