air conditioning, geothermal, solar, desiccant assisted, renewable
A research project of the Hamburg University of Technology realizes an open cycle desiccant assisted air conditioning system based on renewable heat sources e.g. solar thermal and heat sinks e.g. shallow geothermal energy. Both advantages of the open cycle process are taken into account, the possible use of a heat sink at higher temperatures and the use of low calorific heat. Moreover, the total system combines additional aspects of an energy efficient air conditioning system e.g. ventilation fan control, a bypass system to reduce extra pressure losses and space heating / cooling. All pumps of the system are frequency controlled and belong to the group of energy-saving pumps. The geothermal system comprises 3 boreholes with a depth of 75 m (246ft) and 5 energy piles with a depth of 14 m (46ft) and supplies the cooling energy for the air conditioning system. A solar thermal system with 20 m² flat panels supplies the low calorific heat. By using space heating e.g. floor heating and the space cooling e.g. floor cooling, cooling beams even more energy can be saved by the separation of cooling and ventilation due to the higher heat capacity of water. This paper presents the results of the demonstration plant for the years 2009 and 2010. The influences of several aspects of an energy efficient air conditioning system combined with a demand oriented control system are presented as well as experiences in dynamic modeling.