Investigation of heat transfer in partially filled horizontal drums

Abstract

The use and the improvement of classical mathematical models for heat transfer in particulate systems can facilitate the industrial large-scale application of rotating drums as bioreactors for solid-state cultivation (SSC). In the current paper, a one-phase two-dimensional heat transfer model is proposed for that radial and angular temperature profiles can be forecasted along time in a horizontal drum, partially filled with glass beads, subjected to intermittent rotation. The most important heat transfer mechanisms were calculated and discussed. Experiments have been carried out in order to provide experimental data of temperature at several radial and angular positions to be compared to the ones predicted by simulation. Three parameters were adjusted to obtain the best fit between simulated and experimental temperature data: hs, hwand k (convective heat transfer coefficient bed surface-headspace, convective heat transfer coefficient wall-to-bed and effective thermal conductivity of the bed, respectively). A factorial central composite design (CCD) was used to optimize the search for the best set of parameters, having the determination coefficient as optimization criteria. For the values of the fitted parameters hs, hwand k, experimental and predicted temperatures were very close, addressing that the model here can be used as a basic feature for further studies of heat transfer in SSC drum bioreactors and other applications.