带压缩空气储能的冷热电联产系统的(火用)分析

对一种带压缩空气储能的冷热电联产系统进行了热力学[火用]分析，得到了各主要部件和整个系统的[火用]损失及[火用]效率的变化规律。分析结果表明：空气透平绝热效率的提高对系统[火用]效率的贡献大于压缩机效率同样提高的功效；在其它参数确定时，存在最佳压比，可使系统的[火用]效率在该条件下达极值；高温换热器是新型冷热电联产系统中产生[火用]损失的主要部件，而循环水量的大小是影响高温换热器[火用]效率的主要因素。     

实际回热式布雷顿热电联产装置的火用经济性能——I.循环模型与参数分析

应用有限时间热力学方法,研究了恒温热源条件下实际回热式布雷顿热电联产装置的火用经济性能,导出了利润率及火用效率解析式.利用数值计算方法,分析了各种设计参数对联产装置性能的影响.     

开式回热燃气轮机热电冷联产装置性能优化

建立了考虑压降的开式回热燃气轮机热电冷联产装置的有限时间热力学模型,导出了各个部件的相对压降和各个热流率与压气机进口相对压降的关系式,以第一定律效率、[火用]输出率、[火用]效率和利润率为目标,在无燃料消耗和装置尺寸约束下,通过数值计算发现分别存在最佳的压气机进口相对压降使[火用]输出率和利润率取得最优值,进一步优化压比,得到了最大[火用]输出率和利润率,分别存在最佳的供热温度使最大[火用]输出率和利润率取得双重最大值,以利润率为设计目标能够减小装置的尺寸.在燃料消耗和装置尺寸约束下,优化了压气机进口相对压降,得到了最优效率,同时各部件流通面积分配也得到了优化.回热能够增大装置的利润率和效率.     

实际回热式布雷顿热电联产装置的火用经济性能-Ⅱ．热导率分配与压比优化

应用有限时间热力学方法,研究了恒温热源条件下实际回热式布雷顿热电联产装置的火用经济性能,导出了利润率及烟效率解析式。利用数值计算方法,以利润率为目标,对热导率的分配和压比的选取进行了优化,研究了最优利润率及相应火用效率特性,并分析了各种联产设计参数对联产优化性能的影响。     

HAT循环饱和器工质[火用]计算分析及[火用]效率

饱和器是HAT循环中的关键部件，对其性能的认识关系到整个系统的性能分析。运用[火用]的方法，计算了饱和器工质湿空气和水的堋值，分析了不同参考点的温度和湿度对[火用]值的影响规律，以及物理[火用]和化学扩散[火用]随湿空气温度的变化情况。通过建立饱和器[火用]平衡模型，采用了目的[火用]效率作为饱和器[火用]效率。计算结果表明：湿空气[火用]值随参考点的温度和湿度变化规律为：先减小，直到最低点为零，然后不断增加，[火用]值始终大于（等于）零，并且与参考点参数差距越大，[火用]值越大。当湿空气温度增加，物理[火用]所占比重减少，而化学扩散[火用]的比重增加，在到达一定温度后，化学[火用]大于物理[火用]。     

武汉石油化工厂热电联产及其(火用)分析评价

引入热电联产及[火用]的概念,应用[火用]分析法对热力系统进行评价,客观真实地反映出系统及热力设备的热能利用水平,并指出热能利用和热电联产的原则和系统经济运行方式,真正实现热电经济运行。     

不可逆闭式布雷顿热电联产装置火用经济性能优化

应用有限时间热力学方法,研究了恒温热源条件下不可逆闭式布雷顿联产装置的火用经济性能,导出了利润率及火用效率解析式.利用数值计算方法,以利润率为目标,对热导率分配和压比的选取进行了优化.研究了最优利润率及相应火用效率特性,并分析了各种联产设计参数对联产优化性能的影响.结果表明,对于给定的总热导率,在高温、低温和用户侧换热器之间,存在唯一的最佳热导率分配比和唯一的最佳压比,使得装置的无因次利润率取得最大值;同时存在最佳用户温度.     

高炉余能余热驱动的内可逆闭式布雷顿热电冷联产装置火用经济性能分析

用有限时间热力学理论研究恒温热源条件下由一个内可逆闭式布雷顿热机循环和一个内可逆四热源吸收式制冷循环组成的高炉余能余热驱动的热电冷联产装置的火用经济性能,导出热电冷联产装置的利润率和火用效率与压气机压比的关系。利用数值计算,分析热电比和吸收式制冷循环总放热量在吸收器和冷凝器之间的分配率对利润率与火用效率关系的影响,并研究联产装置各种参数对最大利润率及相应火用效率特性的影响。     

