Elucidation of hydrodynamics and heat transfer characteristic of converging and equivalent uniform riser for dilute phase gas–solid flow

Abstract

An investigation on the influence of a riser geometry on gas–solid hydrodynamics and heat transfer in dilute phase vertical pneumatic conveying system was studied using a simplified one-dimensional simulation program. Risers of equivalent uniform and converging diameters were considered for the comparative studies. The effects of riser shape on gas velocity, relative velocity, Reynolds number, pressure drop, and heat transfer coefficient is also investigated. The effect of convergence angle on total pressure drop and gas–particle heat transfer has been also studied. The significant findings of the present study shows that the converging shape of the riser enhances the gas–particle heat transfer due to higher gas–particle Reynolds number. The heat transfer coefficient and pressure drop is 0.6146W/m2 K and 415N/m2 for converging riser and 0.3938W/m2 K and 364N/m2 for uniform diameter riser. A cost estimation on the net energy benefit has been also done and found 20.67% improvement of heat recovery by solids at the expense of additional 14.02% of pumping energy by using converging riser in place of uniform diameter riser. Thus it can be revealed that the converging riser can enhance the gas–solid heat transfer and hydrodynamics parameter.