Rotating Packed Beds (RPBs) are novel reactors used for intensification of mass transfer and mixing since they provide adjustable centrifugal force to simulate high gravity. In this work, in order to analyze and optimize fluid flow in RPBs, a three‐dimensional single‐phase flow was simulated and validated with previous experimental data. The results show that pressure drop increases with an increasing gas flow rate and rotation speed, and reveal the distribution of total pressure and velocity magnitude. A RPB with radial gas inlet, one of the generic types of RPBs, which is widely applied in the chemical industry but has poor gas distribution on the surface of packing, was optimized using various baffles. The width, distance, shape, and opening porosity of the baffles were examined by adopting a criterion, and their effect on gas distribution was illustrated. Finally, a possible optimum structure of the RPB was formulated under optimal operational conditions.

Background Phoebe (Lauraceae) comprises of evergreen trees or shrubs with approximately 100 species, distributed in tropical and subtropical Asia and Neotropical America. A total of 34 species and three varieties occur in China. Despite of economic and ecological value, only limited genomic resources are available for this genus.ResultsWe sequenced the two complete chloroplast (cp) genomes of Phoebe chekiangensis and P. bournei using Illumina sequencing technology via a combined strategy of de novo and reference-guided assembly. We also performed comparative analyses with the cp genomes of P. sheareri and P. sheareri var. oineiensis previously reported. The chloroplast genomes of P. chekiangensis and P. bournei identically contain 112 genes consisting of 78 protein coding genes, 30 tRNA genes, and 4 rRNA genes, with the size of 152,849 and 152,853 bp, respectively. From the two chloroplast genomes, 131 SSRs were identified and 12 different SSRs located in five protein coding genes. The analysis showed the extremely conserved structure of chloroplast genomes with surprisingly little variations at the LSC/IR and SSC/IR boundaries. Moreover, the mean nucleotide diversity was found to be 0.162% for 77 regions, suggesting an extraordinarily low level of sequence divergence. Four highest divergent regions (trnH-psbA, rps14-trnT, petA-psbJ, ccsA-ndhD) with the percentage of nucleotide diversity higher than 0.50% were identified, which had potential use for species identification and phylogenetic studies.ConclusionThis study will facilitate our understanding of population genetics, phylogenetic relationship and plant evolution of Phoebe species.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-017-0192-8) contains supplementary material, which is available to authorized users.

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