A Financial Approach to Evaluate an Optimized Combined Cooling, Heat and Power System

Iran’s removing subsidy from energy carrier in four years ago leads to spike electricity price dramatically. This abrupt change increases the interest on distributed generation (DG) because of its several benefits such as lower electricity generation price. In Iran among all type of DGs, because of wide natural gas network infrastructure and several incentives that government legislated to support combined cooling, heat and power (CCHP) investors, this type of technology is more prevalent in comparison with other technologies. Between existing CCHP technologies, certain economic choices are to be taken into account. For different buildings with different load curves, suitable size and operation of CCHP should be calculated to make the project more feasible. If CCHP does not well suited for a position, then the whole energy efficiency would be plunged significantly. In this paper, a model to find the optimal size and operation of CCHP and auxiliary boiler for any users is proposed by considering an integrated view of electricity and natural gas network using GAMS software. Then this method is applying for a hospital in Tehran as a real case study. Finally, by applying COMFAR III software, useful financial parameters and sensitivity analysis are calculated.

Thermal-environment characteristics and comfort of combined radiant-floor (Korean heating system ondol) and convective cooling system

The thermal-environment characteristics of the existing forced-convection cooling system were compared with those of the convective cooling system, which combined the radiant-floor cooling system using floor-heating panel typically applied to apartments in South Korea with the forced-convection cooling system using improved fan coil unit. The subjective warm/cool-feeling responses to the combined radiant-floor and convective cooling system in the questionnaire survey conducted among the test subjects were analyzed to establish the basic data for the combined cooling system. The results show that in the thermal-equilibrium condition, the vertical air temperature difference in the model living room is larger in the forced-convection-cooling condition. Most of the subjects feel a proper warm/cool feeling on their entire body, but they feel colder on the foot and lower body in the combined-cooling condition.

Application Research of Intake-Air Cooling Technologies in Gas-Steam Combined Cycle Power Plants in China

The generated power and efficiency of gas-steam combined cycle (GSCC) power plants depend on the temperature of the inlet air greatly. Based on the analysis of basic theory of inlet air cooling technologies, the application of evaporative cooling system and the absorption cooling system in GSCC power plants are discussed in this paper. Moreover, in China with high temperature and humidity, applied research and simulation analysis of the above two different cooling systems are conducted separately, the research results of which can provide certain reference for optimal design and economic operation of inlet air cooling system for GSCC power enterprises in China.

Initiative Optimization Operation Strategy and Multi-objective Energy Management Method for Combined Cooling Heating and Power

This paper proposed an initiative optimization operation strategy and multi-objective energy management method for combined cooling heating and power U+0028 CCHP U+0029 with storage systems. Initially, the initiative optimization operation strategy of CCHP system in the cooling season, the heating season and the transition season was formulated. The energy management of CCHP system was optimized by the multi-objective optimization model with maximum daily energy efficiency, minimum daily carbon emissions and minimum daily operation cost based on the proposed initiative optimization operation strategy. Furthermore, the pareto optimal solution set was solved by using the niche particle swarm multi-objective optimization algorithm. Ultimately, the most satisfactory energy management scheme was obtained by using the technique for order preference by similarity to ideal solution U+0028 TOPSIS U+0029 method. A case study of CCHP system used in a hospital in the north of China validated the effectiveness of this method. The results showed that the satisfactory energy management scheme of CCHP system was obtained based on this initiative optimization operation strategy and multi-objective energy management method. The CCHP system has achieved better energy efficiency, environmental protection and economic benefits. © 2014 Chinese Association of Automation.

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.

Multi-Objective Optimization Based on Life Cycle Assessment for Hybrid Solar and Biomass Combined Cooling,Heating and Power System

The complementary of biomass and solar energy in combined cooling,heating and power(CCHP)system provides an efficient solution to address the energy crisis and environmental pollutants.This work aims to propose a multi-objective optimization model based on the life cycle assessment(LCA)method for the optimal design of hybrid solar and biomass system.The life-cycle process of the poly-generation system is divided into six phases to analyze energy consumption and greenhouse gas emissions.The comprehensive performances of the hybrid system are optimized by incorporating the evaluation criteria,including environmental impact in the whole life cycle,renewable energy contribution and economic benefit.The non-dominated sorting genetic algorithmⅡ(NSGA-Ⅱ)with the technique for order preference by similarity to ideal solution(TOPSIS)method is employed to search the Pareto frontier result and thereby achieve optimal performance.The developed optimization methodology is used for a case study in an industrial park.The results indicate that the best performance from the optimized hybrid system is reached with the environmental impact load reduction rate(EILRR)of 46.03%,renewable energy contribution proportion(RECP)of 92.73%and annual total cost saving rate(ATCSR)of35.75%,respectively.By comparing pollutant-eq emissions of different stages,the operation phase emits the largest pollutant followed by the phase of raw material acquisition.Overall,this study reveals that the proposed multi-objective optimization model integrated with LCA method delivers an alternative path for the design and optimization of more sustainable CCHP system.

