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。     

闭式内可逆回热布雷顿热电冷联产装置(火用)分析

应用有限时间热力学理论和方法建立了闭式内可逆回热布雷顿热电冷联产装置模型,导出了装置无量纲(火用)输出率和效率的解析式。通过数值计算分析了回热器热导率对(火用)输出率和(火用)效率的影响,发现存在临界压比,同时优化了压比,研究了热电比、制冷和供热温度等设计参数对最优(火用)输出率和(火用)效率以及相应最佳压比的影响,发现最优(火用)输出率时的设计压比要大于最优(火用)效率时的设计压比,最优(火用)输出率和(火用)效率均随冷用户温度的升高而减小,分别存在最佳的热用户温度使(火用)输出率和(火用)效率取得最大值,热用户温度对装置最优(火用)性能的影响比冷用户温度更为明显。     

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。     

恒温热源内可逆Brayton热电联产循环的利润率密度分析

根据能量系统有限时间综合经济分析的思路,引入新的循环性能指标:利润率密度(定义为利润率与循环最大比容之比),对恒温热源内可逆Brayton热电联产循环的利润率密度特性进行了分析,并将最大利润率密度及最大利润率时的循环参数进行了对比.研究表明,与最大利润率工况相比,尽管最大利润率密度工况下循环的利润率有所减小,但循环的火用效率有较大幅度的提高,设备体积也大为减小,实现了循环利润率与设备体积的最佳折衷.本文的研究表明,利润率密度可以作为热电联产系统设计的一种备选方案.     

不可逆回热布雷顿CCHP装置FTT建模

应用有限时间热力学理论和方法(FTT)建立了闭式不可逆回热布雷顿热电冷联产(CCHP)装置模型,导出了装置无量纲可用能率、火用输出率、利润率、第一定律效率和火用效率的解析式。通过数值计算得到了各个性能指标与压比的关系,优化了压比。分析了设计参数对最优性能的影响,发现回热能够显著增大第一定律效率和火用效率;增大压气机和透平效率、压力恢复系数能够增大5个性能指标,但前者使相应压比增大,后者使相应压比减小;增大热电比能够显著增大可用能率和第一定律效率;分别存在最佳的供热温度使5个最优性能指标取得最大值;提高冷库温度能增大可用能率和第一定律效率,但会降低火用输出率、火用效率和利润率。     

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。     

恒温热源不可逆中冷回热布雷顿热电联产装置的火用经济性能优化

用有限时间热力学理论和方法研究了恒温热源不可逆中冷回热布雷顿热电联产装置的火用经济性能,导出了无量纲利润率和火用效率的解析式.以利润率和火用效率为目标,通过数值计算对热导率的分配、中间压比的选取进行了优化.得到了最大利润率和火用效率.进一步对总压比进行优化,得到了双重最大利润率,但火用效率不存在双重最大值.详细分析了设...     

中冷回热布雷顿热电联产装置的(火用)经济性能——不可逆恒温热源循环性能分析

用有限时间热力学理论和方法研究了恒温热源不可逆中冷回热布雷顿热电联产装置的经济性能,导出了无量纲利润率和效率的解析式.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,通过数值计算详细分析了各设计参数对循环一般性能和最优性能的影响,发现回热和中冷能够较大地提高装置的利润率和效率,并且随压比的变化对利润率和效率具有不同的影响.讨论了利润率和效率之间的关系,其特性关系为扭叶型.最后发现分别存在最佳用户侧温度使得利润率和效率取得双重最大值.     

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.     

广义不可逆联合制冷循环有限时间(火用)经济性分析与优化

研究了存在热阻、热漏和内不可逆性的广义不可逆联合制冷循环有限时间(火用)经济性能,导出在线性传热定律下循环最佳利润率和最佳制冷系数的解析式以及二者的优化关系,并用数值算例对比分析了热漏、内不可逆性和价格比对利润率和(火用)经济性能界限的影响.     

Ecological performance analysis of an endoreversible modified Brayton cycle

An endoreversible closed modified simple Brayton cycle model with isothermal heat addition coupled to variable-temperature heat reservoirs is established using finite-time thermodynamics. Analytical expressions of dimensionless power output, thermal efficiency, dimensionless entropy generation rate and dimensionless ecological function are derived. Influences of cycle thermodynamic parameters on ecological performance and optimal compressor pressure ratio, optimal power output, optimal cycle thermal efficiency and optimal entropy generation rate corresponding to maximum ecological function are obtained and compared with those corresponding to maximum power output. The results show that cycle thermal efficiency improvement and entropy generation rate reduction are obtained at the expense of higher compressor pressure ratio and a little sacrifice of power output at maximum ecological function. The compromises between power output and entropy generation rate and between power output and cycle thermal efficiency, respectively, are achieved.     

