基于谐波小波变换的4_73风机压力侧失速特性分析

在对离心风机压力侧失速的形成机理定性分析的基础上,通过对4-73风机的实验研究,发现4-73风机存在压力侧失速现象,并采用谐波小波变换对于压力侧失速的时频特性进行了分析。在分析中,对于时域定位能力较差的正交谐波小波进行频域光滑处理,在旋转失速的分析中引入非正交谐波小波变换,分析结果证明了谐波小波变换对于离心风机旋转失速特性分析的有效性。     

多翼离心式风机内部三维流场数值模拟与分析

利用FLUENT软件,以三维时均N-S方程和标准两方程湍流模型为基础,采用SIMPLE算法,对离心式通风机内部整机流场进行了三维数值模拟并分析了其内部流动特征。数值模拟结果显示,离心式通风机内部流场存在着明显的不对称性,各个叶轮流道的压力和速度分布并不相同。最后利用五孔探针流场测试系统试验台,使用MGS通风机实验数据采集系统和数据处理系统实验验证模拟流场的准确性,并通过改变风机的出口尺寸,对整体风机的性能分析,为离心式通风机的优化设计提供了依据。     

电站离心式风机性能在线监测的研究及其在DCS中的实现

针对风机设计，运行和性能特点，分析了进行电站风机性能监测重要性和必要性，建立了以曲面拟合理论和神经网络拟合为基础的离心式风机性能监测模型，并与DCS结合完成了通风机性能监测，最后通过现场实践进行了验证。     

太阳能集热器的能质分析

依据热力学第一、二定律，对平板型太阳能集热器的传热和流动过程进行了能质综合分析，提出了一项评价太阳能集热器热力学性能的指标——单位有用收益的Yong损，讨论了雷诺数、无因次入口换热温差和无因次热流密度等参数对太阳能集热器热力学性能的影响。     

入口脉动对太阳能空气集热器性能影响研究

提出将脉动流引入平板型太阳能空气集热器,通过增加壁面切应力延缓集热器内部积灰速率,提升其长期工作性能。采用数值模拟手段评估了集热器内部积灰对集热性能的影响,探讨了入口正弦型脉动流脉动参数对集热器流动和传热特性的影响。结果表明:在脉动周期内,集热效率基本不随时间变化,除了在0.5～2 Hz小范围低频脉动工况,集热效率均没有超过稳态流动时的集热效率,并且随着无因次振幅和脉动频率的增大,集热效率呈下降趋势;全压损失只随无因次振幅的增大而增加,当无因次振幅增大到1时,全压损失约增加40%左右;平均壁面切应力随无因次振幅和脉动频率的增大而显著增大,当无因次振幅为1,脉动频率为10 Hz时,平均壁面切应力较稳态时可增大132.4%,这将有利于延缓积灰速率并减小积灰厚度,对集热器长期工作性能提升起到积极作用。     

基于参数自适应FastICA的风电场谐波发射水平评估

风机滤波器及无功补偿设备可能导致风电场侧的谐波阻抗并非远大于系统侧谐波阻抗,因此在评估谐波发射水平时,不能忽略风电场侧阻抗的影响。基于此,提出一种基于参数自适应FastICA的系统侧谐波阻抗估计方法。根据PCC点两侧谐波源波动量的独立性,利用参数自适应FastICA方法提取独立分量,采用最小二乘法求解混合矩阵,进而求得系统侧谐波阻抗。通过风电场元件参数,计算风电场侧谐波阻抗的近似值,并考虑风电场侧谐波阻抗的影响,评估谐波发射水平。仿真及实测分析验证了此方法的有效性。研究成果可为类似风电场谐波发射水平的评估提供参考。     

矿井主通风机的节能运行

一、前言 据笔者调查,矿井主通风机的电耗损失约占我局总电耗的26％。所以,努力节约主通风机用电,对降低吨煤成本,提高企业经济效益有着重大的意义。 欲降低主通风机的能耗,关键在于如何采取措施,以提高主通风机的运行综合效率,实现节能的目的。 二、及时了解掌握主通风机性能,合理使用主通风机 在通风设计时,主通风机的选用往往是依据出厂时所提供的个体特性曲线来确定的,然而,由于制造和安装质量的不同,风机的实际运行性能与出厂时所标定的性能存在着较大的差异。另外,由于风机受长期运转所磨损、检修质量、锈蚀等因素的影响,其性能也会发生很大的变化。所以及时了解和掌握风机的实际性能,对合理、有效地使用风机至关重要。及时地对通风机进行鉴定,是了解掌握主通风机在实际运行状态下的性能的唯一方法。在日常管理中,我们对此非常重视,常根据我局风机的运行情况,给予适时的鉴定,并依据所鉴定的结果,采取必要的措施。譬如,我们在1992、1989年分别对翠屏山矿+450风井的9—57—No12B离心式风机和红一矿+473风井的4—72—11No12B离心式风机进行性     

