基于滚动优化的电-热-气-冷系统多时间尺度低碳运行

电-热-气-冷多能联供型微网对实现能源可持续发展具有重要的应用价值。针对多能联供系统碳排放量较高和负荷模型预测不准确问题,提出了一种基于滚动优化的电-热-气-冷系统多时间尺度低碳运行策略。首先,建立电-热-气-冷系统设备模型。其次,构建日前与日内两阶段模型,在日前调度阶段引入含赏罚因数的碳交易机制,通过将卷积神经网络(convolutional neural networks,CNN)与双向长短期记忆网络(bi-directional long short term memory,Bi-LSTM)进行结合对风光功率进行预测,并以运行成本最低为目标进行优化。之后,建立日内多时间尺度的优化调度模型,以调度成本最低为目标进行求解。最后,以某市综合能源系统为研究对象进行分析。结果表明,所提出的方法能够有效减少碳排放,提高负荷模型预测的准确度的同时实现多能联供系统的低碳经济运行。

Niche-PSO算法在建筑冷-热-电综合能源自动化调度中的应用

综合能源需求的多样化,给建筑冷-热-电综合能源自动化调度带来挑战。为优化建筑冷-热-电综合能源自动化调度效果,提出了基于小生境粒子群算法的综合能源自动化调度方法,首先,构建建筑冷-热-电综合能源自动化调度数学模型;随后,利用小生境技术对粒子群算法进行优化,提出采用小生境粒子群优化算法对调度模型进行求解;最后对该方法的有效性进行了检验。结果显示,能源浪费显著降低,夏季购电成本为2100元,相较于未优化方法降低了2100元。这表明,该方法提高了对各种能源的利用率,降低了综合能源系统运行的经济成本,有利于减少城市环境污染,推动城市的可持续性发展。

含电-热-冷-气负荷的园区综合能源系统经济优化调度研究

综合能源系统是实现各能源系统间有机协调优化的重要途径。剖析电-热-冷-气4个子系统,构建以建设运行总成本为目标的园区综合能源系统经济优化调度模型;其次,利用非线性问题处理办法将所构建的调度模型转化为混合整数规划问题;最后,基于子系统独立运行和耦合调度的2种场景,结合分时电价调用混合整数规划软件对模型进行求解。结果显示,相对于独立运行方式,各子系统耦合调度运行能够灵活组合各能源转换设备,大大降低系统外部购能和系统总成本。

含电—热—气—冷子系统的区域综合能源系统多场景优化调度

针对当前区域综合能源系统(RIES)研究中未详细考虑含电-热-气-冷子系统(PHGCS)协调运行效果的现状,研究计及能源子系统关键特征变量的RIES多场景优化问题。首先,基于能源集线器概念对以区域混合能源站为核心的能源耦合环节进行能源比例分配建模及分析,分别建立RIES中PHGCS数学模型。然后,提出考虑效率指标最大化、费用指标最小化、排放指标最小化及多目标综合性能指标最优的多场景运行模式,建立在不同负荷结构、多时段、多场景运行模式下的优化分析模型。其次,采用峰谷分时电价机制对RIES整体和分时段性能指标、子系统及耦合环节关键特征变量进行综合分析。最后,通过算例验证了该模型与优化方法的合理性和有效性。

Parametric optimization of power system for a micro-CCHP system

The universal mathematical model of an engine is established,and an economical zone,in which an engine mainly provides medium output load at medium speed,is presented.Based on the experimental data and the universal model of such an engine above,a mathematical model of a refitted engine is provided.The boundary of the corresponding economical zone is further demarcated,and the optimal operating curve and the operating point of the engine are analyzed.Then,the energy transforming models of the power system are established in the mode of cooling,heating and power（MCHP）,the mode of heating and power（MHP）and the mode of electricity powering（MEP）.The parameter matching of the power system is optimized according to the transmission ratios of the gear box in the power distribution system.The results show that,in the MCHP,the speed transmission ratio of the engine to the gear box（ies）and the speed transmission ratio of the motor to the gear box（ims）are defined as 2.9 and 1,respectively;in the MHP,when the demand load of the power system is less than the low critical load of the economical zone,the speed transmission ratio of the motor to the engine（ime）is equal to 1,and when the demand load of the power system exceeds the low critical load of the economical zone,ime equals 0.85;in the MEP,the optimal value of ims is defined as 2.5.

