Article Highlights• Effect of shrinkage during fluidized bed drying of orthodox broken type tea particles was studied • Shrinkage of tea particles was correlated between two dimensionless numbers • New model was developed to predict minimum fluidization velocity considering the shrinkage effect • Results were validated for continuous fluidized bed drying of orthodox broken type tea Abstract Fermented tea particles (dhool) are a polydisperse system subject to shrinkage during fluidized bed drying, which is an important process in the production of orthodox broken type tea. The effect of shrinkage on the physical properties and the minimum fluidization velocity were studied. Five different moisture contents of dhool particles were chosen in the range of 3-106 mass% (dry basis) and the changes in particle diameters and particle densities were measured. For each of the moisture contents, the minimum fluidization velocity was found for three different bed loadings using ambient air at 25 °C in a fluidized bed with an area of 351×345 mm 2 . Since the conventional industrial type fluidized bed dryers operate at 124 °C, the new correlations among the Archimedes number, Reynolds number at minimum fluidization and dimensionless moisture content were developed using air properties at 124 °C. The results were validated for orthodox broken type tea, drying at 124 °C, in a fluidized bed dryer with bed loadings in the range of 44.5 to 50.5 kg/m 2 . The predicted fluidization velocity was found to be in good agreement with the experimental data and the difference was below 10% for most cases.Keywords: fluidized bed drying, minimum fluidization velocity, orthodox broken type tea, shrinkage.Fluidized bed drying is an extensively used process for drying solid particles in the current process industry where a hot fluid is uniformly passed upwards through a bed of wet solid particles with a flow rate enough to make the bed behave like a liquid. The process is highly advantageous due to its high thermal efficiency, ease of operation, low construction cost and large capacity [1]. Hence, this process is used for drying fermented tea particles (dhool) during