Comparison between the performance of sensible and total heat recovery devices and a liquid desiccant twin-tower system
MetadataShow full item record
A significant share of the energy demand in high performance buildings is related to mechanical ventilation. Aside traditional heat recovery devices, liquid desiccant systems can play an important role. The performance of liquid desiccant devices and consequently their potential in energy savings is complex to estimate due to the influence of operational conditions as well as of the physical properties of the fluids. A simple twin-tower configuration has been proposed as a reference system for assessing the control strategy and the potential of this technology to reduce the ventilation load. It consists of one absorption tower that treats the outside air and a second one that uses the exhaust air to restore the initial liquid desiccant conditions. This configuration operates as a total heat exchanger between the fresh and exhaust airstreams, with the liquid desiccant as heat and mass transfer medium. The heat and mass transfer between the fluid flows in the two towers has been modelled, and the energy saving potential in heating and cooling mode has been calculated based on annual hourly weather data. In order to assess the results, a comparison with the saving potential from conventional sensible and total heat recovery systems have been performed, considering 9 locations across Europe. Control strategies have been considered to limit total heat recovery in order to prevent excessive indoor humidity and/or to minimize dehumidification by cooling, comparing different room and ventilation conditions.