Process integration techniques for optimizing seawater cooling systems and biocide discharge

This work addresses the problem of using seawater for cooling and the associated environmental problems caused by the usage and discharge of biocides. The discharged biocide and its byproducts are toxic to aquatic lives and must be decreased below certain discharge limits on load prior to discharge. The conventional approach has been to add biocide removal units as an end-of-pipe treatment. This work introduces an integrated approach to reducing biocide discharge though a set of coordinated strategies for in-plant modifications and biocide removal. In particular, process integration tools are used to reduce heating and cooling requirements through the synthesis of a heat-exchange network. Heat integration among process hot and cold streams is pursued economically by reconciling cost reduction in utilities versus any additional capital investment of the heat exchangers. Other strategies include maximization of the temperature range for seawater through the process and optimization of biocide dosage. This new approach has the advantage of providing cost savings while reducing the usage and discharge of biocides. A case study is used to illustrate the usefulness of this new approach and the accompanying design techniques.     

纳滤法除盐研究

利用纳滤膜对自来水、模拟苦咸水以及某含有机物废水进行了试验。通过改变浓缩液与透过液的流量比，测量盐分的截留率和水通量等参数，得到了纳滤膜在除盐时的一些规律。     

A desalination battery

Water desalination is an important approach to provide fresh water around the world, although its high energy consumption, and thus high cost, call for new, efficient technology. Here, we demonstrate the novel concept of a "desalination battery", which operates by performing cycles in reverse on our previously reported mixing entropy battery. Rather than generating electricity from salinity differences, as in mixing entropy batteries, desalination batteries use an electrical energy input to extract sodium and chloride ions from seawater and to generate fresh water. The desalination battery is comprised by a Na(2-x)Mn(5)O(10) nanorod positive electrode and Ag/AgCl negative electrode. Here, we demonstrate an energy consumption of 0.29 Wh l(-1) for the removal of 25% salt using this novel desalination battery, which is promising when compared to reverse osmosis (~ 0.2 Wh l(-1)), the most efficient technique presently available.     

增强现实儿童识字卡片设计研究

目的 研究增强现实(简称AR)儿童识字卡片的设计方法,促进儿童识字教育产品的创新发展。方法 对识字教育产品设计现状、VR/AR技术在儿童教育领域的研究现状进行梳理,分析AR技术应用于儿童教育的特性及优势,并结合儿童群体特征和科学识字早期相关研究对设计策略进行探讨,结合情境学习理论,以“恐龙”主题识字卡片设计为例,研究AR识字卡片的设计方法:通过多维度的功能设计、能渲染情境认知氛围的卡片设计、逼真有趣的三维模型和动画,以及情智交融的交互设计,构建出有助于儿童学习的AR情境,从而提高儿童的学习兴趣,增强学习效果。结果 得到了能融合AR情景的儿童识字卡片设计方法,并使用Unity三维引擎和Vuforia插件进行了设计验证。结论 设计实例能引导孩子主动学习,可以达到增强其学习效果的目的,不仅为同类儿童教育类产品的设计提供了参考,也为互动媒体技术背景下的儿童教育提供了更多可能。     

纳滤膜在海水淡化中的应用研究

海水淡化是解决淡水危机的主要方法之一,但由于海水的硬度、浊度和总固溶物含量均非常高,因而导致淡化水的能耗量和成本较高.本文采用纳滤膜法处理海水,考察纳滤膜分离性能随操作压力、操作温度、时间、水回收率等变化的影响及纳滤膜运行的稳定性.结果表明,采用纳滤膜技术可以降低海水的硬度和总固溶物的含量,减少结垢与污染,提高水回收率,有望实现海水淡化成本的进一步降低.     

海水淡化的成本

简要介绍几种主要海水淡化方法－多级蒸,多效蒸馏和反渗透的投资费,能耗及其淡化水的总成本,在市场竞争中,海水反渗透淡化法近来的市场占有发过其他的方法,海水反渗透的能耗进一步下降到3kW.h/m^3左右,淡化水的成本也几乎下降了一半,即0．55$/m^2以下,预计21世纪的海水淡化市场会有很大发展。     

Salcon secures desalination contract

Boustead Singapore Ltd’s subsidiary Salcon Ltd has been awarded a contract by Senoko Power Ltd to design, construct and commission a sea-water desalination plant at one of the company’s largest power stations in Singapore.This is a short news story only. Visit www.filtsep.com for the latest filtration industry news.     