高炉余能余热驱动的不可逆闭式布雷顿热电冷联产装置火用性能分析

用有限时间热力学理论建立了由一个高炉余能余热驱动的不可逆闭式布雷顿循环和一个内可逆四热源吸收式制冷循环组成的热电冷联产循环模型,导出了其火用输出率和火用效率的表达式。利用数值计算方法,分析了循环各参数对火用输出率和火用效率与压比关系的影响,比较了最大火用输出率和最大火用效率性能,给出了实际热电冷联产装置设计和运行的建议。     

中冷回热布雷顿热电联产装置的火用性能分析

建立了恒温热源内可逆中冷回热布雷顿热电联产装置模型,基于火用分析的观点,用有限时间热力学理论和方法研究了装置的性能,导出了无量纲火用输出率和火用效率的解析式。讨论了总压比给定和总压比变化两种情形,优化了中间压比和总压比,通过数值计算分析了回热度、中冷度和高温侧热源温度与环境温度之比等参数对装置一般性能和最优性能的影响,研究了火用输出率和火用效率之间的关系,其特性关系为扭叶型。最后发现分别存在最佳的用户侧温度使火用输出率和火用效率取得双重最大值。     

Parametric analysis of a solar energy based multigeneration plant with SOFC for hydrogen generation

Renewable energy-based hydrogen production plants can offer potential solutions to both ensuring sustainability in energy generation systems and designing environmentally friendly systems. In this combined work, a novel solar energy supported plant is proposed that can generate hydrogen, electricity, heating, cooling and hot water. With the suggested integrated plant, the potential of solar energy usage is increased for energy generation systems. The modeled integrated system generally consists of the solar power cycle, solid oxide fuel cell plant, gas turbine process, supercritical power plant, organic Rankine cycle, cooling cycle, hydrogen production and liquefaction plant, and hot water production sub-system. To conduct a comprehensive thermodynamic performance analysis of the suggested plant, the combined plant is modeled according to thermodynamic equilibrium equations. A performance assessment is also conducted to evaluate the impact of several plant indicators on performance characteristics of integrated system and its sub-parts. Hydrogen production rate in the suggested plant according to the performance analysis performed is realized as 0.0642 kg/s. While maximum exergy destruction rate is seen in the solar power plant with 8279 kW, the cooling plant has the lowest exergy destruction rate as 1098 kW. Also, the highest power generation is obtained from gas turbine cycle with 7053 kW. In addition, energetic and exergetic efficiencies of solar power based combined cycle are found as 56.48% and 54.06%, respectively.     

火电厂热力系统Yong分析

应用Yong分析方法，对火电厂热力系统进行了诊断。分析了系统中各主要设备和环节的热力学完善性，找出系统中的薄弱环节，并与使用传统的热平衡法取得的结果进行了比较，为火电厂的运行优化和节能技改提供了较为科学的依据。     

Performance analysis of the power conversion unit of a solar chimney power plant

The power conversion unit (PCU) of a large solar chimney power plant consists of one or several turbogenerators, power electronics, a grid interface and the flow passage from collector exit to chimney inlet. The main goals of this paper are to analyze the performance of the PCU and its interaction with the plant as well as to compare three configurations from an efficiency and energy yield point of view.First, a reference plant is defined and the plant performance data taken from simulations with a model found in the literature are analyzed, and the matching of the turbine(s) to the characteristic of the plant is discussed. It was found that a well designed turbine can be run at high efficiency over the entire operating range, as the plant performance data can be fitted using the ellipse law of Stodola.Loss models for all components of the power conversion unit are then defined, and the impact of the various losses on the overall performance is assessed. Three configurations of the PCU are compared, i.e. the single vertical axis, the multiple vertical axis and the multiple horizontal axis turbine configuration. It is found that the single vertical axis turbine has a slight advantage with regards to efficiency and energy yield because certain loss mechanisms are not present. But its output torque is tremendous, making its feasibility questionable. It is shown that with designing the flow passage in an appropriate manner the aerodynamic losses can be kept low. The assumption made by many other researchers that the total-to-total efficiency of the PCU is 80 % has been confirmed with the present model. Further, it has been shown that the PCU efficiency deteriorates significantly with increasing diffuser area ratio but improves only slightly with reducing the diffuser area ratio below unity.     

Performance analysis of a 3 kW grid-connected photovoltaic plant

In this paper, the grid-connected photovoltaic plant of the University of Calabria is presented. The photovoltaic plant has a peak power of 2.7 kW, and has been projected and built near the Building Energy Research Laboratory of the Department of Mechanical Engineering at the University of Calabria.The plant is suitably monitored for the experimental validation of the models and of the simulation codes that allow the evaluation of the performance of the single components and of the overall plant. In this paper, some experimental results of the efficiencies of the photovoltaic field and of the inverter are presented, as well as other plant data.     

