冷热电三联供系统配置与运行策略的优化

对一个冷热电三联供系统的配置与运行策略进行了分析。该系统由燃气内燃机、吸附制冷机和电热泵组成。根据设备容量、数量、性能和分时段能源价格等，在满足应用场合冷热电负荷需求条件下，运用混合整型（0-1）多级目标规划方法，建立了联供系统的优化模型，得到了系统的最优配置和运行策略。该模型三级目标函数包括运行费用最低、各主要设备配置数量最少和实际运行负荷率最大化。应用该模型对一实例进行的分析取得了较好的经济效果。     

Optimization design of BCHP system to maximize to save energy and reduce environmental impact

The energetic and environmental performances of building cooling heating and power (BCHP) system are closely dependent on its design and operation strategy. This paper analyzes the energy consumptions of a conventional separation production (SP) system and a BCHP system respectively and constructs their corresponding environmental impact models. Furthermore, three energy-related environmental issues, global warming, acid precipitation and stratospheric ozone depletion, are assessed in the proposed emission model. To maximize the benefits (energy-saving and emission-reducing) achieved by the BCHP system in comparison to the SP system, genetic algorithm (GA) is employed to optimize the capacity of BCHP system in consideration of its operation mode. A numerical case of BCHP system for a hotel building is applied to ascertain the effectiveness of the optimal method and demonstrate the performances of the optimal BCHP system.     

Sensitivity analysis of optimal model on building cooling heating and power system

The optimization of building cooling heating and power (BCHP) system is helpful to improve its comprehensive performance including energetic, economic and environmental aspects. However, the optimal results are closely dependent on the initial setting parameters. This paper deduces the energy consumption of BCHP system following the electrical load and presents the optimization problem of BCHP system that includes the decision variables, the objective function, the constraint conditions and the solution method. The influences of the initial parameters, which include the technical, economic and environmental parameters, the building loads and the optimization setting parameters, on the optimal decision variables and the performances of BCHP system are analyzed and compared. The contour curves of the performances of BCHP system in comparison to the conventional separation production (SP) system, and the sensitivity of the optimal decision variables to the initial parameters are obtained.     

联合循环热电冷三联供系统的热经济性分析

燃气—蒸汽联合循环的热电冷三联供系统是一种崭新的能量供应系统,它实现了能量的梯级利用。本文在联合循环的热电冷三联供系统基础上,从总热效率、效率和经济效率三个方面并结合具体实例对系统进行了热经济性计算和分析。     

Multi-criteria analysis of combined cooling,heating and power systems in different climate zones in China

The design and operation of combined cooling, heating and power (CCHP) systems are greatly dependent upon the seasonal atmospheric conditions, which determine thermal and power demands of buildings. This paper presents a mathematical analysis of CCHP system in comparison to separate system. The corresponding primary energy consumption in thermal demand management (TDM) and electrical demand management (EDM) operation modes are deduced. Three relative criteria, primary energy saving (PES), CO₂ emission reduction (CO₂ER), and annual total cost saving (ATCS) are employed to evaluate the respective performances of CCHP systems for a hypothetical building in five different climate zones from the technical, environmental and economic aspects. The results indicate that CCHP system in TDM mode in the cold area, where the building requires more heating during the year, achieves more benefit over separate system while CCHP system in EDM mode suits the building having stable thermal demand in mild climate zone.     

天然气热电冷联产的技术方案分析

天然气热电冷联产(CCHP)由于其较高的能源利用率，在全世界范围内得到了迅速的发展和广泛的利用。目前国内外相关设备已经比较成熟，因而热、电、冷相关技术参数的匹配便成为该总能系统中的技术关键，并在很大程度上影响到系统的经济效益。介绍了天然气热电冷联产系统的基本概念及发展应用情况，然后以国内某工厂CCHP系统的设计为实例，对“以热定电”和“以电定热”两种技术方案进行了参数计算和方案比较，并确定了“以电定热”的推荐方案。     

燃气轮机和内燃机在天然气冷热电联供系统中的性能比较

天然气冷热电联供系统中驱动装置的选型对系统的运行性能至关重要.在这一背景下,分析比较了燃气轮机和内燃机在冷热电联供系统中的发电效率、热效率、一次能源利用率等性能指标以及对环境的影响,并以北京市某宾馆为例设计了天然气冷热电联供系统方案,在余电可上网出售的条件下,利用RETScreen软件分别比较了天然气价和电价对燃气轮机系统和内燃机系统运行利润的影响.     

