Flow-dynamics induced thermal management of crude oil wax melting: Lattice Boltzmann modeling

Abstract

The flow dynamics of natural convection during paraffin wax melting is numerically investigated using double-population multi-relaxation-time lattice Boltzmann modeling. Flow dynamics manipulation is achieved using inserts of varying tilt angles θ and positions x*, while the use of insulation material isolates the effects of thermal conductivity enhancement. It is found that improvement in melting duration can reach up to 13%, particularly at low θ and high x* due to restructuring of natural convective currents. Natural convective currents show high potency to enhance melting due to a boost in thermal energy transport and solid-liquid interface progression, especially when the liquid melt phase grows significantly in size. More importantly, the mesoscopic nature of LBM permits natural convective multicellular vortex formation and phase change to naturally manifest themselves, as convective currents rotate in the clockwise direction in multiple degrees of vorticity when melting enhancement occurs. Moreover, the melting process can be expressed in four stages via time-dependent Nusselt number Nu variation. Flow dynamics analysis reveals high natural convective activity, albeit low Nu value even after the four stages of melting process complete early. Overall, the present study may provide new insights into the flow dynamic effects that are underrated knowledge in natural-convective melting, and subsequently would impact the development of available crude oil wax mitigation techniques via thermal management.