内燃机、燃气轮机和微燃机在冷热电联供系统中的性能分析

首先对内燃机、燃气轮机以及微燃机在发电效率、余热特性、变负荷特性、环境影响以及经济性能等方面进行了分析,通过分析,得出了不同动力装置的适用场合;以北京市某小型宾馆为应用对象,拟采用内燃机冷热电联供系统和微燃机冷热电联供系统作为该宾馆的供能系统,在满足宾馆用能需求的前提下,分析比较了这两种系统在变负荷条件下的天然气耗量、一次能源利用率等方面,最后分析了冷热电联供系统高效发展的瓶颈问题,通过分析得到以下结论:从燃气耗量和一次能源利用率两方面来看,内燃机冷热电联供系统在该类型的建筑中更具优势;冷热电联供系统与用户间的供需不匹配问题是制约其高效率发展的重要瓶颈。     

楼宇冷热电联供系统节能性研究

以济南地区一幢六层住宅楼冷、热、电负荷计算为基础,对基于小型燃气内燃机和微型燃气轮机的楼宇冷热电联供系统进行节能性研究。对系统余热利用情况和一次能耗率PER值进行计算,并将计算结果与分供式能量系统进行了比较,得出楼宇冷热电联供系统的节能性。研究结果表明,系统余热利用情况和主要设备运行效率是影响楼宇冷热电联供系统节能性的主要因素,系统方案选择应兼顾考虑应用场合冷、热、电负荷需求比例情况。     

冷热电三联供系统的优化研究

冷热电联供系统主要应用于大型集中性供能系统中。作为分布式能源的一种,冷热电联供系统具有节约能源、改善环境、提高电力综合效益的优势。一般情况下,三联供系统是以天然气为燃料带动燃气轮机、微燃机或内燃机发电机等燃气发电设备运行,产生的电力供应用户的电力需求,系统发电后排出的余热通过余热回收利用设备(余热锅炉或者余热直燃机等)向用户供热、供冷。通过这种方式提高整个系统的一次能源利用率,实现能源的梯级利用,还可以提供并网电力作能源互补,经济收益和效率均得以提升。研究较为常见的燃气轮机中的一种蒸汽型吸收式冷热电联产系统,对不同配置方式和运行方式进行横向与纵向交叉比较,以完成系统优化研究。     

微型燃气轮机冷热电联供系统变工况性能研究

设计了以微型燃气轮机为核心的冷热电联供系统并建立了该系统变工况性能分析模型.结合具体算例,对该联供系统在采用"以冷(热)定电"的模式下运行变工况时的热力性能进行了计算分析,揭示了系统在不同调节方式下的变工况性能.结果表明,回热度调节具有较宽的冷热负荷调节范围,因此微型燃气轮机联供系统特别适用于冷热负荷变化大而系统内电负荷较稳定的场合.为使系统变工况时保持较高的性能,当冷热负荷增加时应优先考虑发电功率调节,其次采用回热度调节,最后采取补燃量调节;当冷热负荷减小时宜采用相反的调节顺序.研究结果将对微型燃气轮机冷热电联供系统的设计及运行提供有益的参考和指导.     

多能耦合的冷热电联供系统策略分析和优化设计

建立了光伏、光热和天然气耦合利用的冷热电联供系统,研究了系统运行策略、燃气轮机控制策略和太阳能利用策略对系统总体性能的影响规律,并综合考虑经济性、节能性、环保性的系统性能评价指标,优化了系统容量配置和运行参数。研究表明:系统在热跟随、燃气轮机变负荷运行、太阳能光伏光热一体化利用条件下总体性能最优;特定用户负荷下,系统存在最优设备容量和电制冷比,在热跟随模式下最优开关系数值比较小,避免了频繁启停。     

基于燃气轮机的冷热电联供系统优化配置研究

根据燃气轮机冷热电联供系统的优化配置步骤,对燃气轮机冷热电联供系统的几种方案进行研究,确立了以年总费用、一次能耗量、二氧化碳排放量的多目标函数模型和约束条件,并确定各目标函数的权重。在建筑物满足冷热电负荷的情况下,采用混沌粒子群算法对几种方案进行优化,得出适合该建筑物的最优方案,确立了最优方案中各设备的运行台数,并对其运行策略进行分析。     

