ABSTRACT
The ground coupled heat pumps with vertical heat exchanger have been known and used for many years. It is also known that if the energy is only extracted or supplied to the ground the heating or cooling performance will drop because of the changes of the lower energy source temperature (Li et al. 2006). Because of the phenomena described above, the idea of the vertical heat exchanger regeneration is examined all over the world. The Underground Thermal Energy Storages (UTES) have chance to be used as the storage of solar and waste energy (Sanner et al. 2003). The multiple tools for the ground temperature fields analysis are constantly developed (Katsura et al. 2008). The simulation research related to the temperature distribution around the vertical heat exchanger are often performed (Li et al. 2009), the models describing the heat exchange in the loop, taking into account the heat exchanger shape and the underground water flow are created (Nam et al. 2008), and the comparative simulations of the long term exploitation of the boreholes in number of configurations, with negligible underground water flow, are also conducted ( Lazzari et al. 2010). The whole systems also become the subject of simulation, both the ones using the heat exchanger regeneration based on the all year round system performance in heating and active cooling mode (Desideri et al. 2011), and the ones
2 MATERIALS AND METHODS
2.2 Ground coupled heat pumps with vertical heat exchangers
A heat pump is a device that transfers the energy from a source that has lower temperature to the receiver, which has higher temperature, using the physical work according to the second law of thermodynamics. Heat pumps are widely used in heating, cooling and heat recovery installations. Nowadays, when the renewable energetics becomes more and more significant, heat pumps are used as devices that may get energy from renewable sources that have low thermal potential (whose temperature prevents their direct use). The simulation research described in the article is related to the ground coupled heat pumps with vertical closed loops in which the water ethylene glycol solvation serves as intermediary agent. Ground serves as good heat source and receiver for a heat pump. The availability of the energy from the ground is in principle coherent to the needs because the ground is wormer than the external air in winter and cooler in summer. The disadvantage of this source is the high investment cost (Szulgowska-Zgrzywa & Fidorów 2011).
