Parametric investigation of spray drying Na2Fe0.6Mn0.4PO4F/C cathode material: evaluating heat and mass characteristics

The experimental investigation on the interaction between the spray distribution and the heat and mass transfer parameters during spray drying of cathode electrode materials remain limited. This gap restricts the estimation of occurrence of regions of droplet evaporation and solid particle drying. An attempt is made to delineate these regions by mapping the temperature profiles obtained from 20 T-type thermocouples positioned at axial and radial positions within the spray drying chamber. The material Na 2 Fe 0.6 Mn 0.4 PO 4 F/C is utilized for the experiments. Using a volumetric approach, volumetric heat ( h V ) and mass transfer coefficient ( k V ), volumetric Nusselt number ( Nu V ), and Sherwood number ( Sh V ) are evaluated. The aforementioned parameters are evaluated for orifice diameter ( d 0 ) between 0.2 and 0.7 mm, feed solution injection pressure ( P IN ) between 2 bar and 7 bar, hot air inlet velocity ( V IN ) of 0.88 m/s and 1.18 m/s, and hot air inlet temperature ( T IN ) of 250 °C and 300 °C. The experimental results estimate that the spray penetration length ( L P ) is between 100 and 500 mm, with k V ranging from 3 to 27 s −1 , Nu V from 600 to 3700, Sh V from 38 to 2300, and h V from 4.5 to 26 kWm −3 K −1 . The spray cone angle ( θ ) is determined by visualization techniques and it ranges from 45° to 80°. This work establishes design correlations between the spray distribution and heat and mass transfer parameters and future work will integrate moisture content and particle size distribution.