Simplified models for the evaluation of desiccant wheels performance

At present interest in building HVAC (Heating, Ventilating and Air Conditioning) systems based on a desiccant wheel is increasing, due to the possibility of realizing high-energy-efficiency systems and of integrating renewable energy sources. The design of air handling units based on this technology is quite complex because of the difficulties in predicting the performance of the desiccant wheel, which is the crucial component of the system. In fact, desiccant wheel performance strongly depends on inlet airflow conditions and on the revolution speed. As a consequence, in HVAC systems, practitioners and engineers mainly prefer to adopt conventional cooling and heating coils, which are well-known components. In this context, the purpose of this chapter is to review and analyse the main simplified models available in literature to calculate desiccant wheels performance. Such correlations can be easily used in worksheets or in energy simulation programs, being a useful tool to compare desiccant wheel-based HVAC systems with conventional configurations.