The influence of ground heat exchanger installation on the efficiency of residential geothermal ventilation systems

Geothermal ventilation is used for preheating outdoor air in the cold season and pre-cooling it in the warm season using a mechanical ventilation system. It allows the building to save on traditional fuels when preheating or cooling outdoor supplied air by using low-potential soil heat. Air and soil exchange heat through the walls of the ground heat exchanger. Ground heat exchangers for geothermal ventilation can be installed in the ground according to a ring scheme, a Tichelmann scheme, or with a coil scheme. This article focuses on the geothermal ventilation system of a residential building using two methods of installing ground heat exchangers. The thermal energy performance of ground heat exchangers when laid in a coil format and in the Tichelmann scheme was compared. The operation of the variants was simulated using REHAU-GAHE software. As the calculation results showed, the thermal energy performance of the system for the two types of installation is approximately the same, since the program is set to maintain the minimum temperature at the outlet of the ground heat exchanger. For example, the amount of heat received per year for a ground heat exchanger installed in a coil format is 7310.22 kWh/year, and for a ground heat exchanger installed according to the Tichelmann scheme – 7430.35 kWh/year. As for the geometric dimensions, the results obtained are significantly different. Thus, for an installation depth of 2.5 m when installed in a coil format, the pipeline diameter was 500 mm and the length was 168 m, and when installed according to the Tichelmann scheme – the diameter was 250 mm and the length was 403 m.