Improved Design of a 25 MW Gas Turbine Plant Using Combined Cycle Application

This paper presents the improved design of a 25 MW gas turbine power plant at Omoku in the Niger Delta area of Nigeria, using combined cycle application. It entails retrofitting a steam bottoming plant to the existing 25 MW gas turbine plant by incorporating a heat recovery steam generator. The focus is to improve performance as well as reduction in total emission to the environment. Direct data collection was performed from the HMI monitoring screen, log books and manufacturer’s manual. Employing the application of MATLAB, the thermodynamics equations were modeled and appropriate parameters of the various components of the steam turbine power plant were determined. The results show that the combined cycle system had a total power output of 37.9 MW, made up of 25.0 MW from the gas turbine power plant and 12.9 MW (an increase of about 51%) from the steam turbine plant, having an HRSG, condenser and feed pump capacities of 42.46 MW, 29.61 MW and 1.76 MW respectively. The condenser cooling water parameters include a mass flow of 1180.42 kg/s, inlet and outlet temperatures of 29.8°C and 35.8°C respectively. The cycle efficiency of the dry mode gas turbine was 26.6% whereas, after modification, the combined cycle power plant overall efficiency is 48.8% (about 84% increases). Hence, SIEMENS steam turbine product of MODEL: SST-150 was recommended as the steam bottoming plant. Also the work reveals that a heat flow of about 42.46 MW which was otherwise being wasted in the exhaust gas of the 25 MW gas turbine power plant could be converted to 12.9 MW of electric power, thus reducing the total emission to the environment.

THERMAL DESIGN FOR HARMON DRY-COOLING SYSTEM IN LARGE POWER STATION

Based on the analysis of air flow and heat transfer in the dry-cooling towerfor Harmon system, a combined iteration method is presented to solve the coupled heat transfer anddraft equations derived from theoretical and empirical formulas, with the size of the exchangers andthe cooling tower or the systematic parameters being determined. Taking the 686 MW unit as anexample, the present calculating results are well agreed with those of the real case, and thus themethod presented is practical and feasible for reasonable design of Harmon system.

Thermodynamic Analysis of Solid Oxide Fuel Cell Based Combined Cooling,Heating,and Power System Integrated with Solar-Assisted Electrolytic Cell

Syngas fuel such as hydrogen and carbon monoxide generated by solar energy is a promising method to use solar energy and overcome its fluctuation effectively.This study proposes a combined cooling,heating,and power system using the reversible solid oxide fuel cell assisted by solar energy to produce solar fuel and then supply energy products for users during the period without solar radiation.The system runs a solar-assisted solid oxide electrolysis cell mode and a solid oxide fuel cell mode.The thermodynamic models are constructed,and the energetic and exergetic performances are analyzed.Under the design work conditions,the SOEC mode’s overall system energy and exergy efficiencies are 19.0%and 20.5%,respectively.The electrical,energy and exergy efficiencies in the SOFC mode are 51.4%,71.3%,and 45.2%,respectively.The solid oxide fuel cell accounts for 60.0%of total exergy destruction,caused by the electrochemical reactions’thermodynamic irreversibilities.The increase of operating temperature of solid oxide fuel cell from 800℃to 1050℃rises the exergy and energy efficiencies by 11.3%and 12.3%,respectively.Its pressure from 0.2 to 0.7 MPa improves electrical efficiency by 13.8%while decreasing energy and exergy efficiencies by 5.2%and 6.0%,respectively.

基于全生命周期评价的冷热电联供系统优化研究

天然气与太阳能互补是提高能源利用率和实现节能减排的有效方法,该文构建一种光-气-储互补的冷热电联供(CCHP)系统。基于全生命周期理论,以一次能源节约率、总污染物减排率为目标函数,建立冷热电联供系统优化模型,应用遗传算法对系统变工况运行下的容量配置进行优化;将物质回收阶段纳入全生命周期评价,并在运输阶段考虑燃料运输。结果表明:经优化后,CCHP系统电跟随(FEL)策略可实现较好的节能减排效益。分供(SP)系统在物质回收阶段对环境的影响微乎其微,CCHP系统燃料运输能耗量远低于SP系统。

