Mathematical analysis of scaled-size clinker bed for temperature and pressure drop evaluation

Abstract

In order to leverage on existing scaling methodologies, clinker bed was investigated to evaluate its performance for scaled down sizes. Small-sized clinker bed will provide cheaper and faster means of carrying out performance optimization study of clinker cooling process, which has been a research focus in recent years. Heat transfer mathematical equations were adopted to determine the outlet’s temperatures and air pressure drop across the clinker bed, while Buckingham Pi theorem was employed to perform the scaling down of the clinker bed. Findings from the study revealed that for the actual size, predicted air outlet temperature, when compared to the experimental and numerical simulation results from existing literature, produced deviation of –5.46% and +1.65% respectively. For the scaled down-sizes, the air outlet temperature when compared with the actual size of experimental result, yielded deviations of 3.96%, 5.77% and 4.9% because the scaled sizes have 3, 6 and 9 scale factors, respectively. The results further revealed that an increase in mass flow rate of air will improve the heat transfer performance of the clinker bed, but this comes with an increase in pressure drop across the clinker bed heights. Furthermore, an increase in clinker flow rate was observed to be undesirable because the clinker outlet temperature actually being expected to cool down eventually increases, although pressure drop remained unchanged. By adopting a thermal-hydraulic performance factor, maximum percentage deviation between  of the actual size and each scaled size was 0.08% which indicates negligible performance deviation. The study therefore reveals that the size of clinker bed can be reduced to enable the development of small-scale prototype, and for numerical simulation to optimize the cooling process, especially when the outlet temperature and air pressure drop are the primary targets of investigation.