中部设风道的双炉排

中部设风道的双炉排是一种应用在层燃锅炉上的燃烧设备,这种中部设风道的双炉排不同于现有层燃锅炉使用的中部不设风道的双炉排。中部设风道的双炉排,可配套现有大型层燃锅炉使用。中部设风道的双炉排可使炉排宽度方向上的送风点数量增加,每个送风点的送风长度减小。可有效改善层燃锅炉因炉排过宽而造成的炉排布风延宽度不均匀,从而影响燃烧效果的问题。     

漆包机烘炉循环风道温度均匀性的仿真优化研究

为提高漆包机烘炉内循环风道横向温度均匀性以满足漆包线生产工艺要求,运用FLUENT软件对国内某厂生产的RHW3600漆包机循环风道内温度场、流场及压力场进行了数值模拟,分析了风道内温度不均匀及压力损失较大的主要原因,并对其结构型式进行优化设计。结果表明:分道模型有利于炉膛横向温度分布的均匀性;适当缩小匀风装置挡板尺寸可减少风道压力损失、提高炉膛两侧温度,但风道的横向温差略有增加;在匀风装置出口和分风道进口水平段加装导流挡板能有效提高炉膛横向温度分布的均匀性。本文提出的4种优化方案中,方案D模型最优,与实物模型相比,风道的横向最大温差降低了7 K,压力损失降低了4.7 Pa。     

多联机性能测试室温度场影响因素的实验研究

为了研究多联机性能测试室温度场的影响因素及解决其温度场不均匀性的问题,本文通过数值模拟和实验,研究了不同送风方式、不同送风速度和不同送风温度条件下测试室的温度场的温度变化情况。实验采用孔板顶送风、侧回风和四面风道送风、顶回风的送风形式;循环风机的转速设置30、40和50 Hz 3种;低温工况选取干球温度-20℃、,高温工况选取干球温度60℃,常温工况选取干球温度30℃。数值模拟结果与实验结果表明:相同送风温度和送风速度情况下,四面风道送风、顶回风的送风形式测试室温度场的均匀性较孔板顶送风、侧回风的送风方式温度均匀性差;相同送风方式和相同送风温度情况下,增大送风速度,相同位置处的温度随之降低,流场和温度场的分布趋势几乎不变;相同送风方式和相同送风速度情况下,送风温度越高,温度场越均匀。研究结果为多联机性能测试室的设计以及多联机性能的测试提供一定的理论和试验基础。     

隔断式工位空调系统气流组织与人体热舒适评价

采用K-ε湍流模型对采用隔断式工位空调的典型办公室工作微环境进行数值模拟,分析工位空调在人体周围所形成的非均一环境参数场,并进一步研究非均匀环境对人体热舒适的影响.在不同工位送风参数下对房间和人体周围环境参数的分布状况及吹风感和热舒适性进行研究.模拟结果发现:工位空调送风可以使室内温度呈现分区分布,工位送风效率高,可以...     

全生命周期城铁车辆空调系统节能技术分析

根据成熟项目的应用经验以及行业前沿技术,从全生命周期的角度阐述城铁车辆空调系统的节能关键技术。设计阶段城铁车辆可选择配置直流直进空调机组,进行K值理论计算优化整车隔热设计,优化座椅-侧墙回风方式的隔热措施,合理布置客室温度传感器以及应用变风量VAV控制系统,实现空调系统节能;阐述了运营阶段变新风技术和自动温控技术。提出维保阶段可配置PHM系统实现状态检修,保持机组健康状态,以及进行风道清洗提高整个空调系统能效比。     

地铁车厢送风参数对气流组织影响的研究现状

介绍了地铁车厢空调系统送风参数的选取原则和依据,综述了前人对地铁车厢空调系统送风参数的实测结果和气流组织的数值模拟结果,总结了送风参数对地铁车厢内气流组织的影响规律。结果表明,辐流风机有助于改善车厢内气流组织的均匀性;B型地铁载人情况下,当送风速度在1.5m/s左右时,车厢内速度场的均匀性较好;对于相同微风速环境下的A型地铁来说,满载车厢的空调送风速度高于空载车厢的送风速度,以上研究结果为提高地铁车厢的舒适性提供了理论基础。     