天然气冷热电联供系统在某商场建筑中的应用分析

简要介绍天然气冷热电联供系统的国内外研究动态,从系统的优化配置、运行策略和性能分析几个方面列举一些对该领域有突出贡献的专家学者及其研究成果。针对一个典型的商场建筑冷热电联供系统进行性能分析,并将其与传统的供能方式进行了比较。     

微型燃气轮机与冷热电联供系统

介绍了微型燃气轮机和溴化锂吸收式冷温水机组直接组成的冷热电联供系统,根据微型燃气轮机的回热器的特性,对系统进行了简要的分类,指出了其利用特点,论述了微型燃气轮机冷热电联供系统在能源利用中的优势。     

内燃机分布式供能系统发展现状及案例研究

针对使用内燃机作为原动机的分布式供能系统进行研究,对该技术在国内外的研究进展、应用情况进行综述,对比了3种在不同负荷要求下,结合不同余热回收方式的内燃机分布式系统。并将内燃机与燃气轮机2种天然气分布式原动机进行对比,前者发电效率更高、初期投资更少,适合应用于5 MW以下规模的分布式系统中。以上海某分布式项目为例,对具体的内燃机分布式冷热电联供系统组成、技术参数进行介绍,并通过计算三联供系统一次能源节约率对其节能效果进行计算分析。结果表明:该分布式联产系统夏季典型工况能耗为分产系统的65.41%,冬季为56.58%,节能效果明显。     

微燃机冷热电联供系统性能的模拟研究

介绍了冷热电联供(CCHP)系统,以上海某示范性微燃机冷热电联供系统为研究对象,通过建立系统主要设备的数学模型,模拟分析了系统在不同环境温度下的性能和系统全年的运行工况。结果表明:微燃机冷热电联供系统的性能受环境温度的影响,系统过渡季节不运行时年平均能源综合利用率可达到70%以上。     

Optimal design and 4E assessment of typical combined cooling,heating and power systems considering the effects of energy price fluctuation

Although as an advanced energy utilization approach, the performance of combined cooling, heating, and power (CCHP) system is susceptible to its configuration and operation strategy. Energy price will also affect the system performance indirectly by influencing the system's design scheme. In this paper, a linear programming (LP) based optimization model is formulated to obtain the optimal design scheme that minimizes the annual total cost of typical CCHP systems, and a comprehensive assessment framework involving economic, energy, exergy, and ecological (4E) aspects is established to assess the system performance roundly. Taking a CCHP project in Xian, China as the specific case, the design and assessment of the CCHP system are completed and sensitivity analyses for two steps, namely configuration design step and operation strategy design step, are carried out to explore the impacts of energy price fluctuation on the design scheme and performance of the system. In this process, the coupling relationship between the purchase price of natural gas and electricity are considered, and as a special form of energy price, the effects of the feed‐in tariff are also discussed. The results show that the performance of the CCHP system is superior to the separate generation (SG) system in 4E aspects, reducing the running and maintenance cost, primary energy consumption, and greenhouse gas emissions by 18.63%, 24.77%, and 31.88%, respectively, and promoting the exergy efficiency by 30.87%. The feed‐in tariff lower than or equal to the electricity price will have positive effects on the overall performance of the CCHP system, and a lower natural gas price and a higher electricity price are benefit for playing the advantages of the system.     

Thermodynamic analysis of a new combined cooling, heat and power system driven by solid oxide fuel cell based on ammonia-water mixture

