A Desiccant Assisted Air Conditioning System with Use of Geothermal Energy

Abstract

During summer, the use of conventional electrically driven air conditioning systems often results in high electricity consumption. On the other hand, heat demand is very low, so heat from solar collectors or from Combined Heat and Power plants (CHP) cannot be used. Thermal driven desiccant assisted air conditioning systems offer the possibility to shift energy requirements from electricity to heat. Furthermore, as sorptive pre-drying air does not require cooling under the dew point for dehumidifying or any subsequent heating, cold sources at higher temperatures (e.g. 18°C) can be used for cooling (e.g. shallow geothermal energy).

A research project from the Hamburg University of Technology combines a desiccant assisted air conditioning system with shallow geothermal energy. The geothermal system comprises 3 boreholes and 5 energy piles and supplies the cooling energy for the air conditioning system. The authors regard the two systems as a whole and focus on the combination as well as the interaction between them. The study and the numerically simulation of the heat injection rate of ground source heat exchanger and the air-cooling in rooms are part of the research. It is found that the combination of desiccant wheels and earth energy systems yields considerable energy savings compared to conventional electric systems. Furthermore, a combination with solar thermal energy allows a sustainable air conditioning system.