DOI: 10.1615/ICHMT.2008.CHT
ISBN Print: 978-1-56700-253-9
ISSN: 2578-5486
NUMERICAL AND EXPERIMENTAL STUDY OF GROUND-COUPLED HEAT PUMPS COMBINED WITH THERMAL SOLAR COLLECTORS
ABSTRACT
This paper presents the numerical study of a geothermal heat pump combined with solar collectors using TRNSYS. This system, called GEOSOL, balances domestic hot water (DHW) and a building's heating/cooling energy loads. An experimental study of the process was conducted on a 180-m2 single-family house to validate the numerical model of the process. Two variants of the process were studied. Both variants use solar energy for DHW heating and for injecting heat into the ground. In addition, the first variant also uses solar energy to directly heat the building by heating floor and has a larger area of solar collectors. While taking into account the electric consumption of the circulation pumps, the results show that the overall electric consumption of these two variants is identical : 31 kWh/ m2. Nevertheless, since the heat injected into the ground accounts for 54% of the heat extracted, the first variant can be a better solution to balance thermal ground loads and favour thermal recharging of the ground. The numerical results corresponding to energy consumption are quite similar to the experimental results. This encouraging observation led us to study the suitability of the same GEOSOL process for a 36-flat building using TRNSYS. The results show that a ground-coupled heat pump connected to ten boreholes is perfectly adapted to balancing the heating loads for this type of building. The number of boreholes can be reduced by increasing the area of solar collectors to avoid the slow but inevitable decrease in the ground temperature which penalizes the COP of the entire process.