Although a solid oxide fuel cell combined with a gas turbine (SOFC-GT) has good performance, the temperature of exhaust from gas turbine is still relatively high. In order to recover the waste heat of exhaust from the SOFC-GT to enhance energy conversion efficiency as well as to reduce the emissions of greenhouse gases and pollutants, in this study a new combined cooling, heat and power (CCHP) system driven by the SOFC is proposed to perform the trigeneration by using ammonia-water mixture to recover the waste heat of exhaust from the SOFC-GT. The CCHP system, whose main fuel is methane, can generate electricity, cooling effect and heat effect simultaneously. The overall system performance has been evaluated by mathematical models and thermodynamic laws. A parametric analysis is also conducted to examine the effects of some key thermodynamic parameters on the system performance. Results indicate that the overall energy conversion efficiency exceeds 80% under the given conditions, and it is also found that the increasing the fuel flow rate can improve overall energy conversion efficiency, even though both the SOFC efficiency and electricity efficiency decrease. Moreover, with an increased compressor pressure ratio, the SOFC efficiency, electricity efficiency and overall energy conversion efficiency all increase. Ammonia concentration and pressure entering ammonia-water turbine can also affect the CCHP system performance.     

Performance comparison of combined cooling heating and power system in different operation modes

Operation mode of combined cooling heating and power (CCHP) system determines its energetic and environmental performances. This paper analyzes the energy flows of CCHP system and separated production (SP) system. The fuel energy consumptions of CCHP system following electrical demand management (EDM) and thermal demand management (TDM) are deduced respectively. Three indicators: primary energy saving, exergy efficiency and CO₂ emission reduction, are employed to evaluate the performances of CCHP system for a commercial building in Beijing, China. The feasibility analysis shows that the performance of CCHP system is strictly dependent upon building energy demands. The selection of CCHP operation modes is systemically based on building loads, CCHP system and local SP system. The calculation results conclude that CCHP system in winter under EDM achieves more benefits than in summer. The sensitivity discussion indicates that the coefficient of performance for cooling and the efficiency of electricity generation are the most sensitive variables to the energetic and environmental performances of CCHP system.     

基于燃气轮机循环的冷热电联产系统对比分析

本文以燃气轮机作为发电装置,分别采用简单循环与回热循环,提出天然气冷热电联产系统两套方案.利用数值分析方法,对比分析各方案的系统效率与经济性指标.分析表明:基于回热循环的燃气轮机联产系统在经济效益和能源利用效率方面,相比简单循环联产系统都有十分明显的优势.     

Thermodynamic and economic assessment of a PEMFC-based micro-CCHP system integrated with geothermal-assisted methanol reforming

A micro-combined cooling heating and power (CCHP) system integrated with geothermal-assisted methanol reforming and incorporating a proton exchange membrane fuel cell (PEMFC) stack is presented. The novel CCHP system consists of a geothermal-based methanol steam reforming subsystem, PEMFC, micro gas turbine and lithium bromide (LiBr) absorption chiller. Geothermal energy is used as a heat source to drive methanol steam reforming to produce hydrogen. The unreacted methanol and hydrogen are efficiently utilized via the gas turbine and PEMFC to generate electricity, respectively. For thermodynamic and economic analysis, the effects of the thermodynamic parameters (geothermal temperature and molar ratio of water to methanol) and economic factors (such as methanol price, hydrogen price and service life) on the proposed system performance are investigated. The results indicate that the ExUF (exergy utilization factor the exergy utilization factor), TPES (trigeneration primary energy saving) and energy efficiency of the novel system can be reached at 8.8%, 47.24% and 66.3%, respectively; the levelized cost of energy is 0.0422 $/kWh, and the annual total cost saving ratio can be reached at 20.9%, compared with the conventional system. The novel system achieves thermodynamic and economic potential, and provides an alternative and promising way for efficiently utilizing abundant geothermal energy and methanol resources.     

A linear programming optimization model for optimal operation strategy design and sizing of the CCHP systems