大空间两种气流组织夏季热环境及其能耗实验研究

以某大空间实验基地为研究对象,针对喷口送风和柱状下送风两种分层空调的热环境及供冷量进行了实测研究.研究结果表明:因喷口送风空调区较大,在夏季室外气象参数基本相同的两种室外气象条件下,喷口送风空调系统供冷量比柱状下送风空调系统的供冷量分别高出20.8%、24.4%,且喷口送风空调系统抗干扰能力较柱状下送风强;喷口送风时工作区温度均匀性好于柱状下送风,头足温差较小,但其工作区风速超过标准,而柱状下送风时工作区风速则符合环境设计要求;两种不同送风量下喷口送风时吹风感指数分别为15.64%、11.23%,而柱状下送风时吹风感指数分别为4.17%、2.40%,柱状下送风要明显优于喷口送风.故从节能及热舒适性角度综合考虑,单侧回风的大空间建筑应尽可能采用柱状下送风分层空调,而对于干扰比较大,空调场地较小,无法布置柱状下送风口的场合,则选取喷口送风较好.     

锅炉冷风道的流场仿真及道体结构优化研究

由于锅炉冷风道的道体结构设计不当,造成高能湍流脉动气体在风道内流速分布不均,产生大范围回流的漩涡扰动,导致道体振动。通过流场仿真研究,提出在风道内布置"井"字隔板装置,通过仿真研究,加装"井"字隔板后的风道内气体流速分布均匀程度得到较大改善,认为该方案如在实际工程中实施,可以较好地改善风道内气流分布均匀性和消除道体振动的问题。     

机车牵引电机通风机风道内部流动数值分析与结构改进

针对某动车组机车牵引电机通风机风道布风要求,利用Fluent软件,对通风道进行CFD数值仿真及优化分析。在满足机车复杂空间要求的前提下,确保风道3个出风口冷却风流量均匀,风阻小,并优化设计风道结构、内导流板和隔板布置。     

全空气定风量空调系统变频变风量运行控制与仿真研究

分析了全空气定风量空调系统空调房间的特性,推导出变风量送风方式下空调房间的数学模型,构造PID控制器、模糊控制器和神经网络控制器三种控制器,并利用Matlab软件中的Simulink工具箱对三种控制器的性能进行比较。     

新风量、送风方式和空调病症

本文叙述了新风量的大小和送风方式的不同与空调病症之间的关系。     

机车空压机不打风故障的分析处理

1　故障查找思路　　ＧＫ1Ｄ型液力传动内燃机车的空压机主电路示意图和空压机起动时的控制关系示意图如图 1和图 2所示。当出现空压机不打风的故障时 ,我们一般按这两幅控制关系示意图所示的线路 ,分析查找问题所在。其基本思路如下 :一是沿空压机起动控制线路查。查ＰＣ机、功放块、空压机起动接触器、保险。若都没问题 ,则查主电路。二是沿主电路查找 ,空压机的电机、电机接线盒内 (接线柱、接线片 )、电机绕组。2　故障的分析处理　　在实际检修过程中 ,具体可按如下步骤做 :( 1)看主电路中的空压机起动线路上的保险3ＲＤ、4ＲＤ是否烧…     

The effects of air leaks on solar air collector behaviour

The construction of conventinal solar air collectors and the fact that they will operate with a significant pressure difference between the heated air stream and ambient, suggests that significant quantities of air may leak into or out of them. A search of the literature reveals no consideration of the effects these air leaks may have on the validity of collector efficiency measurements, on the efficiency itself, or indeed what the meaning of efficiency is under such operating conditions. This paper discusses the meaning of collector efficiency when leaks into the collector occur, analyses the effects on efficiency measurements, and solves the collector efficiency for the simple case of a constant leakage rate along the collector. Assuming that air leaking in from ambient can replace deliberate fresh air supply to the load as in building heating, then significant measurement errors are made if air leaks in to the collector are not accounted for. Further, the collector efficiency is increased over the no leak case, so that complex construction methods to make the collector air tight are probably not warranted.     

