An experimental work on the performance of a solar-assisted ground-coupled heat pump using a horizontal ground heat exchanger

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Solar Assisted Ground Coupled Heat Pumps are thoroughly investigated today. Although the best method to extract heat from the earth is by using vertical ground heat exchangers, they are expensive. Horizontal ground heat exchangers are cheaper but the downside is that they are not so efficient. The main objective of this study is to find efficient, alternative methods to assist the horizontal ground heat exchanger in order to decrease the ground freezing period and increase its performances. For that, a Solar Assisted Ground Coupled Heat Pump system was established, using two solar assistance sub-systems (solar thermal panels and solar photovoltaic panels). A third heat source was considered, consisting in the residual heat lost from the building's heated basement. The results indicated that using auxiliary heat sources eliminated the ground freezing period. Although heat transfer into the Horizontal Ground Heat Exchanger increased the Seasonal Performance Factor by approximative 15% for the season peak, a high amount of heat was lost in the process. This study also addresses possible methods to reduce the heat loss. Overall, the results indicated better performance for the Horizontal Ground Heat Exchanger when transferring heat into it.