Energy hub-based optimal planning for integrated energy systems considering part-load characteristics and synergistic effect of equipment

Integrated energy systems(lESs)represent a promising energy supply model within the energy internet.However,multi-energy flow coupling in the optimal configuration of IES results in a series of simplifications in the preliminary planning,affecting the cost,efficiency,and environmental performance of IES.A novel optimal planning method that considers the part-load characteristics and spatio-temporal synergistic effects of IES components is proposed to enable a rational design of the structure and size of IES.An extended energy hub model is introduced based on the“node of energy hub”concept by decomposing the IES into different types of energy equipment.Subsequently,a planning method is applied as a two-level optimization framework-the upper level is used to identify the type and size of the component,while the bottom level is used to optimize the operation strategy based on a typical day analysis method.The planning problem is solved using a two-stage evolutionary algorithm,combing the multiple-mutations adaptive genetic algorithm with an interior point optimization solver,to minimize the lifetime cost of the IES.Finally,the feasibility of the proposed planning method is demonstrated using a case study.The life cycle costs of the IES with and without consideration of the part-load characteristics of the components were$4.26 million and$4.15 million,respectively,in the case study.Moreover,ignoring the variation in component characteristics in the design stage resulted in an additional 11.57%expenditure due to an energy efficiency reduction under the off-design conditions.

Thermodynamic Performance Analysis of E/F/H-Class Gas Turbine Combined Cycle with Exhaust Gas Recirculation and Inlet/Variable Guide Vane Adjustment under Part-Load Conditions

Exhaust gas recirculation control(EGRC),an inlet air heating technology,can be utilized in combination with inlet/variable guide vane control(IGV/VGVC) and fuel flow control(FFC) to regulate the load,thereby effectively improving the part-load(i.e.,off-design) performance of the gas turbine combined cycle(GTCC).In this study,the E-,F-,and H-Class EGR-GTCC design and off-design system models were established and validated to perform a comparative analysis of the part-load performance under the EGR-IGV-FFC and conventional IGV-FFC strategies in the E/F/H-Class GTCC.Results show that EGR-IGV-FFC has considerable potential for the part-load performance enhancement and can show a higher combined cycle efficiency than IGV-FFC in the E-,F-,and H-Class GTCCs.However,the part-load performance improvement in the corresponding GTCC was weakened for the higher class of the gas turbine because of the narrower load range of EGR action and the deterioration of the gas turbine performance.Furthermore,EGR-IGV-FFC was inferior to IGV-FFC in improving the performance at loads below 50% for the H-Class GTCC.The results obtained in this paper could help guide the application of EGR-IGV-FFC to enhance the part-load performance of various classes of GTCC systems.

某商业建筑高效制冷机房运行数据分析

制冷机房作为系统工程,其系统运行参数的变化(如冷冻水供回水温差)会对机房内不同设备的能效产生不同的影响,机房整体能效最优是机房节能运行的重要目标。针对现有建筑运行数据存储较多但对其分析较少的现状,采用数据挖掘技术,对某商业建筑制冷机房实际运行能耗、能效进行统计计算,并将其与负荷率、供回水温度、供回水温差等变量的相关性展开分析,揭示机房能效与各变量间的内在联系。研究结果显示:制冷机房单位面积制冷能耗约为16~17 kW·h/(m^(2)·a),冷水机组能耗占80%以上,冷水机组的能效表现主导了机房的整体能效表现,机房系统能效比(COPs)高于设计值6.06 kW·h/kW·h,达到了预期目标。机房整体能效与室外气温及负荷率、冷冻(却)水供回水温差、冷却水进水出水温度呈负相关关系,机房整体能效与冷冻水供回水温度主要呈正相关关系。冷水机组运行COP与机组负荷率和冷却水回水温度呈现一定相关性,且基本符合机组定冷却水温和AHRI变冷却水温工况下的选型曲线。

