Modelling and Experimental Characterization of Solar-Assisted Ground Source Heat Pump Systems with and without Thermal Energy Storage for Cold Climates

Global increase in energy demand and use, including the greenhouse gas emissions associated with the continued use of fossil fuels, has opened research and development of low energy technologies for building heating and cooling. Among the efficient energy technologies and systems developed to enhance efficiency and reduce building carbon footprint, the use of ground source heat pumps (GSHPs) is gaining traction as a cost-competitive, reliable, and environmentally friendly solution. However, in cold climates, like Canada, heating loads are significantly greater than cooling loads, which makes the amount of thermal energy extracted from the ground each year greater than the heat injected back. This can potentially cause ground temperature decline, gradual performance reduction and possibly eventual failure. The associated ground thermal imbalance and the high initial cost of a GSHP are major challenges to the wider adoption of this clean energy technology. In addition, their performance in cold climates has not been widely studied. To address these challenges, the use of solar energy together with GSHP is receiving increasing interest. The optimal design of solar-assisted GSHPs (SAGSHP) can improve performance and reduce the length of ground heat exchangers. The design and performance of SAGSHPs are heavily influenced by the soil conditions, building load characteristics, control optimization, and local climate. These make the design of combined solar thermal energy and GSHPs complicated. There is relatively little information accessible to designers and practicing engineers in designing such systems in extremely cold climates, like those found in Canada. Therefore, this study experimentally and numerically characterizes SAGSHP systems that combine a solar thermal collector with GSHP systems. Field-scale experimental demonstration setup was built and instrumented at the property of an industry partner, Telsec Property Corporation. Furthermore, a thoroughly validated numerical model was developed for long-term performance investigations. User-defined functions were developed and coupled with the model to predict the long-term performance of the system with a realistic dynamic building load profile generated from building energy modelling software. Moreover, the developed model was used to analyze long-term performance of different ground heat exchanger configurations for optimum performance, including single U-tube, conventional double U-tube and a novel inline ground heat exchanger. Furthermore, the long-term effect of ground freezing and groundwater flow on ground temperature recovery and the overall system’s performance, which are mostly neglected in many studies, was investigated. Field-scale experiments and numerical simulations show that solar charging raises fluid temperatures, improves heating COP, and reduces heat pump energy consumption, even in the presence of groundwater flow. The inline ground heat exchanger also outperforms the conventional double U-loop, delivering 4% higher heating COP and annual energy savings. The result from this research is promoting the development of GSHP and SAGSHP in extremely cold climates for sustainable space heating and cooling, contributing to the Canadian net-zero emissions goal. In addition, this research is contributing to the development of reliable computational tools for accurate design of SAGSHP systems for cold climate applications as well as fundamental understanding of subsurface heat transfer and phase change dynamics of water in porous media.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Discipline thesis:degree_discipline

Engineering – Mechanical & Manufacturing

Grantor dc:publisher.institution

Graduate Studies

Year dc:date.issued

2026

Author dc:creator

• Adebayo, Philip Busayo

Advisors dc:contributor.advisor

• Mwesigye, Aggrey
• Mohamad, Abdulmajeed

Committee members dc:contributor.committeemember

• Shor, Roman
• Hugo,Ronald
• Li, Simon
• Cho, Heejin

• cold climates
• vertical ground heat exchanger
• solar-assisted ground source heat pumps
• double U-loop
• thermal balance
• porous media
• heating and cooling
• solar thermal energy storage
• computational fluid dynamics
• field-scale experiments

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

en

DOI

https://dx.doi.org/10.11575/PRISM/51565

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/125145