Effect of air leak on long term performance of air heater

In this paper, the effect of an air leak on the air heater performance is investigated. “Air leaking in” and “air leaking out” systems are examined. The effect of various parameters like leakage rate, mass flow rate, solar insolation, plate length and ambient temperature has been studied. The possibility that air leakage can take place from any where along the length of the collector has been incorporated in the model. It is found that, for “air leaking in” systems, efficiency goes up, while for “air leaking out” systems, efficiency decreases from the no-leak situation, and it depends on the position of the leak.     

空气湿度对平板空气集热器效率的影响

对不同相对湿度下的湿空气密度、定压比热容、动力粘度和导热系数等热物性参数进行了计算。在给定的平板空气集热器模型下计算得出,工作介质为相对湿度50%的湿空气比工作介质为干空气的集热器效率高12.4%。文章研究分析了太阳辐射量、空气通道高度、入口空气流速及温度对平板空气集热器顶部损失系数和效率的影响,研究结果显示,它们对介质为干空气及介质为湿空气的集热器影响趋势一致。     

Analysis of exergy demand for air heating of an air handling unit

In modern buildings, an increasing amount of the consumed energy falls on ventilation systems. The amount of energy needed for ventilation depends on weather fluctuations, wind, interaction between natural gravity and air tightness of the building, heat exchangers used in ventilation systems, efficiency of other ventilation equipment, and operating mode of ventilation systems in the building. Ventilation systems are comprised of a variety of elements that facilitate processes using energy of different types. The main elements that use energy in ventilation systems are fans, heat exchangers, and heaters. They have a significant effect on both energy needs of a public building and the exergy efficiency of a system. In order to achieve a more efficient use of exergy in heat exchangers, it is recommended to execute processes under as little temperature difference as possible; however, this increases the area of heat exchangers. Results of the analysis show that it is recommended to design ventilation systems based on the temperature that corresponds with the maximum demand of exergy in order to use the heat recovery unit as much as possible in the system.     

空气调节二次回风系统的节能问题

讨论了二次回风系统在夏季工况下与一次回风系统相比的节能效果,以及在冬季工况如何更好降低能耗的问题,着重分析了冬季工况下机器露点对能耗的影响,并提出降低能耗的途径。     

地道风系统地埋管管径对出口空气温度的影响研究

构建了空气与地道壁面换热理论模型,用于计算地埋管出口空气温度,通过正交模拟分析了地埋管管径、长度以及进口风速对地埋管出口空气温度的影响,并与数值模拟结果进行对比.结果 表明:地埋管管径极差值最大,可达20.4 m,是地埋管出口空气温度的主要影响因素,地埋管长度和进口风速为次要因素;随着管径的增大,出口空气温度随之升高;...     

Thermoeconomic optimization of the geometry of an air conditioning precooling air reheater dehumidifier

Exergy method of optimization for the geometrical parameters of an air conditioning precooling air reheater with turbulent flow is developed in this paper. The method is based on exergy, economic analysis and optimization theory. As there are humid air streams involved in the heat transfer process, then there are irreversibilities or exergy destruction, which is due to pressure losses, temperature difference and specific humidity gradient. These principle components of total irreversibility are not independent and there is a trade‐off between them. Therefore, the purpose of this research paper is to study the effect of the geometry and the specific humidity of the two streams on the irreversibilities of a crossflow precooling air reheater dehumidifier. Also, the optimum balance between the three components of irreversibility is determined thereby giving the optimum solution for heat exchanger area. The total cost function is expressed on an annualized basis of the sum of the precooler capital cost and the running cost attributable to the precooler irreversibility. This total cost function is optimized in this paper according to the optimum heat transfer area and the total irreversibilities. Two optimum heat transfer areas were found for minimum total irreversibility and minimum total annual cost for a specific example. Finally, the relations between the typical operational variables such as heat transfer area, Reynolds numbers and the total annual cost for the precooler is developed and presented in graphs, which allow the calculation of the optimal heat transfer area, which gives the optimum irreversibility and minimum total annual cost. Copyright © 2005 John Wiley & Sons, Ltd.