Analytical solution for heat and mass transfer in desiccant coated heat exchangers

Abstract

• Heat and moisture transfer in a desiccant-coated heat exchanger (DC-HX) is studied. • A new closed-form analytical solution is proposed. • Linear and exponential profiles are assumed for air temperature and humidity ratio. • A new DC-HX coated with AQSOA™-FAM-Z02 is also fabricated and tested. Due to the complicated nature of desiccant-coated heat exchangers (DC-HXs), solving the highly-coupled transient heat and mass transfer equations using numerical simulations are rather time-consuming and as a result may be impractical for real-time system optimization and seasonal simulations. On the other hand, the approach of majority of studies associated with DC-HXs is numerical and experimental analyses and there is no analytical model that can accurately predict the heat and moisture transfer in a DC-HX in the literature. Thus, in this paper, a new closed-form analytical solution is proposed to accurately predict the heat and moisture transfer in a DC-HX for the first time. The governing equations are simplified to a set of linear ordinary differential equations with initial conditions and then solved analytically. In the present analytical model, both linear and exponential profiles are assumed for the air temperature and humidity ratio along the DC-HX and the results are compared to experimental data collected in our lab. A new DC-HX coated with AQSOA™-FAM-Z02 is also fabricated and tested in our custom-built testbed under a wide range of operating conditions for model validation and performance assessment. Our results indicate that the present analytical solution with exponential profile assumption predicts the experimental data with an average relative difference of less than 10%, while the linear profile assumption results in a relative difference of ∼ 20% with the experimental data. The new analytical solution is capable of predicting the performance of DC-HXs, which is crucial for design, optimization and operating dehumidification systems in a variety of applications.