Transient analysis of integrated Shiraz hybrid solar thermal power plant

Shiraz solar thermal power plant is designed for 250 kW power supply during available sun radiation. It is decided to promote the field of collectors by installing a large parabolic collector and combining the system with a 500 kW hybrid boiler. For the new integrated configuration, thermodynamic analysis is required for engineering design and evaluating thermal performance.For the new system, transient simulation is performed under different working conditions. In the plant, each component is simulated transiently, by considering initial condition and capacity rate of the component as well as all the connecting pipes and instruments. Results of the simulation for thermal performance are compared with field experimental measurements for several periods. Taking into account the thermodynamic concepts and the results of numerical and experimental analysis, the best operation strategies are selected for optimum performance and control philosophy based on the new integrated collector.     

Exergy analysis of a dual-level binary geothermal power plant

Exergy analysis of a 12.4 MW existing binary geothermal power plant is performed using actual plant data to assess the plant performance and pinpoint sites of primary exergy destruction. Exergy destruction throughout the plant is quantified and illustrated using an exergy flow diagram, and compared to the energy flow diagram. The causes of exergy destruction in the plant include the exergy of the working fluid lost in the condenser, the exergy of the brine reinjected, the turbine-pump losses, and the preheater–vaporizer losses. The exergy destruction at these sites accounts for 22.6, 14.8, 13.9, and 13.0% of the total exergy input to the plant, respectively. Exergetic efficiencies of major plant components are determined in an attempt to assess their individual performances. The exergetic efficiency of the plant is determined to be 29.1% based on the exergy of the geothermal fluid at the vaporizer inlet, and 34.2% based on the exergy drop of the brine across the vaporizer–preheater system (i.e. exergy input to the Rankine cycle). For comparison, the corresponding thermal efficiencies for the plant are calculated to be 5.8 and 8.9%, respectively.     

Parametric analysis of a coal based combined cycle power plant

In the present paper thermodynamic analyses, i.e. both energy and exergy analyses have been conducted for a coal based combined cycle power plant, which consists of pressurized circulating fluidized bed (PCFB) partial gasification unit and an atmospheric circulating fluidized bed (ACFB) char combustion unit. Dual pressure steam cycle is considered for the bottoming cycle to reduce irreversibilities during heat transfer from gas to water/steam. The effect of operating variables such as pressure ratio, gas turbine inlet temperature on the performance of combined cycle power plant has been investigated. The pressure ratio and maximum temperature (gas turbine inlet temperature) are identified as the dominant parameters having impact on the combined cycle plant performance. The work output of the topping cycle is found to increase with pressure ratio, while for the bottoming cycle it decreases. However, for the same gas turbine inlet temperature the overall work output of the combined cycle plant increases up to a certain pressure ratio, and thereafter not much increase is observed. The entropy generation, the irreversibilities in each component of the combined cycle and the exergy destruction/losses are also estimated. Copyright © 2005 John Wiley & Sons, Ltd.     

On the exergy analysis of power plants

The thermal performance of power generating and consuming devices can be improved significantly, both during design and operation. This is especially important in eastern and central European countries during their transition to a market environment. A solution can be sought by combining exergy and economic analyses. The performances of conventional power plants and nuclear power plants are discussed, based on the exergy concept. It is proposed to define the entire nuclear plant efficiency by the system coefficient of performance.     

Comparative performance analysis of cogeneration gas turbine cycle for different blade cooling means

The paper compares the thermodynamic performance of MS9001 gas turbine based cogeneration cycle having a two-pressure heat recovery steam generator (HRSG) for different blade cooling means. The HRSG has a steam drum generating steam to meet coolant requirement, and a second steam drum generates steam for process heating. Gas turbine stage cooling uses open loop cooling or closed loop cooling schemes. Internal convection cooling, film cooling and transpiration cooling techniques employing steam or air as coolants are considered for the performance evaluation of the cycle. Cogeneration cycle performance is evaluated using coolant flow requirements, plant specific work, fuel utilisation efficiency, power-to-heat-ratio, which are function of compressor pressure ratio and turbine inlet temperature, and process steam drum pressure. The maximum and minimum values of power-to-heat ratio are found with steam internal convection cooling and air internal convection cooling respectively whereas maximum and minimum values of fuel utilisation efficiency are found with steam internal convection cooling and closed loop steam cooling. The analysis is useful for power plant designers to select the optimum compressor pressure ratio, turbine inlet temperature, fuel utilisation efficiency, power-to-heat ratio, and appropriate cooling means for a specified value of plant specific work and process heating requirement.     

Exergy analysis of a thermal power plant with measured boiler and turbine losses

In this paper, a thermodynamic analysis of a subcritical boiler–turbine generator is performed for a 32 MW coal-fired power plant. Both energy and exergy formulations are developed for the system. A parametric study is conducted for the plant under various operating conditions, including different operating pressures, temperatures and flow rates, in order to determine the parameters that maximize plant performance. The exergy loss distribution indicates that boiler and turbine irreversibilities yield the highest exergy losses in the power plant. In addition, an environmental impact and sustainability analysis are performed and presented, with respect to exergy losses within the system.