Analytic Solution to Predict the Outlet Air States of a Desiccant Wheel with an Arbitary Split Ratio

Abstract

To comprehend the underlying physics of desiccant wheel operation, a feasible analytic solution has been developed from a gas-side resistance model. As a continuation of development, in this study, the analytical model of the previous work is improved by extending the existing model to arbitrary split ratio case. Furthermore, to improve the accuracy for extended operation range of desiccant wheel, the humidity lines on psychrometric chart are separately represented by two gradients, ψp and ψr, from process region and regeneration region. The analytic solution explicitly predicts the temperature and humidity ratio of the outlet air with a simple linear algebra calculation. The outlet air states from the analytical solution are compared with experimental results and with numerical results predicted by a gas-side resistance model according to various design and operation parameters. For various operation condition, the analytic solution demonstrates transient behaviors of the temperature and humidity ratio within the margin of 10% with respect to the root mean square error during whole cycle period, and shows the better prediction in the practical operation range. The simple time-averaged errors, which are more meaningful in practical sense, are surely observed even smaller than the root mean square errors, within 5%.