伊拉克某油田注水站设计方案优化

伊拉克鲁迈拉油田CP00注水站设计规模为1 000 m3/h,注水压力为20 MPa。该注水站的设计方案及优化考虑了安全、环保、节能、节省投资等因素。重点介绍了CP00内向注水泵喂水的方案选择及设计优化,以及整体工艺流程的设计。     

食品防腐剂的使用现状及安全性分析

食品防腐剂主要用于抑制微生物的生长繁殖,以延长食品的保存期。分析了我国食品防腐剂的使用现状、常用的防腐剂的种类及性能、防腐剂使用中存在的问题及安全性评价指标,提出了安全使用防腐剂的建议。     

Computational fluid dynamics (CFD) investigation of air flow and temperature distribution in a small scale bread-baking oven

Experimental and computational fluid dynamics (CFD) analyses of the thermal air flow distribution in a 3-zone small scale forced convection bread-baking oven are undertaken. Following industrial bread-making practise, the oven is controlled at different (constant) temperatures within each zone and a CFD model is developed and validated against experimental data collected within the oven. The CFD results demonstrate that careful selection of the flow model, together with implementation of realistic boundary conditions, give accurate temperature predictions throughout the oven. The CFD model is used to predict the flow and thermal fields within the oven and to show how key features, such as regions of recirculating flow, depend on the speeds of the impinging jets.     

Electrokinetic flow in connected channels: a comparison of two circuit models

We apply the recently developed ‘ion current model’ (ICM) to investigate mixed pressure-driven/electro-osmotic flow in electrokinetic series circuits. Under the ICM, the local geometric mean ion concentration varies throughout a microfluidic circuit as a consequence of ion conservation. ICM predictions are used to assess the accuracy of the earlier ‘total current model’ (TCM), which is instead based upon the simplifying assumption that the geometric mean ion concentration is uniform in all channels within a circuit. The model comparison is performed over an experimentally relevant range of physical parameters and channel dimensions. When the ratio of total current to flow rate is small, or when the inlet concentration is very low or very high, the ICM and TCM give similar predictions of the total pressure and potential differences across simple three-channel contraction–expansion networks. Otherwise, the errors introduced using the TCM may be very large. Our results demonstrate that the common assumption that the electrolyte concentration throughout a device is equal to the concentration of fluid supplied to the device is not always valid, even if there is little or no electric double layer overlap.     

Commentary: The Library and the Laurentian Enigma

Abstract

Students played a significant part in the growing influence of modernism at American design schools between the First and Second World Wars. At several universities, students led a spirited campaign to replace beaux arts teaching methods with a curriculum based on modernist principles. This essay focuses on the University of California, Berkeley, where activist students advanced their cause by meeting with top university administrators and by publishing a magazine critical of their program. The students' desire for modernism was fueled not only by aesthetic trends in the design profession, but from their involvement in leftist political and social movements that swept campuses in the 1930s. For many students, modernism offered a set of tools for improving the lives of Americans during the Great Depression. The student activity at Berkeley ultimately led to a gradual shift away from beaux arts methods at the school and it hastened a search for a modernist architect to take over the design program.     

VOLUME-OF-FLUID CALCULATION OF HEAT OR MASS TRANSFER ACROSS DEFORMING INTERFACES IN TWO-FLUID FLOW

A new volume-of-fluid (VOF)-based numerical method for calculating heat transfer or mass transfer of a species within and between fluids with deforming interfaces is described. The algorithm is tested first against an analytical solution for diffusion from a sphere, and good agreement between theory and calculation is shown. The method is then demonstrated by predicting (a) heat transfer from a rising bubble when the bubble forms a toroidal shape, and (b) mass transfer from a rising drop when the drop phase controls diffusion. The method is shown to be a viable approach for complex interfacial heat/mass transfer.