The present study focuses on enhancing fluidization capacity and optimizing a lab-scale gas-solid vortex reactor (GSVR) without-slit numerically. This reactor has been developed without-slit, and the air-inlets of the rectangular cross-section are used instead of circular cross-section. The numerical investigation has been carried out to analyze two fluids (gas-solid) flow patterns and heat transfer phenomena in GSVR without-slit, using a commercial software ANSYS FLUENT 14.5 by implementing Eulerian-Eulerian approach for gas-solid phases. In the present study, numerical simulations have been carried out for distinct length to diameter ratios (L/D) of 0.2, 0.8, 1.0, and 1.2, assuming the same chamber diameter of 240 mm. In contrast, the chamber diameter is fixed to 240 mm. Hence, the reactor capacity of lab scale GSVR reactor is enhanced from 500 g to 3370 g by increasing L/D of 0.2 to 1.2.