联合收获机发动机风冷系统优化设计

为了减少联合收获机收获过程中水箱“开锅”现象的发生,延长收获机的无故障工作时长,对4LXZ-8F型联合收获机的发动机风冷系统散热量进行了计算,并基于计算结果对防尘罩、散热器进行了优化设计,对冷却风扇进行了匹配选型。利用SolidWorks对优化前后风冷系统进行了三维建模,利用Fluent软件对发动机风冷系统优化前和优化后散热器散热性能分别进行仿真分析。仿真结果表明:优化前的冷却水入口温度为90℃,出口温度为72.3℃,进出口温差为17.7℃;优化后的冷却水入口温度为90℃,出口温度为71.1℃,进出口温差为18.9℃,表明优化后散热器散热性能提升了6.78%。研究成果可为提高发动机风冷系统的散热性能,延长无故障收获时长提供理论指导。

超燃冲压发动机燃烧室三种冷却结构性能比较

面对超燃冲压发动机燃烧室严峻热环境,需要通过改进设计以提高气膜冷却性能。本文用数值方法分析比较了三种不同于传统气膜冷却的结构:(1)沿冷气通道增加气膜孔直径的改进型气膜冷却结构;(2)增加冷气冲击与对流换热的层板冷却结构;(3)增加多孔板的发散气膜组合冷却结构。通过机理实验数据验证数学模型和数值方法。利用经过验证的模型和方法,在真实的超燃冲压发动机燃烧室工况下,数值分析三种结构的冷却机理。在不同冷气注射量下,比较三种冷却结构热端冷却效率及温度分布的均匀性,结果表明组合冷却结构最高冷却效率高出其他结构的28%。此外,分析热障涂层对三种结构综合冷却特性的贡献,结果表明层板结构冷却效率在大冷气量下高出其他结构的16%。

竖向和水平组合荷载下能量桩单桩变形特性

能量桩作为一种新型能源地下结构,在承受上部建筑荷载同时,能够获取浅层地热能。目前针对水平荷载与竖向荷载共同作用下的能量桩热力学特性的研究较少,而水平荷载与竖向荷载共同作用下,桩身温度变化会引起桩体弯矩、水平和竖向位移等发生变化。基于模型试验,对桩体施加10次冷热循环,开展了竖向和水平组合荷载下能量桩的变形特性研究。结果表明,组合荷载下冷热循环会进一步增大桩身弯矩,且对桩体中部的影响更大,最大桩身弯矩增幅达到了117%;冷热循环会产生桩顶累积位移,试验桩竖向位移增加了0.201 mm,温度作用引起的水平位移增加值达到了1.46%D(D为桩体直径);同时,冷热循环会导致桩向桩前倾斜,10次冷热循环后转角达到1.88×10^(-3)rad,且会随着循环次数增加有缓慢增加趋势;加热时桩前土压力减小,而制冷时使桩前土压力增大。

膜调控的头孢呋辛钠溶析-冷却耦合结晶成核介稳区测定及分析

溶析-冷却耦合结晶可以提高结晶产率的同时,降低溶析剂的消耗量,是一种高效的耦合分离过程。传统的溶析结晶传质的界面往往受到宏观混合规模的限制,传质调控通常为亚毫米级,容易爆发成核,导致结晶产品的纯度差、平均粒度小、晶体粒度分布宽,因而需要更精确的调节策略。本文提出了一种新型的膜辅助溶析-冷却耦合结晶的方法,应用于头孢呋辛钠的结晶过程研究。其中,聚四氟乙烯(PTFE)中空纤维膜作为精确添加溶析剂和高效混合的界面,实现过饱和度的均匀分布。为了对比膜辅助溶析-冷却耦合结晶和传统耦合结晶方式的调控效果,对膜辅助溶析-冷却耦合结晶过程进行更为精确的调控,分别测量了传统和膜辅助条件下溶析-冷却耦合结晶的头孢呋辛钠-水-乙醇体系的介稳区宽度,计算了成核动力学参数。使用响应面方法和理论模型分析了冷却速率、溶析剂添加速率和溶析剂组分对介稳区宽度的影响,并比较了传统结晶和膜辅助结晶的介稳区特征。结果表明,膜辅助溶析-冷却耦合结晶的成核级数和成核速率常数(n=2.07,kn=158.15)均小于常规耦合结晶(n=2.45,kn=493.22),成核动力学方面更加温和,可调控性更强。