热电冷联产系统的热经济性分析

从能分析和火用分析两方面对热电冷联产系统的热经济性进行计算和分析,采用等效发电效率、等效发电火用效率与发电煤耗三种评价方法,以找出能量利用的薄弱环节,提高能源利用效率。     

Energy management strategy and capacity optimization for CCHP system integrated with electric-thermal hybrid energy storage system

In order to improve the comprehensive energy utilization rate of combined cooling, heating, and power (CCHP) system, a hybrid energy storage system (HESS) is proposed in this paper consisting of electric and thermal energy storage systems. And the overall optimization design and operation of CCHP system with HESS are the main problems to be solved in application. Therefore, the topology and the energy flow model of CCHP system with HESS are established and analyzed according to the energy conversion characteristics of the component equipment. Moreover, combined with five evaluative restrictions for HESS system, a rule-based energy management strategy is designed to realize the decoupling regulation of electric energy and thermal energy in CCHP system. On this basis, a multi-objective optimization model is studied by taking the indicators of annual cost ratio, the primary energy consumption ratio, and loss energy ratio, and then the capacity parameters are optimized by particle swarm optimization algorithm (PSOA). Finally, a case is carried out to compare the energy allocation situations and capacity optimization results between CCHP system with HESS and CCHP system with single thermal energy storage system (ST). Results show that the capacity of ICE is reduced by 34%, and the annual cost and the primary energy consumption are saved about 7.69% and 18.47%, respectively, demonstrating that HESS has better optimization effect and applicable for small-scale CCHP system.     

Optimizing circuit parameters of the biohydrogen real-time power generating system by genetic algorithm

This study performs optimal estimation of circuit parameters for a biohydrogen real-time power generating system by using a penalty-function genetic algorithm (GA). Circuit parameters of this system change with operating temperature and current density; some circuit parameters are nonlinear. To elucidate the circuit characteristics of the whole system, this study uses penalty-function GA to optimally estimate circuit parameters using data from a V–I$V–I$ characteristic experiment on novel biohydrogen real-time power generating system. This study then solves the circuit characteristic by the estimated circuit parameters formulated utilizing Kirchhoff's law. Then, the estimated V–I$V–I$ characteristic is then compared with actual measurements to verify the feasibility of this novel approach. In the same manner, the capacitor parameter of the biohydrogen real-time power generating system can be estimated to identify the alternating current (AC) equivalent circuit for this system.     

分布式冷热电联产系统的能量梯级利用率新准则

分布式冷热电联产系统评价准则对系统集成开拓与设计优化至关重要,传统的热效率、火用效率等难以全面科学地评估多供能系统性能特性,也不适于作为联产系统设计优化的目标函数。文章概述了目前常用的评价准则及其存在问题,基于热力学基本方程和联产系统的本质特征,提出了能量梯级利用率的评价准则。新准则从发电、制冷及供热等过程耗用能量的品位和生产产品的品质等来全面权衡不同能量转换利用过程的本质差异,并借助权重系数来综合量化描述。还结合实际的联产系统算例,对新准则和原有的评价准则进行比较分析。研究表明,该准则应用简便、合理、准确,为冷热电联产系统集成开拓与设计优化提供了一个更好的新准则。     

小型燃气轮机CCHP系统变工况性能入口加热调控研究

提出了一种利用冷热电联产系统(CCHP)低温烟气与环境空气混和加热控制压气机入口温度,提升燃气轮机冷热电系统变工况性能的方法,并以1.9 MW小型燃气轮机OPRA16为例,建立了CCHP系统模型,分析了调控方法的效果、机理。结果表明,入口混和加热可以有效改善冷热电联产系统变工况下系统性能,并扩展系统节能运行范围。与传统燃料流量调控方法相比,新型调控手段下夏季制冷与冬季供热模式下系统节能率分别提升5.7%和21.6%。     

