Remarkable enhancement in CNT fiber synthesis by reducing convection vortex in floating catalyst chemical vapour deposition

•The reduction in convection vortex in FC-CVD process achieved by inserting a central heating rod.•Analysis by CFD for optimization of length, position and temperature of the heating rod.•The carbon conversion enhanced by 90% by reducing convection vortex.•50% improvement in aspect ratio and 58% reduction in ID/IG ratio observed.•RTD analysis used for describing the effect of convection vortex on carbon conversion.