Performance analysis of aircraft low-power thermoelectric refrigeration system

An optimal design method for an aircraft low-power thermoelectric refrigeration system（TRS）is proposed using an existing experimental model as the research platform under given aircraft flight conditions.The variation curves of the cooling capacities and the refrigeration coefficients of the system running at three flight altitudes are investigated.The performance of the system is evaluated by the minimum-entropy-generation method and the performance penalty is also calculated.The power variation curves of the cooling system are obtained by an electric power experiment.The peak values of these curves are less than the maximal electric power supply of airborne equipment,proving that the use of the low-power TRS for airborne equipment is feasible.The COP,cooling capacity and entropy generation of the system are relative to the flight altitude and the current of the TRS.Through the analyses of these data,the optimal values of the COP are obtained,and the optimization measures are proposed to maximize the use of the advantages of the TRS.

计及光热电站和“源荷”双侧博弈的综合能源系统优化运行

为响应减碳减排计划、提高新能源渗透率同时缓解传统能源系统出现的弃风弃光以及污染排放现象,本文引入光热电站联合风电、光伏等新型能源生产设备,建立了计及光热电站的综合能源系统主从博弈模型,同时考虑风光出力不确定性以及用户侧的综合需求响应问题。运用NSGA-Ⅱ嵌套智能求解器对该模型进行求解。分析光热聚合商、多能运营商和用户三方的利益均衡,研究对比三个不同的场景,通过算例验证该模型的可行性以及方法的有效性。结果表明含光热电站的综合能源系统结合主从博弈方法在有效地提升用户侧用能满意度的同时提高了系统的经济效益。

Dropwise condensation heat transfer enhancement on surfaces micro/nano structured by a two-step electrodeposition process

Condensation is an important regime of heat transfer which has wide applications in different industries such as power plants,heating,ventilating and air conditioning,and refrigeration.Condensation occurs in two different modes including filmwise (FWC) and dropwise (DWC) condensation.DWC occurring on hydrophobic and superhydrophobic surfaces has a much higher heat transfer capacity than FWC.Therefore,wide investigations have been done to produce DWC in recent years.Superhydrophobic surfaces have micro/nano structures with low surface energy.In this study,a two-step electrodeposition process is used to produce micro/nano structures on copper specimens.The surface energy of specimens is reduced by a self-assembled monolayer using ethanol and 1-octadecanethiol solution.The results show that there is an optimum condition for electrodeposition parameters.For example,a surface prepared by 2000 s step time has 5 times greater heat transfer than FWC while a surface with 4000 s step time has nearly the same heat transfer as FWC.The surfaces of the fabricated specimens are examined using XRD and SEM analyses.The SEM analyses of the surfaces show that there are some micro-structures on the surfaces and the surface porosities are reduced by increasing the second step electrodeposition time.

Water, Air Emissions, and Cost Impacts of Air-Cooled Microturbines for Combined Cooling, Heating, and Power Systems： A Case Study in the Atlanta Region

The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.

Quantitative contributions of solution atoms, precipitates and deformation to microstructures and properties of Al-Sc-Zr alloys

In order to investigate the effects of solid solution atoms, precipitated particles and cold deformation on the microstructures and properties of Al-Sc-Zr alloys, the Al-Sc-Zr alloys prepared by continuous rheo-extrusion were treated by thermomechanical treatment, analyzed for conductivity and mechanical properties by tensile and microhardness testing, and characterized using optical microscope, TEM and STEM. A mathematical model was established to quantitatively characterize the contribution of solid solution atoms, precipitates and cold deformation to the conductivity of the alloy. The results show that the strength of Al alloy can be significantly improved by solid solution, aging and cold deformation, and the quantitative impacts of solution atoms, precipitates and cold deformation on the conductivity of Al alloy are 10.5%(IACS), 2.3%(IACS) and 0.5%(IACS), respectively. Aging and cold deformation treatments are the keys to obtain high-strength and high-conductivity aluminum alloy wires.