冷水(热泵)机组能效测试方法及能效限定值的对比研究

冷水(热泵)机组作为集中空调系统的主要耗能设备,行业整体机组能效的提高会对按期实现“双碳”目标具有重大促进作用。GB/T 18430作为冷热水机组的基础性标准,修订工作已接近尾声,与之配套的能效标准GB19577—2015也需要进行相应的修订升级。对GB/T 18430中对舒适型冷水(热泵)机组的考核方法与对应美国和欧洲的进行了对比分析,构建了一个水冷式冷水(热泵)机组的理论模型,从而将中国、美国和欧洲能效标准中规定的限定值水平折算为同一个指标下进行对比。对比发现,我国目前水冷式机组的IPLV入门限定值分别提升5.4%和25.2%后可以达到美国能效标准A路径和B路径能效水平,提升13.4%后可与欧洲能效标准水平持平;风冷式机组能效限定值在数值上增加25.4%后可与欧洲能效标准基本持平。本文的工作为后续能效标准GB19577—2015的修订提供了参考依据。

基于固有应变法的中空薄壁铝合金结构件焊接变形及残余应力预测

为提升中空薄壁铝合金结构件焊接变形与残余应力预测精度。基于固有应变法与焊接热输入参数对焊接等效载荷开展求解,利用有限元仿真方式从变形及应力的角度出发,分别对焊接变形及残余应力进行分析,并通过焊接试验进行验证。结果表明:焊缝左右两侧的边缘区域是产生焊接残余应力的主要位置,横向、纵向残余应力分别为275 MPa、181 MPa,结构件上蒙板呈马鞍形分布,焊接所导致的最大变形分布在上蒙板左右两侧,左右两侧仿真最大值分别0.299 mm、0.274 mm,左右两侧试验最大值分别0.37 mm、0.34 mm,试验变形值略大于仿真变形值,两侧变形预测误差率分别为19.1%、19.4%。研究结果可为类似中空薄壁铝合金结构件焊接变形及残余应力预测提供一定参考依据。

Influence of upstream disturbance on the draft-tube flow of Francis turbine under part-load conditions

Owing to the part-load operations for the enhancement of grid flexibility, the Francis turbine often suffers from severe low-frequency and large-amplitude hydraulic instability, which is mostly pertinent to the highly unsteady swirling vortex rope in the draft tube. The influence of disturbances in the upstream（e.g., large-scale vortex structures in the spiral casing） on the draft-tube vortex flow is not well understood yet. In the present paper, the influence of the upstream disturbances on the vortical flow in the draft tube is studied based on the vortex identification method and the analysis of several important parameters（e.g., the swirl number and the velocity profile）. For a small guide vane opening（representing the part-load condition）, the vortices triggered in the spiral casing propagate downstream and significantly affect the swirling vortex-rope precession in the draft tube, leading to the changes of the intensity and the processional frequency of the swirling vortex rope. When the guide vane opening approaches the optimum one（representing the full-load condition）, the upstream disturbance becomes weaker and thus its influences on the downstream flow are very limited.

Improvement of part-load performance of gas turbine by adjusting compressor inlet air temperature and IGV opening

A novel adjusting method for improving gas turbine(GT)efficiency and surge margin(SM)under partload conditions is proposed.This method adopts the inlet air heating technology,which uses the waste heat of lowgrade heat source and the inlet guide vane(IGV)opening adjustment.Moreover,the regulation rules of the compressor inlet air temperature and the IGV opening are studied comprehensively to optimize GT performance.A model and calculation method for an equilibrium running line is adopted based on the characteristic curves of the compressor and turbine.The equilibrium running lines calculated through the calculation method involve three part-load conditions and three IGVopenings with different inlet air temperatures.The results show that there is an optimal matching relationship between IGV opening and inlet air temperature.For the best GT performance of a given load,the IGV could be adjusted according to inlet air temperature.In addition,inlet air heating has a considerable potential for the improvement of part-load performance of GT due to the increase in compressor efficiency,combustion efficiency,and turbine efficiency as well as turbine inlet temperature,when inlet air temperature is lower than the optimal value with different IGV openings.Further,when the IGV is in a full opening state and an optimal inlet air temperature is achieved by using the inlet air heating technology,GT efficiency and SM can be obviously higher than other IGVopenings.The IGV can be left unadjusted,even when the load is as low as 50%.These findings indicate that inlet air heating has a great potential to replace the IGV to regulate load because GT efficiency and SM can be remarkably improved,which is different from the traditional viewpoints.

