Controlled falling film heat and mass exchange modules for liquid desiccant air conditioners

Abstract

Academic and commercial research and development of liquid desiccant air conditioning technology has been pursued for several decades. Liquid desiccant air conditioning technology can provide significant benefits in terms of energy consumption and humidity control, particularly in applications where the latent load, energy cost, and operating hours are high. Common problems associated with the heat and mass exchange modules, incorporated into liquid desiccant air conditioners developed to date, include desiccant carryover into the air stream, large size, high cost, lack of scalability, and poor reliability. In addition, useful predictive modeling of latent and sensible heat transfer performance for a given module design is needed to enable equipment designers to properly incorporate the modules into an air conditioning system. These problems have prevented the technology from being more widely adopted at a commercial scale. A novel controlled falling film heat and mass exchange module, which also incorporates low pressure drop particle filtration, has been developed and tested at the laboratory scale and addresses these problems. Further development of the design will enable a broader range of liquid desiccant air conditioning system architectures and applications to be realized with the resultant benefits of improved humidity control, reduced energy consumption, and improved indoor air quality.