Combined cooling, heat, and power (CCHP) system offers numerous potential advantages for the supply of energy to residential buildings in the sense of improved energy efficiency and reduced environmental burdens. To realize the potential for being more beneficial, however, such systems must reduce total costs relative to conventional systems. In this study, a linear programming optimization model was presented for optimum planning and sizing of CCHP systems. The purpose of the model is to give the design of the CCHP system by considering electrical chiller and absorption chiller simultaneously in economic viewpoint. A numerical study was conducted in Tehran to evaluate the CCHP system model. The linear programming (LP) model determines the optimal sizes of the CCHP equipment by considering capital cost of the system. It showed that by considering electricity buyback, the optimum size of the electrical chiller decrease and the optimum size of the combined heat and power (CHP) unit and the absorption chiller increase dramatically with respect to without electricity buyback. Also, the LP model determines the optimal operation strategy of the system by neglecting capital cost. The optimally operated CCHP system encompassing electrical and absorption chiller could result in an 18% decrease in operating cost when compared to a CHP system encompassing electrical chiller only. Without electricity buyback, the profitability of CCHP was 23%, while with electricity buyback, profitability became 39%. Furthermore, a sensitivity analysis was conducted to show how the important parameters affect the entire system performance.     

DES/CCHP系统和区域能源利用效率计算方法及影响因素分析

天然气分布式冷热电联供(DES/CCHP)是中国“十二五”期间提高能效、保障经济发展的重要战略举措,其评价指标是能源利用效率、经济效益、碳排放.DES/CCHP实现高效的技术关键包括:把所有终端用能集成为一个“总能源系统”;科学用能,核心是尽可能减小每一级用能的(火用)损耗;尽可能安排多个冷、热、电、汽终端用户时空分布的最优组合;需要较大的系统规模.新区DES/CCHP系统能效是决定区域总能效的最主要因素,两者的区别在于交通用能、其他用能和外来电力,可在取得相应数据基础上计算得出.计算能源利用效率的一般公式是:能效=终端耗用各种能源总量之和/耗用的一次能源总量,CCHP能效计算的分子必须是全部终端用能,必须按照8650h/a不同负荷逐时累加求和计算,不能取设计工况数据;分母必须全部折算成一次能源.在计算出区域规划的能效、总能耗和一次能源构成后,便可按照规划目标年度的GDP数据,推算出能源强度、碳强度和二氧化碳排放量等低碳发展指标.影响区域能源利用效率的因素包括外部因素——天然气价格与上网电价,客观因素——产业格局、气候条件和实际进展与规划格局的差异,以及主观因素等,其中外部、客观因素是决定能效的硬性约束.     

The effect of an energy storage unit on the performance micro CCHP systems

分布式冷热电联供系统作为传统分布式供能系统的延伸,在继承传统系统能量分级利用优点的同时,其供能效率和经济性都有很大的提升。为保证系统冷、热、电负荷按照既定的规律变化,维持能量的输出与负荷需求相匹配,确保较高的运行效率,创新地加入储能子系统。本文通过定性分析的方法,针对储能子系统在分布式冷热电联供系统中的作用展开讨论,结合微型冷热电联供系统的模拟结果,对储能子系统进行初步的设计和计算,证明储能子系统的加入对分布式冷热电联供系统的效率和稳定性均有提升。     

Evaluation of energy saving of CCHP systems using an active energy storage regulation method

节能性是评价冷热电联供系统的重要指标之一.阐述了分布式冷热电联供系统中主动储能调控方法的原理.基于用户侧负荷特性和燃气轮机变工况运行规律的分析,采用相对节能率作为评价联供系统节能性的指标,以夏季冷电并供时的饭店类型建筑典型负荷为案例,探讨主动储能调控在分布式冷热电联供系统中的节能效果及影响因素.结果表明,与常规分产系统相比,无主动储能的相对节能率为11.8%,主动储能调控的联供系统相对节能率为21.6%.相对节能率的大小受到电压缩制冷系统性能系数和用户负荷冷电比的影响,电压缩制冷系统性能系数越高则联供系统相对节能率越低,用户负荷冷电比越高,联供系统相对节能率越高.     

内燃机冷热电联产系统设计点性能分析

简介内燃机冷热电联产系统的发展现状,总结了发电用内燃机在设计点工况下主要参数的现有分布范围:排气温度约为450~600℃,排气流量基本上与额定功率呈线性关系,发电效率一般在33%~45%。对联产系统不同形式的能量输出、联产系统经济效率等进行分析研究,表明联产系统回收的能量主要来自排气和冷却水,排气回收能量一般高于冷却水回收能量。与热电联产系统相比,由于制冷比供热困难,冷热电联产系统的经济效率较高。