Abstract :

In this paper, a novel design of hybrid stationary packed solid desiccant bed is proposed and numerical simulation of the performance for drying of gases is presented. The pro-posed hybrid packed beds is consists of a mixture of solid desiccants of different types having both fixed and varying particle diameter distribution along the vertical axis direction. Generally in the beds of this type, the drying time taken for the bed saturation is hugely related to the input condition of the gases. Also, the adsorption isotherm curves of different desiccant types have a strong effect on the exit conditions of the gases dehumidified/dried using these beds. In order to simulate the transport phenomena associated with the hybrid packed solid desiccant bed application, an in-house CFD code using finite volume method is developed. This CFD code has the capability to model the simultaneous heat conduction and moisture diffusion taking place in the bed during the gas transport. The numerical results of the base model design are validated against the experimental data available in the literature. The estimated exit temperature and moisture content of the gas is in good agreement with the literature data. Further, the validated model is used to simulate for several other novel packed bed designs, the coupled heat and mass transfer in adsorption and desorption phases under wide operating conditions. The results of interest includes the assessment of improvement in performance of dehumidifying/drying of gases in terms of pressure dew point, relative humidity at exit and the prediction of the desorption phenomena for the regeneration of the beds for the next cycle of operation. Finally, the paper summarizes the benefits of this novel hybrid design and highlights the potential design cost-benefit.