IN-24-C023 - Comparison of Different Desiccant Wheel Modeling Methods: A Review and Case Study

Dehumidification is a critical air-conditioning process in heating, ventilation, and air-conditioning (HVAC) applications, especially in hot and humid climates. It is energy-intensive and strongly impacts the indoor air quality in the conditioned space. Dehumidification through desiccant wheels has been widely used in modern HVAC systems. The performance of the desiccant wheel is strongly dependent on the sizing and operation strategies. It is acknowledged that a model of desiccant wheel can be used to facilitate the analysis of the desiccant wheel’s performance in various operating conditions as well as providing guidelines for the design, operation, and optimization of desiccant wheel at the system level. This study aims to summarize the state-of-the-art of desiccant wheel modeling technique to assist research and development of desiccant wheels for HVAC applications. An overview of the existing methods of modeling the desiccant wheel is first introduced, including the performance curve-based empirical model used in EnergyPlus, the effective method used in TRNSYS, the physics-based model using mass and energy conservation equations, and the data-driven simplified model. Desiccant characteristics, including equilibrium relations, adsorption heat, etc., all have a significant influence on the heat and mass transfer process, and therefore they are summarized as well. Modelica-based models of the desiccant wheel are developed based on the empirical approach using the performance curves and the physics-based equations. Those two models are further verified and validated using the simulated data from EnergyPlus and data from the literature.