Effects of propeller load fluctuations on performance and emission of a lean-burn natural gas engine at part-load conditions

Providing stable combustion of lean-burn natural gas engines was always a bigchallenge, particularly during a low load operation. In transient sea conditions, there is an additional concern due to irregular time-varying loads. Therefore, this study aimed at investigatingthe part-load operation of a marine spark-ignition lean-burn natural gas engine by simulatingthe entire engine. The engine’s essential components are modeled, including air manifold,intake valves, fuel system, controllers, combustion chamber, exhaust valves, exhaust manifoldand turbocharger.In steady-state, the results of emission compounds from modeling have been compared tomeasured data from 25% to 100% loads. For transient conditions, for the sample time of about50 min, the fuel flow and turbocharger output are selected from the vessel logged data andcompared with the simulation results. The model has shown the great potential of predictingthe engine response throughout the steady-state and transient conditions. Simulating the engineat part-load transient condition showed that the unburned hydrocarbon formation, known asmethane slip in lean-burn gas engines, is more than the part-load steady-state. This increaseof methane slip is due to the combustion instability in lower loads and flame extinguishingin such transient conditions. The engine measured data shows a double amount of methane slipin a 25% load than the 100% load in steady-state. However, the simulation output in the transient conditions confirms an increase in methane slip over four times than equivalentsteady-state load. Moreover, the lean-burn gas engine releases less NOX in part-load operationin a steady-state due to lower in-cylinder temperature. In transient conditions, there is remarkable instability in excess air ratio. Due to this instability, there is a rich mixture in instantaneoustime steps during loads up. Therefore, it will result in an unusually high amount of NOX, andmore than two times in comparison with the equivalent steady-state output.

随机振动载荷下机械零部件疲劳寿命预测研究

针对机械零部件疲劳寿命预测准度较低的问题,提出一种随机振动载荷下机械零部件疲劳寿命预测方法。对随机振动载荷下机械零部件开展疲劳分析,根据机械零部件的应力/应变响应,获取一定范围内的机械零部件疲劳部位应力功率谱密度函数。基于累计损伤理论和S-N曲线,进一步估算出随机振动载荷下机械零部件疲劳寿命,实现机械零部件寿命预测研究。实验结果表明,该方法的应力功率谱密度与实际结果一致,在不同振幅及预压量下的机械零部件疲劳寿命预测结果均较为准确,验证了该方法的可靠性高。

CFD investigation and PIV validation of flow field in a compact return diffuser under strong part-load conditions

The internal flow fields in a compact return diffuser under strong part-load conditions are investigated both numerically and experimentally.For numerical simulation,three-dimensional unsteady Reynolds-Averaged Navier–Stokes equations are solved on high-quality structured grids in conjunction with the shear stress transport k–turbulence model by employing the computational fluid dynamics(CFD)software ANSYS-Fluent 14.5.For flow field measurements,a special test rig is designed and the two-dimensional particle image velocimetry(PIV)measurements are conducted in the diffuser midplane to capture the complex flow field and for validation of the CFD results.The analysis of the results has been focused on the flow structure in the diffuser,especially under part-load conditions.The detailed comparison between CFD and PIV results is performed.Vortical flow and recirculation flow patterns in the diffuser are captured and analyzed.Large flow separation and backflow appear under the part-load flow conditions.This paper provides a good data set for developing as well as evaluating the accuracy of various CFD models for capturing the complex flow field in a compact return diffuser used with multistage pumps.

