共查询到18条相似文献,搜索用时 562 毫秒
1.
采用有限时间热力学的思想,建立了高炉余能余热驱动的变温热源不可逆中冷回热(ICR)布雷顿热电联产(CHP)装置模型.以(火用)输出率和炯效率为目标优化了装置的性能,发现回热器对炯性能的影响在所有换热器中是最小的,当给定回热器热导率分配时,分别存在两个最佳的中间压比和两组最佳的高、低温侧和热用户侧换热器以及中冷器的热导率分配使炯输出率和炯效率取得最大值.进一步优化总压比,得到了双重最大(火用)输出率和炯效率.增大高炉余热源入口温度、压力恢复系数、压气机和涡轮机效率有利于提高装置的炯性能,在一定范围内,热用户温度越高越好.最后发现分别存在最佳的工质与热源间的热容率匹配使(火用)输出率和(火用)效率取得三重最大值. 相似文献
2.
运用热力学火用分析的方法,分别考虑了高低温侧换热器、热回收装置侧换热器和中冷器的热阻损失,以及压缩机和涡轮机中的内不可逆损失,以无因次总输出火用和火用效率为目标函数,借助数值分析的方法,研究了恒温热源条件下不可逆中冷焦耳—布雷顿功热并供系统的火用性能,分析了主要特征参数对无因次总输出火用及火用效率的影响。分析结果表明,当中间压比不变而总压比变化时,存在一组最佳运行参数,使无因次总输出火用达到最大,还存在最大的总输出火用和火用效率以及相对应的一组最佳运行参数。提高中冷器换热有效度可以增加无因次总输出火用和火用效率。 相似文献
3.
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 总被引:1,自引:1,他引:0
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. 相似文献
4.
5.
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。 相似文献
6.
7.
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。 相似文献
8.
9.
10.
11.
In the present work, exergy analysis of a coal‐based thermal power plant is done using the design data from a 210 MW thermal power plant under operation in India. The entire plant cycle is split up into three zones for the analysis: (1) only the turbo‐generator with its inlets and outlets, (2) turbo‐generator, condenser, feed pumps and the regenerative heaters, (3) the entire cycle with boiler, turbo‐generator, condenser, feed pumps, regenerative heaters and the plant auxiliaries. It helps to find out the contributions of different parts of the plant towards exergy destruction. The exergy efficiency is calculated using the operating data from the plant at different conditions, viz. at different loads, different condenser pressures, with and without regenerative heaters and with different settings of the turbine governing. The load variation is studied with the data at 100, 75, 60 and 40% of full load. Effects of two different condenser pressures, i.e. 76 and 89 mmHg (abs.), are studied. Effect of regeneration on exergy efficiency is studied by successively removing the high pressure regenerative heaters out of operation. The turbine governing system has been kept at constant pressure and sliding pressure modes to study their effects. It is observed that the major source of irreversibility in the power cycle is the boiler, which contributes to an exergy destruction of the order of 60%. Part load operation increases the irreversibilities in the cycle and the effect is more pronounced with the reduction of the load. Increase in the condenser back pressure decreases the exergy efficiency. Successive withdrawal of the high pressure heaters show a gradual increment in the exergy efficiency for the control volume excluding the boiler, while a decrease in exergy efficiency when the whole plant including the boiler is considered. Keeping the main steam pressure before the turbine control valves in sliding mode improves the exergy efficiencies in case of part load operation. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
12.
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. 相似文献
13.
14.
Combined cycle power plants (CCPPs) are in operation with diverse thermodynamic cycle configurations. Assortment of thermodynamic cycle for scrupulous locality is dependent on the type of fuel available and different utilities obtained from the plant. In the present paper, seven of the practically applicable configurations of CCPP are taken into consideration. Exergetic and energetic analysis of each component of the seven configurations is conducted with the help of computer programming tool, i.e., engineering equation solver (EES) at different pressure ratios. For Case 7, the effects of pressure ratio, turbine inlet temperature and ambient relative humidity on the first and second law is studied. The thermodynamics analysis indicates that the exergy destruction in various components of the combined cycle is significantly affected by the overall pressure ratio, turbine inlet temperature and pressure loss in air filter and less affected by the ambient relative humidity. 相似文献
15.
The main objective of this study, which is conducted for the first time to the best of the authors' knowledge, is to identify improvements in olive oil refinery plants' performance. In the analyses, the actual operational data are used for performance assessment purposes. The refinery plant investigated is located in Izmir Turkey and has an oil capacity of 6250 kg h−1. It basically incorporates steam generators, several tanks, heat exchangers, a distillation column, flash tanks and several pumps. The values for exergy efficiency and exergy destruction of operating components are determined based on a reference (dead state) temperature of 25°C. An Engineering Equation Solver (EES) software program is utilized to do the analyses of the plant. The exergy transports between the components and the consumptions in each of the components of the whole plant are determined for the average parameters obtained from the actual data. The exergy loss and flow diagram (the so‐called Grassmann diagram) are also presented for the entire plant studied to give quantitative information regarding the proportion of the exergy input that is dissipated in the various plant components. Among the observed components in the plant, the most efficient equipment is found to be the shell‐ and tube‐type heat exchanger with an exergy efficiency value of 85%. The overall exergetic efficiency performance of the plant (the so‐called functional exergy efficiency) is obtained to be about 12%, while the exergy efficiency value on the exergetic fuel–product basis is calculated to be about 65%. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
16.
17.
In search for clean energy solutions in a global warming era, oxy‐fuel combustion systems are promising. In the study, combustion products are calculated, and exergy analysis is done using the proposed multifeature equilibrium combustion model. And the results obtained for oxy‐combustion of different fuels at various oxygen fractions are given in comparison with conventional combustion. For validation, the model results are compared with popular combustion calculation tools, GASEQ and CEA. Effect of oxygen content on oxy‐combustion exergy analysis is calculated, also considering changes in equivalence ratio and combustion chamber inlet temperature. Moreover, indicating parameters for combustion performance, temperature ratio, chemical exergy, physical exergy, total specific exergy, and exergy destruction are utilized in the calculations elaborately. Changes in combustion product mole fractions are explained for rich and lean combustion regions. And also, specific exergy results are presented. In terms of exergy destruction, oxy‐combustion is more advantageous than conventional combustion. It has been shown that exergy destruction in combustion process with conventional air is approximately 1.5 times higher compared with 21% oxy‐combustion, both at different equivalence ratios and at different combustion chamber inlet temperatures. Nowadays, environment‐friendly, clean energy production systems are growing in numbers. In this concept, exergetic analyses of combustion for different fuels and greener natural gas, compared with diesel, gasoline, and methanol, are given in comparison. Considering four fuel types, advantageous and disadvantageous cases are presented for oxy‐combustion at different oxygen fractions and conventional combustion. As a result, diesel fuel is more advantageous than the other three fuel types, in terms of temperature ratio and exergy. Natural gas combustion appears to be disadvantageous in terms of specific exergy and temperature ratio, but it is the most advantageous in terms of exergy destruction. Consequently, distinctive comparison is done for oxy‐combustion and conventional combustion, determining positive and negative effects for different fuels. 相似文献