Experimental study on heat generation and dissipation performance of PEV Lithium-ion battery

Based on the lithium-ion battery pure electric vehicle （PEV） application, two capacity types of batteries are applied in thermal characteristic experiments. With the experimental comparison method, battery thermal characteristics and heat generation mechanism are studied. Experiments of batteries in cases of different dimensions, batteries with different air cooling velocity and two capacity types of batteries in free convection environment are put forward. Battery heat generation performance, heat dissipation performance and comparison of different capacity types＇ batteries are researched and summarized. Conclusions of battery heat generation and dissipation in PEV applications, important battery thermal management factors and suggestions are put forward.

Analysis by Indicators Performance of the Conceptual Structures mCCHP-SE Using Renewable Energy Sources

This paper refers to an integrated mCCHP （micro-combined cooling heat and power） systems dedicated for isolated residents with energetic independence. The only energy sources are wood pellet and solar energy. The proposed trigeneration system is based on mCHP （micro-combined heat and power） unit with Stirling engine, photovoltaic panels, thermal solar collector and pellet boiler. The proposed mCCHP system utilizes the exceeding amount of heat in the summer for producing the necessary cooling. A residential building with known energy consumption is determined load curves that must be covered by mCCHP system. The paper analyzes four structures of trigeneration systems with thermal activation chiller and two structures of trigeneration systems with mechanical compression chiller. Performance indicators are determined based on energy balance equations for each variant. It compares the performances and establishes the best option.

Prediction Model for Cooling of an Electrical Unit with Time-Dependent Heat Generation

The satisfactory performance of electrical equipments depends on their operating temperature. In order to maintain these devices within the safe temperature limits, an effective cooling is needed. High heat transfer rate of compact in size and reliable operation are the challenges of a thermal design engineer of electronic equipment. Then, it has been simulated the transient a three-dimensional model to study the heating phenomenon with two assumption values of heat generation. To control for the working of this equipment, cooling process was modeled by choosing one from different cooling technique. Constant low speed fan at one direction of air flow was used for cooling to predict the reducing of heating temperature through working of this equipment. Numerical Solution of finite difference time domain method （FDTD） has been utilized to simulate the temporal and spatial temperature profiles through two processes, which would minimize the solution errors.

计及柔性负荷和碳流的园区综合能源系统优化运行模型研究

为了抑制碳排放总量的上升,同时平抑负荷波动并提升能源设备之间的耦合程度,提出计及柔性负荷和碳流的园区综合能源系统优化调度模型,探究其在不同运行条件下的优劣状况。首先,建立以运行成本和碳交易成本最优为目标的调度函数。然后,在能源供给单元侧,将耦合设备进行协同配置以优化能源之间的互补效益;在负荷需求单元侧,纳入柔性需求响应模型平滑负荷曲线。最后,结合分时电价利用混合整数规划软件对所建系统运行模型进行调度。仿真实验结果显示,计及园区综合能源系统的源荷供需双向联合优化不仅可以有效遏止碳排放量的水平,而且还能进一步提升系统的整体经济效益。

考虑碳交易成本的园区综合能源系统运行优化

充分考虑工业园区用能、降碳需求,结合不同能源转换的耦合关系及设备运行特点,对园区典型设备进行建模,并采取合适的约束条件进行安全管控;引入碳排放成本精确计算方法,结合碳排放分配额量化碳交易成本,以经济性、低碳性为目标,提出园区综合能源系统运行优化方法。以某工业园区为算例,在MATLAB环境下使用Yalmip语法编程并调用Gurobi求解器求解,将所建立的非线性模型转换为易于求解的MILP问题,并对子系统分立运行以及综合能源系统优化运行两种场景下的结果进行对比分析。结果表明,构建基于碳交易的园区综合能源系统及进行优化方法对实现节能减碳、降低成本有着显著效果。