机组负荷优化分配的改进遗传算法

研究了遗传算法在机组负荷优化分配中的应用。针对简单遗传算法的缺点．根据具体问题的特征,对算法进行了改进,避免了在遗传操作过程中产生不可行解,提高了搜索效率。算例证明了该方法是正确和有效的。     

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。     

企业冷热电联产系统的多周期优化运行

以蒸汽动力系统为研究对象,建立一个综合考虑设备启停费用、折旧维护费用以及设备模型的合理线性化的混合整数线性模型,利用优化软件LINGO,应用实例得到了冷热电联产系统在不同周期内的最优的计划调度方案,求解出不同周期内的最小运行费用,节省大量运行成本。     

Investigation on performance of an integrated solid oxide fuel cell and absorption chiller tri-generation system

An integrated tri-generation system incorporating a solid oxide fuel cell (SOFC) and a double-effect water/Lithium Bromide absorption chiller is presented in this paper. The proposed tri-generation system can provide power, cooling or heating simultaneously with a typical gas produced from a gasication process. The system conguration and design are discussed, and the energy and mass balances are obtained through the matrix representation method and integrated into a simulation program by MATLAB soft package. The developed model comprises of three modules: SOFC module, exhaust combusting and HRSG module, and the absorption chiller module. Validation of the SOFC model is performed by comparison with a single tubular cell of Siemens-Westinghouse, and a specific case study of the system is presented. For parametric analysis, the fuel utilization ratio, fuel flow ratio and air inlet temperature are investigated and the results are discussed in detail.     

Optimization for a steam turbine stage efficiency using a genetic algorithm

Based on the genetic optimization theory, a design method for the flow path of an axial flow steam turbine stage is presented. In this method the maximum efficiency of the stage is taken as the objective, a series of functions are taken as constraints, and the optimal geometric and aerodynamic parameters are solved using the genetic algorithm process. The efficiency and constraints evaluation are performed using a program for the thermodynamic calculation of steam turbine stages in the design condition. The fitness of each individual is determined by the turbine efficiency and a penalty function containing the constraints. The proposed method is applied to the design of a real steam turbine stage. The results show that the new method successfully reveals the optimal geometric and aerodynamic parameters of the stage for maximum efficiency.     

Theoretical research of a silica gel–water adsorption chiller in a micro combined cooling,heating and power (CCHP) system

A novel micro CCHP system, which is based on a two bed silica gel–water adsorption chiller, is constructed in this work. To reveal the chiller characteristic in this system, a transient model of the adsorption chiller is developed. According to the comparison of the simulated results and experimental data, the presented model shows a good performance in predicting the chiller performance, with both stable and variable heat source temperature. With the analysis of simulated results, it is found that the cooling capacity and the coefficient of performance (COP) of the chiller are influenced significantly by the average value and variation rate of electric load, as well as the average value of cooling load. The water tank also shows a great effect on the chiller performance. To get better performance of the chiller, the water tank should be adopted when the electric load is low or its variation rate is positive, and should not be utilized when the electric load is high or its variation rate is negative. A 500 L water tank is recommended in order to get better performance and acceptable start-up time. Furthermore, to get better performance as well as higher security, a cold accumulator should be adopted.     

An accurate method for the PV model identification based on a genetic algorithm and the interior-point method

Due to the PV module simulation requirements as well as recent applications of model-based controllers, the accurate photovoltaic (PV) model identification method is becoming essential to reduce the PV power losses effectively. The classical PV model identification methods use the manufacturers provided maximum power point (MPP) at the standard test condition (STC). However, the nominal operating cell temperature (NOCT) is the more practical condition and it is shown that the extracted model is not well suited to it. The proposed method in this paper estimates an accurate equivalent electrical circuit for the PV modules using both the STC and NOCT information provided by manufacturers. A multi-objective global optimization problem is formulated using only the main equation of the PV module at these two conditions that restrains the errors due to employing the experimental temperature coefficients. A novel combination of a genetic algorithm (GA) and the interior-point method (IPM) allows the proposed method to be fast and accurate regardless the PV technology. It is shown that the overall error, which is defined by the sum of the MPP errors of both the STC and the NOCT conditions, is improved by a factor between 5.1% and 31% depending on the PV technology.     

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.