Optimal design of a district cooling grid: structure,technology integration,and operation

The concept of a district cooling grid that allows the integration of several cooling technologies with different availability and supply patterns is introduced. An integrated multi-period optimization model for a district cooling grid configuration is developed. An approximate decomposition strategy is proposed to aid in the efficient design of large grids. Results of extensive computational study are provided that demonstrate the solvability of the developed model to optimality and the effectiveness of the proposed decomposition strategy as a viable solution approach.     

Holey graphene hydrogel with in-plane pores for high-performance capacitive desalination

Capacitive deionization is an attractive approach to water desalination and treatment.To achieve efficient capacitative desalination,rationally designed electrodes with high specific capacitances,conductivities,and stabilities are necessary.Here we report the construction of a three-dimensional (3D) holey graphene hydrogel (HGH).This material contains abundant in-plane pores,offering efficient ion transport pathways.Furthermore,it forms a highly interconnected network of graphene sheets,providing efficient electron transport pathways,and its 3D hierarchical porous structure can provide a large specific surface area for the adsorption and storage of ions.Consequently,HGH serves as a binder-free electrode material with excellent electrical conductivity.Cyclic voltammetry (CV) measurements indicate that the optimized HGH can achieve specific capacitances of 358.4 F.g-1 in 6 M KOH solution and 148 F.g-1 in 0.5 M NaC1 solution.Because of these high capacitances,HGH has a desalination capacity as high as 26.8 mg.g-1 (applied potential:1.2 V;initial NaCl concentration:～5,000 mg.L-1).     

纳米碳管与活性炭复合电极电吸附脱盐性能的研究

为考察纳米碳管（CNTs）、活性炭（AC）及其复合电极的电吸附脱盐性能，将其粉末压制成电极，组装成脱盐器，比较电极电吸附脱盐能力和脱盐能耗。结果表明，在活性炭电极中添加纳米碳管有效地降低了电极电阻和脱盐能耗，少量纳米碳管的添加能在一定程度上提高其电极比表面积、孔容以及在盐水中的比电容；当复合电极中纳米碳管的含量为10％时，其电极在盐水中的电吸附比电容达到113.5F/g，其电极脱盐效果最为显著，其脱盐耗能比活性炭电极降低约67％左右。     

Computer Augmented Oscilloscope System

The Computer Augmented Oscilloscope System (CAOS) is a laboratory-computer terminal intended for experiments involving waveforms and their interpretation. The terminal is portable and can be used wherever telephone access to a suitably programmed computer is available. The CAOS laboratory equipment includes a sampling oscilloscope with a storage CRT, the terminal proper, and a telephone line connection. The terminal includes alphameric and function keyboards, A/D and D/A converters, a read-only store character generator, sequencing and control logic, and circuits for interfacing to the oscilloscope and the telephone line. CAOS is an interface between the experimenter, the experiment, and the computer. It provides digital acquisition of waveform data, system calibration, data analysis, experiment control, and graphic and alphameric display. CAOS can emulate a number of laboratory instruments and can operate additional X-Y storage oscilloscopes.     

Water desalination across nanoporous graphene

We show that nanometer-scale pores in single-layer freestanding graphene can effectively filter NaCl salt from water. Using classical molecular dynamics, we report the desalination performance of such membranes as a function of pore size, chemical functionalization, and applied pressure. Our results indicate that the membrane's ability to prevent the salt passage depends critically on pore diameter with adequately sized pores allowing for water flow while blocking ions. Further, an investigation into the role of chemical functional groups bonded to the edges of graphene pores suggests that commonly occurring hydroxyl groups can roughly double the water flux thanks to their hydrophilic character. The increase in water flux comes at the expense of less consistent salt rejection performance, which we attribute to the ability of hydroxyl functional groups to substitute for water molecules in the hydration shell of the ions. Overall, our results indicate that the water permeability of this material is several orders of magnitude higher than conventional reverse osmosis membranes, and that nanoporous graphene may have a valuable role to play for water purification.     

Nanostructured materials for water desalination

Desalination of seawater and brackish water is becoming an increasingly important means to address the scarcity of fresh water resources in the world. Decreasing the energy requirements and infrastructure costs of existing desalination technologies remains a challenge. By enabling the manipulation of matter and control of transport at nanometer length scales, the emergence of nanotechnology offers new opportunities to advance water desalination technologies. This review focuses on nanostructured materials that are directly involved in the separation of water from salt as opposed to mitigating issues such as fouling. We discuss separation mechanisms and novel transport phenomena in materials including zeolites, carbon nanotubes, and graphene with potential applications to reverse osmosis, capacitive deionization, and multi-stage flash, among others. Such nanostructured materials can potentially enable the development of next-generation desalination systems with increased efficiency and capacity.