天然气三联供技术在城市综合体中应用分析

天然气冷-热-电三联供技术是一种建立在能源梯级利用基础上,制冷、供热和发电过程一体化综合应用的多联产系统。在城市综合体项目中应用天然气冷-热-电三联供技术,不但通过发电自用减缓城市供电压力,还能够充分利用余热资源为建筑提供采暖、制冷和生活热水,减少常规能源的消耗,具有良好的经济、环境和社会效益。在能源环境危机日益突出的当代社会,天然气三联供技术将会得到广泛的应用。

OPTIMAL PERFORMANCE OF THERMOELECTRIC REFRIGERATION SYSTEM USING ENTROPY GENERATION MINIMIZATION METHOD

With the entropy generation minimization （EGM） method, the thermodynamical performance optimization in a thermoelectric refrigeration system is studied. The optimization is affected by the irreversibility of heat transfer caused by finite temperature differences, the heat leak between external heat reservoirs and the internal dissipation of working fluids. EGM is taken as an objective function for the optimization. The objective function and design parameters are obtained. Optimal performance curves are presented by thermal and electronic parameters. Effects of these parameters on general and optimal performances are investigated. Results are helpful in determining optimal design conditions in real thermoelectric refrigeration systems.

面向能源互联网的综合能源系统规划研究综述

能源互联网是满足能源消费需求,打造未来可持续发展能源生态圈的关键所在。综合能源系统作为能源互联网的根本物理实现,对其进行合理规划是实现多能源间协调高效、低碳运行的基本保障。首先,概述了各能源子系统的基本规划方法与综合能源系统联合规划的框架,梳理了系统间耦合环节模型。其次,按耦合子系统类型分类,对“电-气”“电-气-热/冷”的耦合系统的联合规划文献进行了详细地综述和分析。最后,提出了对综合能源系统联合规划领域的未来展望。

Performance Research of a Micro-CCHP System with Adsorption Chiller

This paper describes a new micro-combined cooling, heating and power （CCHP） system, which is especially suitable for domestic and light commercial applications. It mainly consists of a natural gas-fired internal combustion engine, a silica gel-water adsorption chiller and other heat recovery units. In order to study the energy efficiency and economic feasibility, an experimental investigation has been carried out. The experimental system has a rated electricity power of 12 kW, a rated cooling capacity of 9 kW and a rated heating capacity of 28 kW. Evaluation and analysis of the system are discussed in detail. The testing results show that the energy efficiency of the overall system depends on different modes. The overall thermal and electrical efficiency is over 70%. Higher heat load supplied causes higher efficiency of the system. Economic evaluation shows that the micro-CCHP system enjoys a small capital cost and short payback period, which is easily accepted by customers. At current natural gas price of 1.9 RMB/m^3 （nominal condition） and electric price of 0.754 RMB/（kW.h）, the total capital cost is only 90 000 RMB with a payback period of 3.21 years.

Analysis of an electricity-cooling cogeneration system for waste heat recovery of gaseous fuel engines

Waste heat recovery(WHR)is one of the most useful ways to improve the efficiency of internal combustion engines,and an electricity-cooling cogeneration system(ECCS)based on Rankin-absorption refrigeration combined cycle for the WHR of gaseous fuel engines is proposed in the paper.This system can avoid wasting the heat in condenser so that the efficiency of the whole WHR system improves,but the condensing temperature of Rankin cycle(RC)must increase in order to use absorption refrigeration system,which leads to the decrease of RC output power.Therefore,the relationship between the profit of absorption refrigeration system and the loss of RC in this combined system is the mainly studied content in the paper.Because the energy quality of cooling and electricity are different,cooling power in absorption refrigeration is converted to corresponding electrical power consumed by electric cooling system,which is defined as equivalent electrical power.With this method,the effects of some important operation parameters on the performance of the ECCS are researched,and the equivalent efficiency,exergy efficiency and primary energy rate are compared in the paper.