出口结构变化对微型轴流风机气动性能影响的研究

以某低压微型轴流风机为研究对象,采用数值计算与风洞试验相结合的方法,研究出口支撑架的结构参数对微型风机气动性能和内部流动特性的影响。结果表明:椭圆形支撑架较之方形和圆柱形支架,其尾迹区内气流流动明显更加均匀,能量损失较小;对于?4×3、?4×4和?3×4,3种规格支撑架,支撑架的数量最少,且支撑架所占出风口截面面积最小的?4×3支撑架,对微型风机模型的性能影响最小。     

浅析涡轮机稳定性的成因 预防措施及对能耗的影响

涡轮机(砂水泵,风机)总是和网路联合起来工作的,工作介质为流体,但流体通过涡轮机时获得能量,其P—Q曲线按涡轮机的压力特征性能曲线变化,而流体通过网路时释放其能量,其P—Q曲线按网路阻力特征性能曲线变化。所以涡轮机的工作点(工况点)是由涡轮机的压力特征性能曲线与网路阻力特征性能曲线的交点决定的,并且只有一个唯一的交点,才是涡轮机的工作点。     

通风机叶片的仿生学试验研究

介绍了通风机仿生学叶片对通风机性能、噪声影响的试验研究初步结果,表明仿生学在风机中应用的尝试是有益的。     

新型管板式太阳能PV/T集热器光热特性研究与优化

为提高太阳能光伏/光热（PV/T）集热器全年运行效率,提出一种新型管板式太阳能PV/T集热器结构,并针对该集热器光热传递与光电转换过程进行分析,建立水和空气同时运行时的二维非稳态传热数学模型;在验证模型可靠性的基础上,模拟研究空气流道高度和空气流量等设计参数对PV/T集热器光热、光电特性的影响。结果表明,空气流道高度为15 mm时,PV/T集热器光电光热综合性能效率最佳;在所研究的工况下,该集热器的光电光热综合性能效率为0.84~0.87。     

鼓风机变频调速技术与节能

介绍了煤气鼓风机变频调速技术的原理和特点，通过煤气鼓风机变频调速技术改造的实践和鼓风机几种节流调节方式的对比，说明了变频调速技术的节能特性及效果，减少操作强度，节能效果显著。     

Exergetic performance evaluation and parametric studies of solar air heater

The present study aims to establish the optimal performance parameters for the maximum exergy delivery during the collection of solar energy in a flat-plate solar air heater. The procedure to determine optimum aspect ratio (length to width ratio of the absorber plate) and optimum duct depth (the distance between the absorber and the bottom plates) for maximum exergy delivery has been developed. It is known that heat energy gain and blower work increase monotonically with mass flow rate, while the temperature of air decreases; therefore, it is desirable to incorporate the quality of heat energy collected and the blower work. First it is proved analytically that the optimum exergy output, neglecting blower work, and the corresponding mass flow rate depend on the inlet temperature of air. The energy and exergy output rates of the solar air heater were evaluated for various values of collector aspect ratio (AR) of the collector, mass flow rate per unit area of the collector plate (G) and solar air heater duct depth (H). Results have been presented to discuss the effects of G, AR and H on the energy and exergy output rates of the solar air heater. The energy output rate increases with G and AR, and decreases with H and the inlet temperature of air. The exergy-based evaluation criterion shows that performance is not a monotonically increasing function of G and AR, and a decreasing function of H and inlet temperature of air. Based on the exergy output rate, it is found that there must be an optimum inlet temperature of air and a corresponding optimum G for any value of AR and H. For values of G lesser than optimal corresponding to inlet temperature of air equals to ambient, higher exergy output rate is achieved for the low value of duct depth and high AR in the range of parameters investigated. If G is high, for an application requiring less temperature increase, then either low AR or high H would give higher exergy output rate.     