Part-load Performance Characteristics of a Lean Burn Catalytic Combustion Gas Turbine System

The purpose of this study is to compare the part-load performance of a lean burn catalytic combustion gas turbine (LBCCGT) system in three different control modes: varying fuel, bleeding off the fuel mixture flow after the compressor and varying rotational speed. The conversions of methane species for chemical process are considered. A 1D heterogeneous plug flow model was utilized to analyze the system performance. The actual turbomachinery components were designed and predicted performance maps were applied to system performance research. The part-load characteristics under three control strategies were numerically investigated. The main results show that: the combustor inlet temperature is a significant factor that can significantly affect the part-load characteristics of the LBCCGT system; the rotational speed control mode can provide the best performance characteristics for part-load operations; the operation range of the bleed off mode is narrower than that of the speed control mode and wider than that of the fuel only mode; with reduced power, methane does not achieve full conversion over the reactor at the fuel only control mode, which will not warrant stable operation of the turbine system; the thermal efficiency of the LBCCGT system at fuel only control strategy is higher than that at bleed off control strategy within the operation range.

地下车站冷水机组部分负荷性能系数研究

部分负荷性能系数的概念综合考虑了气象因素、实际负荷及运行条件,便于在更贴近实际使用条件下对机组进行比较、评价,有助于促进机组实际运行性能水平的提高,目前已被空调行业广泛采用。国标定义的部分负荷性能系数具有广谱性,力求覆盖全国各气候区及各种建筑类型。地铁车站应用场景下,空调负荷有其固有的特点,不宜直接采用国标定义的部分负荷性能系数定义工况点及计算方法。本文选取我国不同气候区域的代表城市,在深入研究地下车站空调负荷特点的基础上,提出适应于地下车站应用场景的部分负荷性能系数定义工况点及相应的计算方法。

供热机组低压缸零出力工况下热经济性分析

低压缸零出力运行是当前供热机组灵活性改造的主要方式。依据电网现行深调峰补偿政策,核算机组不同工况下的收益是现场面临的实际问题。研究一种基于热平衡规律的变工况快速算法,能够在保证基本计算准确度的情况下快速计算出机组变工况后运行状态。以某350 MW超临界供热机组为例,分别计算100%TMHCR(最大供热)和40%THA工况下低压缸零出力运行前后的发电功率、供热功率及热耗等参数,进而计算出发电供热收益。结果显示,100%TMHCR工况低压缸零出力运行能够降低发电负荷约8%,提升供热负荷27%,40%THA工况可将发电负荷降低至25%Pe,经济效益显著。

基于ABAQUS加载方式对零件加工过程材料性能影响分析

汽车用材加工过程复杂,加载方式并非一次直接加载过程,而是存在预加载的过程,采用单向拉伸获取的力学性能对其成形性进行评价误差较大。选取TRIP690作为研究材料,根据实际生产参数和实验条件,采用单向拉伸过程预应变方式,对单轴拉伸试样施加不同大小的预应变,主要为0%、5%、10%、15%等预应变量,紧接着再进行拉伸试验直至断裂失效,借此来评价材料在零件加工过程材料性能及变化规律;基于ABAQUS建立TRIP690体积元模型,模拟拉伸过程,获取残余奥氏体转变情况。对比分析结果可知:整个过程中,材料的强度均有所增加;在预应变后的继续拉伸阶段,TRIP效应不再明显;材料的初始加工硬化指数随着预应变量的增加而减小,瞬时加工硬化指数也呈现出相同的变化趋势;随着预应变量地增加,初始加工硬化指数降低,瞬时加工硬化指数呈现相同的变化趋势;在初始阶段加工硬化曲线下降到最低点,不施加预应变的试样加工硬化曲线最低点高于施加预应变的试样;软相铁素体在前期的塑性应变较高而随着应变量的增大,铁素体发生明显的加工硬化,与贝氏体的强度差减小,应变集中程度降低;试验过程和结果为成形过程分析提供参考。

