A New Method for Determining the Nusselt and Sherwood Numbers in Simultaneous Heat and Mass Transfer in Solar Collector/Regenerators
Abstract
Despite the numerous studies conducted in last decades with solar collector/regenerators (C/Rs), there is still a lack of consistency in how to calculate their Nusselt and Sherwood numbers, since the available correlations are restricted to specific geometries, liquid desiccants and operating parameters, thus resulting in different values for similar equipment even under same conditions. This paper presents a new evaluation method based on the thermophysical properties of liquid and gas phases, the latent heat of evaporation and specific heat of dilution during phase change, temperature and mass concentration gradients, single-phase convective heat and mass transfer coefficients and system geometry obtained from own experimental data and those reported by Alizadeh and Saman (2002a), Li and Yang (2010) and Peng and Zhang (2015; 2016). These expressions greatly outperform existing approaches, being then reliable for accurately simulating the coupled heat and mass exchanges within forced-flow direct solar regenerators.