基于Matlab的分级回热式增湿淡化过程模拟

针对太阳能海水淡化过程中回热效果差的问题,设计分级回热的空气增湿海水淡化装置,建立其数学模型,并利用Matlab进行仿真模拟。研究结果表明:该装置的最佳水气比为0.75,前置冷凝器最佳冷却水流量为空气量的1.0~1.5倍,该装置的回热效果提升了25%~30%,产水率为7.75 kg/(m2·d),淡化装置的整体热效率达到79.2%。     

跨临界CO2热泵系统性能研究

建立了跨临界CO_2热泵热水系统及其主要部件的数学模型并进行了模拟,利用自行搭建的跨临界CO_2热泵实验台进行了相关的实验研究。分析比较了气冷器的出口水温、气冷器的制热量与系统COP_h值(跨临界CO_2热泵系统)的仿真值与实验值,结果表明实验值与仿真值较为吻合,建立的系统模型准确性较高。利用仿真与实验的手段,研究了不同的冷却水流量和冷却水温度对跨临界CO_2热泵系统的性能影响。研究结果表明:系统运行时外部参数冷却水温度和流量及蒸发温度的变化将引起系统性能参数(制热量Q、系统COP_h值)变化,尤其是气冷器进口水温对系统性能的影响最大,为了保证气冷器中CO_2工质实现跨临界循环,降低气冷器进口水温是关键因素。     

ORC驱动RO海水淡化不同能量回收方式性能分析

建立了有机朗肯循环(ORC)驱动反渗透(RO)海水淡化复合系统计算模型,以混合工质R600a/R601a为有机工质,海水淡化所用海水经过冷凝器以提高淡水产量,并对使用不同能量回收装置的ORC-RO复合系统的性能进行比较。结果表明:BASIC系统、PWT能量回收系统和PES能量回收系统R600a/R601a的最佳混合比例分别为0.7/0.3、0.8/0.2和0.9/0.1;在渤海年平均水温12℃时,BASIC系统的最大淡水产量为5.04kg/s,采用PWT能量回收系统能使淡水产量提高38.69%,采用PES能量回收系统能使产水量提高130.36%;相同功耗下,3个系统比采用电驱动RO海水淡化的系统淡水产量分别提高80.96%、39.44%和19.57%;随着冷凝器进水温度的升高,PES系统的产水优势减弱,混合工质相比于纯工质的产水优势更加明显,可见复合系统的设计需要考虑冷凝器进水温度的影响。     

基于海洋温差能的海水淡化小试系统的建立及试验研究

介绍了利用海洋温差能进行海水淡化的基本原理,建立了设计规模为每小时淡水产量5 kg、模拟表层海水温度29 ℃、深层海水温度10 ℃的小试系统并进行了实验测试,得到了表层海水、深层海水流量与淡水产量的关系.实测结果表明,额定工况下最佳闪蒸温度为23.5 ℃,单位能耗为3.79 kWh.     

DME发动机起动怠速工况AMESim/Simulink联合仿真研究

以AMESim仿真软件中的发动机燃烧仿真平台IFP-Engine为基础,建立了发动机模型,利用MATLAB/Simulink软件的处理功能,建立了燃料供给系统控制模型,将二者联合仿真,结合实际发动机从起动到怠速转速的变化,调整参数,获得了发动机模拟转速变化规律,以此转速曲线确定某一时刻的基本喷油量,再根据冷却水温度对喷油量进行修正,绘制出转速、冷却水温、喷油持续时间等随时间的变化曲线,并分析发动机起动、怠速运转情况,为二甲醚(DME)发动机电控燃料供给系统控制器的研制提供了方法。     

常压开式循环太阳能海水淡化装置研究

提出一种开放式循环太阳能海水淡化系统,热力学效率和得水率是反映该系统能量利用程度及淡水产量和能耗关系的综合性指标,受加热、蒸发和冷凝三个环节制约,对诸多参数进行了分析,表明蒸发器入口海水温度和冷却水温度是影响系统性能的最重要两个参数,为改进系统性能和进行优化设计奠定了基础。     

用耦合法分析研究发动机的稳态传热

利用FLUENT分析软件对发动机的稳态传热进行了仿真模拟。以所建立的某柴油机耦合传热系统为例进行了仿真计算,得到了耦合系统(活塞、缸套、冷却水套)的温度场等相关信息。计算结果表明,用耦合法模拟柴油机活塞组、缸套和冷却水之间的稳态传热是可行的。     

基于风能利用的机械蒸汽压缩海水淡化系统模拟

通过对机械蒸汽压缩(mechanical vapor compression,MVC)-多效蒸馏(multi-effect evaporator,MEE)海水淡化系统建立模型,研究了压缩机输入功率与海水淡化系统运行参数之间的关系,分析了系统中压缩机与多效蒸发器之间相互耦合的匹配关系,探讨了辅助能源加热对系统运行状态及产水率的影响,并通过耦合风力发电机模型,研究了系统淡水产率随风电功率随机变化的响应曲线。结果表明:随压缩机输入功率的增加,多效蒸发器效间的传热温差增大,产水率也近似线性增加;辅助能源虽然有助于提高产水率,但其添加量不能超过一定的上限;对于一组平均为7.1m/s的随机风速,海水淡化系统的平均产水率为5.00t/h,平均产水能耗10.2kWh/t,而若采用20%辅助能源加热,可以使平均产水率提高0.21t/h。     

