PREDICTION OF PSYCHROMETRIC PARAMETERS USING NEURAL NETWORKS

Abstract

A neural network approach was used for the prediction of the psychrometric parameters in a non-iterative manner. Neural network models were developed for the each of the three main variables - dry bulb temperature, wet-bulb temperature and relative humidity - as a function of the other two variables. Models were also developed for the prediction of the dew point temperature using the dry bulb and wet bulb temperatures, and for the saturation vapor pressure as a function of the dry bulb temperature. The sensitivity of the neural network performance to the form of input and output variables employed was also investigated. The prediction accuracy of the neural network models were found to be very good, with errors less than 4%.     

某电子厂房洁净空调加湿方式的选择

以某电子厂房净化空调设计加湿方式的选择为例,分析了三种加湿方案的选择过程及使用条件,确定本工程最佳加湿方案。     

直接空冷机组空冷单元内喷雾方向对增湿效果影响的数值研究

以北方某600 MW直接空冷机组空冷单元内的喷雾增湿系统为例,在综合两相流、传热传质理论并结合实际运行过程的基础上,建立具有实用意义的喷雾增湿三维数学模型。利用计算流体力学（computational fluid dynamics,CFD）软件模拟出当喷雾系统喷雾方向发生变化时的空气流场和雾滴流场,分析出喷雾方向对喷雾增湿效果的影响,且找出最有利的喷雾方向,为直接空冷系统空冷单元内增加喷雾增湿系统提供参考。     

谈“控制增湿+强夯法”处理湿陷性粉土地基

结合工程实倒,介绍了"控制增湿+强夯法"在湿陷性粉土地基中的应用,从处理方法、检测等方面进行了阐述,指出强夯法可以有效消除土层的湿陷性、增强地基土的密实度、降低土层的压缩性、提高地基的承载力。     

Solarthermal seawater desalination systems for decentralised use

The performance of a pilot solar Multi Effect Humidification (MEH) Desalination system in Fuerteventura, Canary Islands, had been measured and analysed in detail by the ZAE Bayern since 1992. The investigated distillation units showed constant performance over several years without extensive maintanance. However the efforts towards further efficiency improvement by economic means pointed out the need of supplementing the system with a thermal storage tank. The distillation unit being the most expensive part of a desalination system has to be run 24 hours a day in order to be economic. A cost estimation for storage implementation yields the result, that cost reduction for the produced water by more than a half is possible. In April 1997 a desalination system with 24 hour thermal storage was built up in Sfax / Tunisia. The results of a short term measuring campaign at this site are presented here.For optimizing the ratio of sizes of thermal storage, collector field and distillation module a simulation tool for collector field and storage is developed at the ZAE Bayern. The simulation results of a combined laboratory distillation unit and storage system are presented.     

复合增湿方式下CFB-FGD塔内液-固相浓度分布及其对脱硫过程的影响

为解决循环流化床烟气脱硫(circulating fluid bed-flue gas desulfurization,CFB-FGD)工艺常用的塔内喷粉增湿方式存在的问题,提出新型复合增湿方式,采用粒子动态分析仪(particle dynamics analyzer,PDA)与傅里叶变换红外分析仪(fourier transform infrared spectroscopy,FTIR),对复合增湿不同配比下液-固相浓度分布之间相对关系的变化,以及该变化对脱硫反应过程、黏壁问题的影响进行研究,并与单一塔内增湿方式进行对比.结果表明:CFB-FGD单一塔内增湿方式下液-固两相的浓度分布趋同性较差,易形成过湿颗粒引起黏壁:采用复合增湿能有效提高液-固两相的浓度分布趋同性,有利于改善塔内黏壁问题,但内增湿水量过低不利于脱硫反应高效进行;内增湿水占总增湿水量的比例为78%时比较合适,在此配比下能够有效减轻塔内黏壁并提高脱硫效率.     

压力雾化喷嘴在受限空间气流中喷雾特性的实验研究

对出口直径为0.21、0.28、0.38、0.46mm的4种压力雾化喷嘴及其组合在150mm×150mm×1 000mm的矩形通道中的喷雾流场进行了实验研究,矩形通道中的空气流速为10m/s。研究了喷嘴布置和组合方式对雾化流场的影响。实验结果表明:喷雾不碰壁距离随入射角的增大而增大;顺流喷雾比无气流时液滴的平均D32减小10%,粒径范围略有扩大;逆流喷雾比无气流时液滴的平均D32增大约70μm,粒径范围扩大了3⁴倍;出口直径小的喷嘴可通过逆流布置和顺流布置的组合,获得液滴粒径分布范围更宽的气液两相流场。双喷嘴在有限空间内的雾化效果与流场中气液流量比有关。所得研究结论对天然气加湿技术的开发有一定参考价值。     

云冈热电直接空冷喷湿系统研究与应用

夏季高温时,直接空冷机组的出力受阻是较普遍的问题。采用喷雾增湿法可有效降低空冷器入口处的空气温度,改善空冷器的换热效果,提高机组运行的真空度并使其满发。为了研究雾化增湿降温法在直接空冷机组中应用的可行性和有效性,采用CFD技术对雾化增湿系统进行了三维数值模拟,并进行了现场试验。通过数值模拟研究和试验分析,在直接空冷系统中采用喷雾增湿法是可行的,增设喷雾增湿系统后,不仅可以显著提高机组的经济性,而且有利于机组的安全运行,具有较高的应用价值。     

Proton exchange membrane fuel cell system diagnosis based on the signed directed graph method

The fuel-cell powered bus is becoming the favored choice for electric vehicles because of its extended driving range, zero emissions, and high energy conversion efficiency when compared with battery-operated electric vehicles. In China, a demonstration program for the fuel cell bus fleet operated at the Beijing Olympics in 2008 and the Shanghai Expo in 2010. It is necessary to develop comprehensive proton exchange membrane fuel cell (PEMFC) diagnostic tools to increase the reliability of these systems. It is especially critical for fuel-cell city buses serving large numbers of passengers using public transportation. This paper presents a diagnostic analysis and implementation study based on the signed directed graph (SDG) method for the fuel-cell system. This diagnostic system was successfully implemented in the fuel-cell bus fleet at the Shanghai Expo in 2010.     

Technologies for increasing CO2 concentration in exhaust gas from natural gas-fired power production with post-combustion, amine-based CO2 capture

Enhanced CO₂ concentration in exhaust gas is regarded as a potentially effective method to reduce the high electrical efficiency penalty caused by CO₂ chemical absorption in post-combustion capture systems. The present work evaluates the effect of increasing CO₂ concentration in the exhaust gas of gas turbine based power plant by four different methods: exhaust gas recirculation (EGR), humidification (EvGT), supplementary firing (SFC) and external firing (EFC). Efforts have been focused on the impacts on cycle efficiency, combustion, gas turbine components, and cost. The results show that the combined cycle with EGR has the capability to change the molar fraction of CO₂ with the largest range, from 3.8 mol% to at least 10 mol%, and with the highest electrical efficiency. The EvGT cycle has relatively low additional cost impact as it does not require any bottoming cycle. The externally fired method was found to have the minimum impacts on both combustion and turbomachinery.