Evaluation of ionic liquids as new working pairs in Liquid Desiccant Systems for air conditioning

The EU building directive (“Near Zero Energy Buildings”) requires high building standards, which in turn demand high impermeability of buildings and the use of technologies such as heat and moisture recovery systems. Ventilation systems with integrated air conditioning are therefore a key technology. Surveys predict a growth of the total electricity consumption for ventilation and air conditioning in Austria by a factor of five until 2030 (reference 2005). It is therefore important to develop and use technologies and systems which enable high efficiencies and the use of renewable energy sources. A potential technology is sorption systems for air condition, so-called “Desiccant systems”. An energetically especially advantageous concept are Liquid Desiccant Systems (LDS) based on liquid sorbents. Beside their high efficiency, LDS can additionally store cooling energy and moisture which decouples energy supply from demand. This enables load balancing.

Despite all these benefits, LDS are not established on the market yet. The main reason is that today’s working agents are based on salt solutions. In combination with air-oxygen corrosion occurs. In order to alleviate this problem expensive materials have to be used. Another problem is limited operation ranges due to crystallization limits. These fundamental problems can be overcome by new working agents based on ionic liquids. To study this interesting application area is the main focus of this project.  An essential part of this study will be the performance evaluation of ionic fluids in LDS by experiments and simulations. Furthermore, an in-depth analysis of present LDS will be undertaken. Based on these results, the technological and economic potential of LDS with ionic fluids can be specified. The project results will allow to quantify technological and economic risks and prospects of this innovative approach. This is the prerequisite in order to develop a business case for a new product.

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This project is funded partly by the Climate and Energy funds and is implemented in the context of the programme "Neue Energien".