发动机怠速控制的研究

为了更好的控制怠速空气流量,以保持发动机的怠速稳定性,本文根据步进电机式怠速控制阀的工作原理设计了步进电机的驱动电路,并使用基于DSP的已集成该驱动电路的控制电路板对怠速阀进行控制.分析了发动机怠速系统的控制模型,同时讨论了怠速控制方法.实验研究了怠速空气流量与步进电机位置的关系,由此可以通过怠速空气流量的计算值计算出步进电机应处的位置.     

房间空调系统的优化控制模拟分析

针对一个实际的房间空调系统,考虑了外界气候条件的变化因素的影响,模拟了冷冻水常规定流量模式下系统的动态特性,分析了其控制精度不高的原因.在此基础上,用变流量的方法对冷冻水系统进行控制,比较了常规的PID控制和模糊自适应PI控制两种控制方法的优劣.模拟结果表明,模糊自适应PI控制超调量更小,响应时间更快.     

自力式流量控制阀在某研究院热网系统中的应用

针对某研究院供热系统中存在的水力失调问题,提出了采用自力式流量控制阀作为供热系统的流量调节控制设备的技术方案.经过一个供暖期的使用标明,近端热源户的流量和阻力减小,远端用户有了压差,循环大为改善,系统水力失调问题基本解决,供热趋于合理,降低了电耗.仅循环泵用电就节约了十几万元,效益显著.     

发动机怠速控制的研究

为了更好地控制怠速空气流量,以保持发动机的怠速稳定性,根据步进电机式怠速控制阀的工作原理设计了步进电机的驱动电路,并使用基于数字信号处理器(DSP)的已集成该驱动电路的控制电路板对怠速阀进行控制。分析了发动机怠速系统的控制模型,同时讨论了怠速控制方法。实验研究了怠速空气流量与步进电机位置的关系,由此可以通过怠速空气流量的计算值计算出步进电机应处的位置。     

先进压缩空气储能系统模拟与效率分析

为了解决温度变化对压缩空气储能系统中设备材料和系统效率的影响,提出了一种通过调节空气质量流量来控制温度变化的方法,利用Aspen Plus Dynamics软件建立系统模型,研究进气温度和流量比对系统效率的影响.结果 表明:相比定压比方式,在变压比下系统效率更高;进气温度对系统效率的影响不明显;流量比相同时,系统效率变化范围较小;保持工质质量流量一定,降低进气质量流量可提高系统效率.     

东深供水工程泵站加减流量时间点的控制策略研究

结合东深供水工程控制运用策略,研究了系统进入稳态运行前流量平衡时加减流量的时间点的确定方法,为控制策略的制定提供了一种快速有效的途径.     

简析中央空调系统节能的控制方法与发展趋势——基于江中药业综合制剂大楼中央空调节能改造工程案例

基于江中药业综合制剂大楼中央空调节能改造工程案例,以工程改造的节能技术措施和效果为分析对象,从系统节能的控制方法的角度对中央空调系统节能的发展转变进行剖析。通过调查和数据收集,对目前常用的2种中央空调系统(定流量控制型、变频PID控制型)节能方法的优缺点做了比较分析,展示了各种中央空调系统节能发展转变的特色,提出了中央空调系统节能发展方式、实现高效节能的建议。     

定燃料流量和定燃料利用率时SOFC发电系统特性研究

在定燃料输入流量和定燃料利用率两种典型控制方式下,建立了固体氧化物燃料电池(SOFC)发电系统模型.研究了两种控制方式下的固体氧化物燃料电池堆的稳态特性,采用定燃料流量控制方式时考虑了燃料流量对SOFC稳态特性的影响.针对出现负荷改变和故障的情况,分别在两种典型控制模式下对SOFC发电系统进行了仿真,通过对仿真结果的比...     

高压泵流量控制装置中电磁阀的优化设计

介绍了一种新型的用于柴油机共轨系统的高压泵流量控制装置.应用Ansoft公司的电磁场分析软件Maxwell 2D,对流量控制装置中电磁阀电磁作用力进行二维有限元分析,讨论了电磁阀在不同的线圈窗口尺寸及位置、材料及衔铁厚度下电磁力的大小,实现了结构的优化设计.试验结果表明:优化设计后的电磁阀能满足流量控制的需要,流量控制装置能将共轨压力波动控制在5%范围内.     

DCS基础控制方法改进的探讨

指出目前大量应用的DCS因存在的问题而影响了使用效果。说明了基础控制部分实现闭环稳定控制的重要意义。介绍了无模型控制方法及其在大庆石化公司化工二厂丁辛醇装置羰基合成反应器丙烯流量控制中实现闭环稳定控制成功的实例,并提出把现有DCS改造成基于无模型控制方法的DCS的建议,分析了改造的必要性和可能性。     

火电厂节能工作浅析

本文探讨了火电厂节能基本程序和工作方法,分析节能工作要从基础工作、技术创新、设备整治、燃烧管理等方面入手的论述.     