基于响应面法的大型锥筒件内凸缘缩口成形工艺参数优化

目的探究大型锥筒件内凸缘缩口成形的最佳工艺参数。方法首先,根据内凸缘缩口成形的工艺原理,使用三维软件构建内凸缘缩口成形的仿真模型,并用Deform进行仿真成形。在此基础上,以缩口件高度和成形载荷作为内凸缘成形质量的判断依据,基于响应面法得到关于缩口件高度和成形载荷的回归预测模型。分析不同的摩擦因数、挤压速度和凹模锥度对内凸缘成形质量的影响,优化得到最佳的成形工艺参数,最后进行物理试验验证。结果通过响应面法拟合得到了缩口件高度和成形载荷关于3因素的多元非线性模型,模型通过F检验得出的显著性概率P值均小于0.0001,失拟项值均大于0.05,且模型预测值与试验模拟值的关系接近直线,充分说明了该数学模型的合理性。当摩擦因数为0.3、挤压速度为3 mm/s、凹模锥度为9°时,毛坯的成形载荷最小,为90 kN,缩口件高度最低,为1350 mm,与模型预测相比,误差均小于10%。结论优化后的工艺参数使内凸缘成形质量高、表面光滑无缺陷、成形载荷小,为大型锥筒的内凸缘成形工艺提供了参考。

掘进机铲板部的多元化探讨

介绍了不同掘进机上使用的铲板部,对铲板部做出了不同分类的介绍。对尺寸分类的铲板部做出了详细说明,针对其优点做出了分析解释,对应适合的巷道尺寸同时做出说明。对智能化、自动化掘进机适用的铲板做出了介绍及分析。再通过铲板的设计分析,确定控制集中点及注意事项以及焊接主要探伤位置,为设计工作提供意见,为掘进机使用者选择铲板部提供多元化、多角度的帮助。

高承载力钢板承插式牛腿受力性能试验研究

大跨桥梁超高桥塔的高速发展,对施工预埋件设计与施工的安全性、操作性、后期修复等方面提出了更高的要求。文中提出了一种钢板承插重型牛腿,该牛腿具有承载能力高(≥350 t)、可周转使用、对桥塔截面削弱小、易于修复等优点。通过数值分析与足尺加载试验,研究其受力性能及破坏模式。结果表明:钢板承插式牛腿在设计荷载作用下,牛腿应变-荷载大小基本呈线性,卸载后未出现明显的局部皱折和屈曲。锚固混凝土的破坏形态为受压侧冲切引起的斜裂缝,裂缝宽度满足限值要求,卸载后裂缝闭合,对永久结构无不利影响。钢板承插式牛腿受力性能良好,可作为大牛腿的选型,研究成果可为重型预埋件的进一步研究应用提供参考。

高铁客站空调系统冷水机组设计能耗预测

目前全年空调能耗一般通过性能化模拟得出,其模拟需要准确的边界条件,且计算过程烦琐,而众多大、中、小型高铁客站冷负荷采用典型设计日进行计算,无法给出全年空调系统设计预测能耗和实际运行能耗.本文利用综合部分负荷性能系数(IPLV)的概念,以夏热冬冷地区某高铁客站为例,分析并给出了其冷水机组不同负荷率下的COP和运行时长的计算方法.在设计阶段对能耗进行相对准确的简单估算,为实现定量控制空调系统能耗及碳排放目标提供支持.

基于液体载冷剂法的空调器性能测量不确定度分析

基于液体载冷剂法,应用间接测量参数的不确定度理论,建立了空调器性能参数的标准不确定度计算模型,给出了基于液体载冷剂法性能测量参数的标准不确定度评价方法。以水冷冷水机组综合部分负荷性能系数的标准不确定度评定为例进行分析。结果表明:进出水温度测量引入的标准不确定度对水冷冷水机组的综合部分负荷性能系数影响较大,其次是水流量和功率测量因素;综合部分负荷性能系数的A类标准不确定度远小于B类标准不确定度。因此,在测量水冷冷水机组综合部分负荷性能时,需要重点关注仪器仪表的精度,较高的仪器仪表精度能有效降低水冷冷水机组性能参数的测量不确定度。

大型过山车车体剩余使用寿命评估研究

本文以大型过山车为研究对象,基于游乐设施剩余寿命评估理论,从疲劳、磨损和锈蚀这三个影响大型游乐设施主要受力部件剩余使用寿命的因素出发,对四环过山车车体的重要结构件和重要销轴进行了应力测试和尺寸测量,以测试和测量数据为基础对其进行了疲劳寿命分析、磨损和锈蚀寿命分析,得到了车体重要结构件和重要销轴的剩余使用寿命,进而得到了四环过山车车体的剩余使用寿命为1×105次,折算后的使用期限约为5年8个月。