Numerical simulations of heat transfer in a packed column: comparison of microwave and convective heating

Abstract

This paper presents a comparative study on heat transfer in a packed column. Two methods of heating are considered: microwave and convective. Transient onedimensional mathematical models were proposed to describe the both alternatives. To account for significant differences in the temperatures between the gas and solid phase a heterogeneous model was applied in the modelling. The numerical simulations were carried out for different operating conditions. The effects of the gas inlet temperature and the microwave power, the bed porosity, the penetration depth of microwaves and the gas velocity were examined. The simulation results were compared on the basis of the time profiles of the average bed temperature and the outlet gas temperature. The same electric power utilized in the microwave heated packed column and the convective heated packed column was established as the key criterion for the comparisons. The compared profiles intersect indicating the time ranges in which the one or the other solution provides higher temperature of the bed. It was displayed that the microwave heated packed column should be preferred when longer heating times are required. In turn, the convective heated packed column is the better choice when shorter heating times are needed.

Laser induced graphitization of PAN-based carbon fibers

“…[3][4][5] In this type of furnace, CFs were heated indirectly via convective and irradiative heat transformation under inert gas protection, resulting in a slow heating rate, short life time of heating units as well as huge waste of energy. 6,7 During the past years, irradiation methods have attracted increasing interest and considerable efforts were paid to the irradiation of CFs. For example, electron, 8 plasma, 9 ion 10 and microwave 11 etc.…”