浅析磨合期汽车的使用

如何合理使用磨合期的汽车，使其摩擦机件的磨损量能够平稳、均匀地磨合而不至于过度磨损，对汽车实际使用寿命有着重要的意义。从机器磨合期的特点和磨损机理出发，对汽车磨合期如何正确使用进行了有实际意义的探讨。     

Geothermal energy in agriculture in Yugoslavia

SFR Yugoslavia has natural hot water springs practically all over its territory, indicating the presence of geothermal reservoirs underground. There is no final estimate of how much energy can be expected from this new resource, except for figures based on the results of studies and investigations.The first use of geothermal energy in Yugoslavia in numerous spas dates back to the 19th century. Some remarkable examples of central heating are known, but the most widespread use is in agriculture (in greenhouse heating, farm heating and drying of agricultural products).     

Energy conservation measures in an institutional building in sub-tropical climate in Australia

In this study, various energy conservation measures (ECMs) on heating, ventilating and air conditioning (HVAC) and lighting systems for a four-storied institutional building in sub-tropical (hot and humid climate) Queensland, Australia are evaluated using the simulation software called DesignBuilder (DB). Base case scenario of energy consumption profiles of existing systems are analysed and simulated first then, the simulated results are verified by on-site measured data. Three categories of ECMs, namely major investment ECMs (variable air volume (VAV) systems against constant air volume (CAV); and low coefficient of performance (COP) chillers against high COP chillers); minor investment ECMs (photo electric dimming control system against general lighting, and double glazed low emittance windows against single-glazed windows) and zero investment ECMs (reset heating and cooling set point temperatures) are evaluated. It is found that the building considered in this study can save up to 41.87% energy without compromising occupancies thermal comfort by implementing the above mentioned ECMs into the existing system.     

Uncertainties in decarbonising heat in the UK

Heating is arguably one of the most difficult sectors to decarbonise in the UK's energy system. Meeting the 80% greenhouse gas emission reduction target by 2050 is likely to require that heat related emissions of CO₂ from buildings are near zero by 2050, and there is a 70% reduction in emissions from industry (from 1990 levels). Though it is clear that the use of the natural gas network will reduce over time, recent modelling suggests a limited residual role for gas by 2050 to help meet peaks in heat demand. High levels of uncertainty about the way in which heat will be decarbonised present a number of challenges to policy makers. This paper will explore the risks and uncertainties associated with the transition to a low carbon heat system in the UK as outlined by the 4th carbon budget review. The potential impact of key uncertainties on the levelised costs of heat technologies and the development of energy networks are explored using a sensitivity analysis approach. Policy changes required to decarbonise the heat sector are also examined.     

Solar drying in sludge management in Turkey

Two main wastewater treatment plants in Bursa city in Turkey will start to operate and produce at least 27,000 tons of dry solids per year by the end of 2006. The purpose of this study was to investigate an economical solution to the sludge management problem that Bursa city would encounter. The general trend in Turkey is mechanical dewatering to obtain a dry solid (DS) content of 20%, and liming the mechanically dewatered sludge to reach the legal landfilling requirement, 35% DS content. This study recommends limited liming & solar drying as an alternative to only-liming the mechanically dewatered sludge. Open and covered solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. Faecal coliform reduction was also monitored. The specially designed covered solar drying plant proved to be more efficient than the open plant in terms of drying and faecal coliform reduction. It was found that, if the limited liming & solar drying method was applied after mechanical dewatering instead of only-liming method, the total amount of the sludge to be disposed would be reduced by approximately 40%. This would lead to a reduction in the transportation, handling, and landfilling costs. The covered drying system would amortize itself in 4 years.     

Viscous heating in liquid flows in micro-channels

Many experimental works on forced convection through micro-channels evidenced that when the hydraulic diameter is less than 1 mm, conventional theory can no longer be considered as suitable to predict the pressure drop and convective heat transfer coefficients. This conclusion seemed valid for both gas and liquid flows. Sometimes the authors justified this claim by invoking “new” micro-effects. On the contrary, in this paper the explanation of the experimental results obtained for micro-channels in terms of friction factors will be researched inside the conventional theory (Navier-Stokes equations). In particular, this paper will focus on the role of viscous heating in fluids flowing through micro-channels. A criterion will be presented to draw the limit of significance for viscous dissipation effects in micro-channel flows. The role of the cross-sectional geometry on viscous dissipation will be highlighted and the minimum Reynolds number for which viscous dissipation effects can no longer be neglected will be calculated as a function of the hydraulic diameter and of the micro-channel geometry for different fluids. It will be demonstrated how viscous effects can explain some experimental results on the Poiseuille numbers in micro-channels, which recently appeared in the open literature.     

Electoral cycles in electricity losses in India

A third of electricity in India is lost each year, where losses refer to power that is supplied but not billed. Utilizing data from the power corporation of Uttar Pradesh, India's most populous state, we study the politics of electricity losses. Examining annual data over four decades, we document that UP's electricity losses tend to increase in periods immediately prior to state assembly elections. Drawing upon geographically disaggregated data for the period 2000–09, we observe higher line losses just prior to the 2002 and 2007 state elections. Our analysis shows that the incumbent party was more likely to retain the assembly seat as line losses in the locality increased. We interpret these results as corroboration that political parties deliberately redirect electricity to flat rate and unbilled users in a context of chronically inadequate supply. Political factors appear to affect line losses in ways that technical and economic factors alone cannot explain.     

Energy consumption in rural transportation in India

Energy consumption in rural transportation has been computed, taking into account the energy embodied in vehicles or bullocks, as well as the fuels or feeds and food (of operators). Bullock cart transport consumes over four times more energy than vehicles. However, animal transport will continue to be preferred because of its availability.