Thermodynamic analysis of an integrated power generation system driven by solid oxide fuel cell

A new integrated power generation system driven by the solid oxide fuel cell (SOFC) is proposed to improve the conversion efficiency of conventional energy by using a Kalina cycle to recover the waste heat of exhaust from the SOFC-GT. The system using methane as main fuel consists an internal reforming SOFC, an after-burner, a gas turbine, preheaters, compressors and a Kalina cycle. The proposed system is simulated based on the developed mathematical models, and the overall system performance has been evaluated by the first and second law of thermodynamics. Exergy analysis is conducted to indicate the thermodynamic losses in each components. A parametric analysis is also carried out to examine the effects of some key thermodynamic parameters on the system performance. Results indicate that as compressor pressure ratio increases, SOFC electrical efficiency increases and there is an optimal compressor pressure ratio to reach the maximum overall electrical efficiency and exergy efficiency. It is also found that SOFC electrical efficiency, overall electrical efficiency and exergy efficiency can be improved by increasing air flow rate. Also, the largest exergy destruction occurs in the SOFC followed by the after-burner, the waste heat boiler, the gas turbine. The compressor pressure ratio and air flow rate have significant effects on the exergy destruction in some main components of system.     

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.     

Energetic and exergetic performance analyses of a combined heat and power plant with absorption inlet cooling and evaporative aftercooling

In this paper, exergy method is applied to analyze the gas turbine cycle cogeneration with inlet air cooling and evaporative aftercooling of the compressor discharge. The exergy destruction rate in each component of cogeneration is evaluated in detail. The effects of some main parameters on the exergy destruction and exergy efficiency of the cycle are investigated. The most significant exergy destruction rates in the cycle are in combustion chamber, heat recovery steam generator and regenerative heat exchanger. The overall pressure ratio and turbine inlet temperature have significant effect on exergy destruction in most of the components of cogeneration. The results obtained from the analysis show that inlet air cooling along with evaporative aftercooling has an obvious increase in the energy and exergy efficiency compared to the basic gas turbine cycle cogeneration. It is further shown that the first-law efficiency, power to heat ratio and exergy efficiency of the cogeneration cycle significantly vary with the change in overall pressure ratio and turbine inlet temperature but the change in process heat pressure shows small variation in these parameters.     

Gas turbine steam injection and combined power cycles using fog inlet cooling and biomass fuel: A thermodynamic assessment

The results of energy and exergy analyses of two biomass integrated steam injection cycles and combined power cycles are reported. Fog cooling, steam injection and adding steam turbine cycles to gas turbine cycles can enhance the performance of power generation systems. Even with its lower heat value, biomass can be substituted for fossil fuels. The performances of the cycles are assessed under the same conditions. The assessments show that the combined cycle has a higher efficiency at lower values of compressor pressure ratio but the steam injection plant is advantageous at higher pressure ratio values. The steam injection plant has a higher net power under the same conditions, while the exergy loss rate is higher for the combined cycle at all pressure ratios. But the exergy destruction rate is higher for the steam injection cycle at lower compressor pressure ratios, and for the combined cycle at higher pressure ratios.     

变温热源内可逆中冷回热布雷顿循环功率密度优化

以功率密度为目标,用有限时间热力学的方法,通过数值计算,对变温热源条件下的内可逆中冷回热布雷顿循环的高、低温侧换热器的热导率分配和中间压比、循环总压比和工质与热源间的热容率匹配进行优化。分别得到了最大功率密度、双重最大功率密度和三重最大功率密度,并分析了热力学参数对高低温侧换热器的热导率最优分配、最佳中间压比、最大功率密度和双重最大功率密度的影响。     

开式燃气轮机中冷回热再热循环功率和效率优化

建立了开式燃气轮机中冷回热再热（ICRR）循环有限时间热力学模型,导出了循环功率和效率解析式,优化了气流沿通流部分的压降（或低压压气机进口空气质量流率）和中间压比,得到最大功率;并在给定燃油流率的情况下,优化了气流沿通流部分的压降和中间压比,得到最大热效率,进一步在给定低压压气机进口和动力涡轮出口总面积的情况下,优化两者面积分配比,得到双重最大热效率.     

普适内可逆热机循环模型的(火用)经济性能优化

用有限时间热力学方法分析工作在恒温热源TH、TL之间内可逆普适热机循环模型的经济性能,导出循环利润率与工质温比、热效率与工质温比的关系式;以及利润率和效率的特性关系。所得结果包含了内可逆D iese、lO tto、A tk inson和B rayton循环的有限时间经济性能。