钻井平台温控风机研制及节能评价

根据目前钻井平台风机运行中存在的能源浪费的现状,提出了在保障安全前提下的风机温控方案,并开展设备研制,在钻井平台上成功应用。对温控风机系统的能耗监测表明该系统起到了预期的节能效果,为钻井平台技术节能提供了实施案例。     

Exergy transfer characteristics of forced convective heat transfer through a duct with constant wall temperature

The exergy transfer characteristics of fluid flow and heat transfer inside a circular duct under fully developed laminar and turbulent forced convection are presented. Temperature is kept constant at the duct wall. The exergy transfer Nusselt number is put forward and the analytical expressions for exergy transfer Nusselt number are obtained as functions of heat transfer Nusselt number, Reynolds number, Prandtl number, etc. The variations of the local and mean convective exergy transfer coefficient, non-dimensional exergy flux, exergy transfer rate, etc. with operating parameters are presented graphically. By reference to a smooth duct and taking air as working fluid, a numerical analysis of the influence of the Reynolds number and non-dimensional cross-sectional position on exergy transfer characteristics has been conducted. The results show that the process parameters and configuration in the fluid flow and heat transfer inside a duct should be properly selected so that the forced convection process could have the best exergy utilization. In addition, the results corresponding to the exergy transfer and energy transfer are compared.     

Second law analysis of a waste heat recovery steam generator

In recent years a great deal of attention is focussed on the efficient utilization of energy resources with minimum heat loss. There is a growing interest on second law analysis to minimize the entropy generation in various thermal units and thereby to improve and optimize the design and performance. In the present work, a waste heat recovery steam generator is considered, which consists of an economizer, an evaporator and a super heater. The unit produces superheated steam by absorbing heat from the hot flue gases. A general equation for the entropy generation has been proposed, which incorporates all the irreversibilities associated with the process. By using suitable non-dimensional operating parameters, an equation for entropy generation number is derived. The effect of various non-dimensional operating parameters, on the entropy generation number are investigated. The role of gas specific heat, non-dimensional inlet gas temperature difference ratio (τ), heat exchanger unit sizes (NTUB, NTUS, NTUE) on entropy generation number are also reported. The results will help to understand the influence of different non-dimensional operating parameters on entropy generation number, which in turn will be useful to optimize the performance of the unit.     

某330 MW机组送风机喘振跳闸分析

为解决某330 MW机组配置的FAF22.4-12.5-1型动叶可调轴流式送风机喘振跳闸问题,对机组历史运行数据、风道阻力及风机出力进行分析。结果表明,送风机喘振的直接原因是,炉膛压力偏高及二次风箱压差偏大导致高负荷时送风机出口风道阻力增大。提出了有效预防送风机喘振的措施,包括运行过程中控制两侧送风机运行参数在合理范围、保持炉膛压力调整为微负压状态和同时保持二次风箱压差控制在规定值内,有效解决了运行过程中送风机喘振问题。     

DF4B(C)型机车热风机电机的改造

简述了DF4B(C)型机车热风机电机目前存在的主要弊端和开发热风机新型直流无刷电机的过程;介绍了新型电机的性能、参数、工作原理和实际运用情况。     

螺纹槽管错排管束的传热特性及流动阻力特性研究

1引言近年来,随着市场经济的发展,换热设备迫切需要节约能源、节省材料和降低成本的优化设计,因此强化传热技术受到了国内外的广泛重视。螺纹槽管是一种有效的强化换热管型,由于螺纹槽管的粗糙表面,可以有效地防止烟气在管内积灰而造成换热能力的下降,可以提高壁温以避免低温腐     

On the role of inserts in forced convection heat transfer augmentation

The role of inserts in internal forced convection has been widely acknowledged as a passive device in the heat transfer enhancement. The present study is aimed to empirically investigate the heat transfer enhancement in a tube fitted with a square-cut circular ring insert in the transitional and the fully turbulent flow regimes. By performing an in-depth analysis on the experimental data, the role of insert has been quantified by deriving a new non-dimensional group. This new non-dimensional group is proposed to characterize the effect of inserts on the heat transfer enhancement. While the findings show the incorporation of insert in the flow passage enhances the heat transfer rate, the characteristics of the flow in the transitional and the fully turbulent flow regimes induced by the effect of insert are distinct. The new non-dimensional group provides interesting insights into the role played by the insert. The physical significance of the non-dimensional number which provides a measure of the change of enthalpy relative to the change of flow energy in the flow direction can be used to explain the decrease of heat transfer augmentation in the turbulent flow regime relative to the transitional flow regime. Based on the analysis of the non-dimensional group, it can be deduced that the contribution of the axial pressure drop in the heat transfer augmentation is marginal albeit not negligible compared to the temperature rise in the characterization of the heat transfer augmentation with the incorporation of insert. The evaluation of heat transfer augmentation efficiency based on the rate of change of internal energy shows that the performance efficiency of an insert would be identical in different flow regimes, contradictory to the widely held axiom that the effect induced by the insert on the heat transfer augmentation diminishes in the turbulent flow regime.