楼宇冷热电联供系统仿真及其影响制冷效果的分析

以上海交通大学某大楼的BCHP系统为研究对象,在ISEpro仿真平台上建立系统仿真模型,利用该模型对影响制冷效果的蒸汽压力、冷却水进口温度、冷媒水进口温度等因素进行了仿真分析,发现冷媒水进口温度、冷却水进口温度、工作蒸汽压力等因素对制冷效果影响较大,其结果和实际应用和理论计算相一致,表明该模型可以用来对楼宇冷热电系统进行仿真,并可为楼宇冷联供的设计、操作运行、控制调节提供指导.     

机械蒸汽再压缩式低温蒸发海水淡化蒸发性能实验研究

建立了一套机械蒸汽再压缩式低温蒸发海水淡化系统,以人工配制的盐水为对象,对机械蒸汽再压缩低温蒸发海水淡化系统进行实验研究,主要研究压缩机压缩比和蒸发温度对系统蒸发性能的影响。实验结果表明:产水率和压缩机比功耗随蒸发温度和压缩比的升高而升高,且压缩比对蒸发性能的影响较大。从节能及经济性角度上看,在满足产水要求和防结垢、防腐蚀需求下,选取较小的压缩比,和较大的蒸发温度有助于提高产水率,节约能耗。     

Artificial neural network analysis of liquid desiccant dehumidification system

The dehumidification process involves simultaneous heat and mass transfer and reliable transfer coefficients are required in order to analyze the system. This has been proved to be difficult and many assumptions are made to simplify the analysis. The present research proposes the use of ANN based model in order to simulate the relationship between inlet and outlet parameters of the dehumidifier. For the analysis, randomly packed dehumidifier with lithium chloride as the liquid desiccant is chosen. A multilayer ANN is used to investigate the performance of dehumidifier. For training ANN models, data is obtained from analytical equations. Eight parameters are used as inputs to the ANN, namely: air and desiccant flow rates, air and desiccant inlet temperatures, air inlet humidity, desiccant inlet concentration, dimensionless temperature ratio, and inlet temperature of the cooling water. The outputs of the ANN are the water condensation rate and the outlet desiccant concentration as well as its temperature. ANN predictions for these parameters are validated well with experimental values available in the literature with R² value in the range of 0.9251-0.9660. This study shows that liquid desiccant dehumidification system can be alternatively modeled using ANN with a reasonable degree of accuracy.     

海水淡化系统水平管降膜蒸发器传热系数研究

针对海水淡化系统水平管降膜蒸发器,总结和分析管内冷凝侧与管外蒸发侧的换热系数关联式,比较管内径、入口蒸汽流速、蒸汽冷凝温度、出口蒸汽干度对管内蒸汽冷凝侧换热系数的影响;研究传热温差以及喷淋密度对管外蒸发侧换热系数的影响。结合不同的污垢系数,进行了总传热系数的影响因素分析,为海水淡化系统的工程设计提供依据。     

基于水冷压缩式制冷循环的CO2水合物海水淡化实验研究

提出一种基于水冷压缩式制冷循环的CO₂水合物海水淡化方法,并进行了CO₂水合物海水淡化实验,实验选取4种不同的初始海水盐度（10‰、20‰、30‰、40‰）,控制其温度为20℃,在4种不同的充注压力（3.6 MPa、3.8 MPa、4.0 MPa、4.2 MPa）下进行实验,考察了初始海水盐度和充注压力对海水淡化效果的影响。结果表明,充注压力越高,初始海水盐度越低,水合反应预冷时间越短。在充注压力为4.2 MPa、初始海水盐度为10‰时,预冷时间最短（15.01 min）,淡化水产量最高（3 172.34 g）,淡化速率最快（211.35 g/min）,淡化水盐度最低（4.49‰）,盐去除率为5.11‰。在充注压力为4.2 MPa、初始海水盐度为30‰时,淡化水产量为2 868.66 g,淡化速率为165.63 g/min,淡化水盐度为6.49‰,盐去除率最高,为8.37‰。充注压力越高,初始海水盐度越低,则淡化水能耗越低。     

低温多效海水淡化工程材料的选用

通过对众和海水淡化工程有限公司参与设计并制造的三台低温多效海水淡化设备的研究,介绍了低温多效海水淡化工程用材料的选取,探讨了常用在低温多效海水淡化工程上的一些材料及其性能。在此基础上提出了对低温多效海水淡化工程材料选取的一些建议。     

