Run-Around Energy Recovery System for Air-to-Air Applications Using Cross-Flow Exchangers Coupled with a Porous Solid Desiccant—Part II: Results and Performance Sensitivity

Abstract

The model for the run-around energy recovery system was developed and verified for sensible and latent energy transfer in Part I (Li et al. 2009). In this paper, the sensible, latent, and overall effectiveness are investigated in each exchanger as well as the run-around exchanger. The overall effectiveness of the run-around energy recovery system is dependent on the airflow rate, the solid desiccant flow rate, the desiccant properties, specific surface area, the size of each exchanger, and the inlet air operating conditions. The run-around system can achieve a high overall effectiveness when the flow rates and exchanger's properties are properly chosen. Comparisons between the solid desiccant and salt solution run-around system effectiveness (Fan et al. 2006) show they are in agreement. In a sensitivity study, the thickness of desiccant on the fiber is investigated in the solid run-around system. It was found that a good performance is obtained with very thin desiccant coatings (1 or 2 μm). During the practical use of this system, a desiccant-coated fiber could be inserted into very porous balls or cages, protecting the desiccant-coated fiber from mechanical wear. The performance sensitivity for this kind of run-around system is demonstrated.