含分层储能的冷热电联供系统运行优化

为提高冷热电联供型微电网对可再生能源的消纳能力,解决源-荷的不确定性使得系统运行稳定性降低的问题,提出含分层储能的三级混合时间尺度滚动优化方法。日前优化目标为日运行成本最低;日内上层以燃料成本和蓄热罐功率变化惩罚成本最低为目标对冷热能进行优化,下层以电网交互成本和蓄电池功率变化惩罚成本最低为优化目标对电能进行优化;实时电系统反馈以电系统削峰填谷作用量和功率波动量最低为优化目标;得出最优的系统中各设备的出力计划。结果表明:该优化方法和分层储能能够有效达到削峰填谷的作用,各设备功率波动率均处于较低水平;冬季典型日的日运行成本比日前成本有所降低。

风冷高炉矿渣的超细粉磨与化学激发联合活化研究

风冷高炉矿渣水化活性低,某企业工业试验中使用风冷高炉矿渣作混合材生产复合水泥时,矿粉在水泥中的掺量通常低于30%。本文提出超细粉磨和化学激发联合活化的技术思路,改造粉磨工艺实现风冷高炉矿渣超细粉磨,并探究了粉磨工艺参数对矿粉粒径和活性指数的影响,当矿粉比表面积为650 m^(2)/kg时,28 d活性指数为88.4%,比原生矿粉提高了26.2%。在化学激发方面则研究了激发剂种类、掺量以及多元复配对矿粉活性的影响,最终以硫酸钠、硫酸铝钾和三乙醇胺为主要成分制备了一款复合激发剂,矿粉粉磨过程引入1.5%复合激发剂即可使7 d活性指数提高16.9%。

计及风光储的冷热电联产综合能源系统低碳经济优化

为解决能源危机,中国大力发展综合能源系统,以期进行多能协同互济,实现节能降碳。主要研究计及风光储的冷热电联供系统多目标优化调度问题。首先,从经济和碳排放2个不同的角度出发,建立经济目标函数和环境目标函数,构造考虑风光储的冷热电联供系统多目标优化配置模型以及相应的约束条件;然后,提出增强的非支配排序遗传算法Ⅱ(non-dominated sorting genetic algorithmⅡ,NSGA-Ⅱ),通过引入支配强度和方差因子,提高算法求解效率和求解精度;最后,以辽西某地正在运行的冷热电联供系统为例进行仿真分析,验证本文所提模型和方法的有效性。

基于奖惩机制碳交易的综合能源系统供需双响应低碳调控

随着能源市场的深化改革,需求响应资源在综合能源系统低碳运行中的重要作用日益凸显。文章针对综合能源系统提出了一个考虑阶梯型碳交易及供需双向响应的新策略。首先,建立了一个包含奖惩机制的阶梯型碳交易综合能源系统模型,基于此模型,进一步提出了供需双向响应及其补偿机制;其次,针对该系统构建了一个优化调度模型,目标函数旨在最小化运营成本、需求响应补偿成本及碳交易成本的总和;最后,应用CPLEX工具箱对优化模型进行仿真求解。通过不同情景下的案例分析,探讨了供需双向响应策略与碳交易机制对系统运行的影响。仿真结果验证了提出策略的有效性和优越性。

基于天然气、地热能和太阳能的多能源耦合系统优化研究

该文基于冷热电三联供系统、地源热泵、光伏和光热耦合的多能源耦合系统,构建了多能源耦合系统全工况优化模型,以能源、经济、环境的综合指标为优化目标,以燃气轮机的额定容量、决定是否运行燃气轮机的关键值、地源热泵供能与建筑负荷的比率、光伏面积和光热面积为优化变量,基于优先满足建筑总热需求的运行策略,以系统冷热电平衡和设备容量为约束,以粒子群算法对优化模型进行优化.提出的优化模型应用于北京的一栋宾馆建筑,得到了优化后系统的最优设备容量与运行策略,为多能源耦合系统的优化提供了参考.

火电厂源侧综合能源系统集成及性能评估研究

本文建立了以火电厂为核心,消纳可再生能源并提供冷热电汽综合能源服务的一套能源系统,通过对整体系统及关键子系统热力性能分析,验证了提出模型和方法的有效性。并研究了一些关键运行参数对系统综合性能的影响,验证了提出模型和方法的有效性和优越性。结果表明:通过改变火电厂的源侧参数,可以提高综合能源系统荷侧的输出量;且生物质转化气对汽轮机发电功率的影响最大。热泵系统的负荷随着进入系统中的给水流量的增大而增大,利用汽轮机中的部分抽汽来驱动热泵系统,虽然发电功率下降了10.88%,但是却为用户提供了16.8MW的热负荷和16.2MW的冷负荷以及27.78t/h的蒸汽量。