低温多效蒸发海水淡化系统不同进料方式的热力学分析

应用Aspen Plus软件,建立了平流、顺流、逆流三种进料方式的低温多效蒸发海水淡化工艺流程,并进行了流程模拟,模拟结果与文献[6]进行了对比,验证了所建工艺流程的可靠性和流程模拟的准确性。在加热蒸汽质量流量和热力压缩机引射率相同的情况下,应用等温差分配法对三种进料方式海水淡化系统进行模拟计算,获得了造水比和比传热面积与蒸发器效数、浓缩比、效间温差和进料海水温度之间的关系。研究结果表明:蒸发器效数对系统的热力性能有显著影响,当效数较少时,采用平流进料方式较为合适;增大浓缩比可以提高造水比,且比传热面积变化不大;当浓缩比较大时,可采用顺流进料,以降低结垢风险;增大效间温差,会降低逆流进料方式的造水比,但会增加平流和顺流的造水比;提高进料海水温度可以提升系统热力性能,但进料海水温度受末效二次蒸汽温度的限制。     

Development of a steady‐state mathematical model for multistage flash (MSF) desalination plant

In this paper, a mathematical model for multistage flash (MSF) desalination plants was developed. The model was based on basic principles of physics and chemistry that describe the stages occurring in the desalination process. The input plant parameters that are known to affect the operation of the MSF desalination plant and its performance was taken into account in the construction of the model. These parameters included make‐up flow, brine recycle flow, seawater flow, seawater temperature, seawater concentration, top brine temperature (TBT), steam temperature and the plant load. For each stage, the developed model was used for predicting the temperatures of the brine, distillate and cooling brine, and the flow rates of brine outlet and distillate production. The developed model was evaluated with the MSF plant vendor simulation results and its actual operating data. The evaluation indicated that model predictions matched well with the vendor simulation results and the plant operating data. The developed model is sufficiently accurate and model predictions can be relied upon. Therefore, it may be recommended for determining optimum set point of a running MSF desalination plant at different loads to maximize the water production or minimize energy consumption. It can also be used to calculate controller set points for different loads of the plant. Copyright © 2011 John Wiley & Sons, Ltd.     

Solar field control for desalination plants

This paper presents the development and application of a feedback linearization control strategy for a solar collector field supplying process heat to a multi-effect seawater distillation plant. Since one objective is to use as much as possible the solar resource, control techniques can be used to produce the maximum heat process in the solar field. The main purpose of the controller presented in this paper is to manipulate the water flow rate to maintain an outlet–inlet temperature gradient in the collectors, thereby ensuring continuous process heating, or in other words, continuous production of fresh water in spite of disturbances. The dynamic behaviour of this solar field was approximated by a simplified lumped-parameters nonlinear model based on differential equations, validated with real data and used in the feedback linearization control design. Experimental results in the seawater desalination plant at the Plataforma Solar de Almería (Spain) show good agreement of the model and real data despite the approximations included. Moreover, by using feedback linearization control it is possible to track a constant gradient temperature reference in the solar field with good results.     

气隙扩散蒸馏海水淡化装置的㶲分析

利用海水淡化技术将淡水从海水中分离出来是解决淡水资源短缺问题的有效途径。气隙扩散蒸馏装置是一种热分离装置,该装置具有表面积大、工作温度低、热源适应性好、金属消耗量低、常压运行等优点,非常适合偏远山区和海岛地区的应用。对气隙扩散蒸馏模型进行了建模,利用NaCl水溶液模型进行了■分析。以热料液温度、冷料液温度、溶液流量对■效率的影响进行了敏感性分析。计算并比较了外热源、蒸发器、气隙和冷凝器的■损失。研究发现气隙扩散蒸馏装置■效率可以达到30%,为工艺优化和提高装置的能效提供了指导。     

Integration of thermal energy and seawater desalination

Energy and freshwater shortage are the bottlenecks restricting China's economic development. The integration of energy utilization system and seawater desalination is considered as an innovative technology enabling efficient simultaneous use of middle or low temperature thermal energy and supply freshwater. Three feasible approaches to integrate seawater desalination with energy utilization system are presented in this paper, including combinations of the desalination process with a Combined Cooling Heating & Power system (CCHP), a power plant, or a solar thermal utilization system. In addition, the feasibility and advantages of a seawater desalination system combined with a power plant are described. The findings indicate that combining seawater desalination with industrial processes is a feasible and promising way to solve the problems of the lack of freshwater and low efficient use of low temperature thermal energy in coastland areas.     

Experimental validation of the distillation module of a desalination station using the SMCEC principle

This paper presents the simulation and the experimental validation of the distillation module of a desalination unit, currently operating in Sfax, Tunisia. The desalination process is based on the Solar Multiple Condensation Evaporation Cycle (SMCEC) principle.The work presented in this paper focuses on modelling the desalination module as it is supplied with either water heated by solar energy or geothermal water. Geothermal water resources are abundant in Tunisia with salinity levels of 1–50 g/l. The simulation of the dynamic behaviour of the desalination module with and without disturbances on the inlet temperature was carried out to predict the variations of key output variables subjected to thermal variations. Such variables include water temperature, air temperature, humidity in the evaporation and condensation chambers and the amount of produced distilled water. To validate the dynamic model of the distillation module, a series of experiments was conducted. Experimental results were compared with the simulation results. It was shown that the developed model is able to predict accurately the trends of the heat and mass characteristics of the evaporation and condensation chambers. As a result, the proposed model can be used to design and test the behaviour of such a type of desalination unit.