共查询到18条相似文献,搜索用时 218 毫秒
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在建立输油管道基本方程组的基础上,对其进行场协同分析。结果表明:压力场 是输送过程的主导势场,温度场通过改变粘度等物性参数来影响压力场的分布,因而是过程的 辅助势场。 相似文献
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Yong传递的研究现状与发展方向 总被引:3,自引:1,他引:3
回顾了历史上Yong传递研究的形成与发展过程,并重点介绍了国内外Yong研究的现状,对现阶段Yong传递研究的方法概要地进行了分类,建议今后工程Yong传递的具体研究方向可以从典型Yong传递过程,复杂工程Yong传递问题,Yong传递过程强化/减弱方法,用能设备的Yong传递优化设计等方面开展。 相似文献
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利用Yong分析的方法对立窑系统进行了Yong分析,得出了Yong效率,Yong变质系数,找出了立窑系统能量利用的薄弱环节,提出了节能挖潜措施。 相似文献
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孙家宁 《能源技术(上海)》2003,24(3):93-96,99
Yong经济学是以Yong为核算对象的成本核算方法,以最小产品成本为目标函数,结合一定的Yong经济学评价指标,对能量系统进行分析、评价,得到改进的途径。文章基于Yong成本方程,对Yong费用方程进行了讨论,明确了过程Yong损的计价方法,提出了有效的Yong经济学系数。用能级概念可以更为全面的描述能流的品质,能级匹配是减小系统Yong损失的有效途径。文章将能级的概念引入热经济学计价体系,提出了基于能级分析的计价策略和评价指标。以联产模型为实例,进行了讨论。 相似文献
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从Yong的基本概念出发,阐述了物理Yong和化学Yong的计算方法,推导了热力学中常见热力过程的Yong变量表达式,为工程Yong分析提供了理论计算基础。 相似文献
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The exergy topological method is used to present a quantitative estimation of the exergy destroyed in an organic Rankine cycle (ORC) operating on R113. A detailed roadmap of exergy flow is presented using an exergy wheel, and this visual representation clearly depicts the exergy accounting associated with each thermodynamic process. The analysis indicates that the evaporator accounts for maximum exergy destroyed in the ORC and the process responsible for this is the heat transfer across a finite temperature difference. In addition, the results confirm the thermodynamic superiority of the regenerative ORC over the basic ORC since regenerative heating helps offset a significant amount of exergy destroyed in the evaporator, thereby resulting in a thermodynamically more efficient process. Parameters such as thermodynamic influence coefficient and degree of thermodynamic perfection are identified as useful design metrics to assist exergy‐based design of devices. This paper also examines the impact of operating parameters such as evaporator pressure and inlet temperature of the hot gases entering the evaporator on ORC performance. It is shown that exergy destruction decreases with increasing evaporator pressure and decreasing turbine inlet temperatures. Finally, the analysis reveals the potential of the exergy topological methodology as a robust technique to identify the magnitude of irreversibilities associated with real thermodynamic processes in practical thermal systems. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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以低品位热能驱动的有机朗肯循环发电系统,是实现将低品位热能转变为电能,进而提高热力系统总体热效率,降低污染排放的有效途径之一。本文建立了低品位热能发电系统火用分析模型,对以R245fa为工质的温度低于383.15 K的低品位热能有机朗肯循环余热发电系统进行了火用分析,得到了各环节的能量转换效率并确定了对系统性能影响最大的环节;通过改变蒸发器和冷凝器的压降和传热系数值,分析了主要换热设备的设计和运行性能参数对系统火用效率、热效率和发电量的影响趋势,提出了低品位热能发电系统的优化方向。 相似文献
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回顾了历史上传递研究的形成与发展过程 ,并重点介绍了国内外传递研究的现状 ,对现阶段传递研究的方法概要地进行了分类。建议今后工程传递的具体研究方向可以从典型传递过程、复杂工程传递问题、传递过程强化 /减弱方法、用能设备的传递优化设计等方面开展 相似文献
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在热平衡分析基础上建立了柴油机能质分析的平衡计算模型,并以WD615(162kW)型车用柴油机为对象进行了试验研究,对比分析柴油机工作过程中的能质分布规律和节能潜力。结果表明:在冷却水及排气能量利用之前,柴油机的热平衡规律和有效能利用率一致。在柴油机最大扭矩点(约1 600r/min),系统有效功占总热量的百分比达到最大值,效率、冷却水和排气的可用能比例也达到最大,约有17%的可用能还未得到利用。不可逆燃烧、有限温差传热和摩擦损耗等因素降低了系统能量的能级,减少柴油机系统的损同时梯级利用排气及冷却水能量,是车用柴油机节能的可行手段。分析方法也为柴油机的效率评价提供了一种新的参考方案。 相似文献
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采用锅炉效率的分析方法对某电站300MW锅炉在O2/CO2气氛下的各项损失和锅炉效率进行了计算,并与相同条件的空气气氛下的各项损失和锅炉效率进行了比较。结果表明,采用O2/CO2的富氧燃烧技术可大大提高锅炉热效率,并相应提高锅炉的效率,而燃烧过程和传热过程的损失仍是锅炉的主要损失。 相似文献
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The thermodynamic performance of an industrial waste heat recovery‐based trigeneration system is studied through energy and exergy efficiency parameters. The effects of exhaust gas inlet temperature, process heat pressure, and ambient temperature on both energy and exergy efficiencies, and electrical to thermal energy ratio of the system are investigated. The energy efficiency increases while electrical to thermal energy ratio and exergy efficiency decrease with increasing exhaust gas inlet temperature. On the other hand, with the increase in process heat pressure, energy efficiency decreases but exergy efficiency and electrical to thermal energy ratio increase. The effect of ambient temperature is also observed due to the fact that with an increase in ambient temperature, energy and exergy efficiencies, and electrical to thermal energy ratio decrease slightly. These results clearly show that performance evaluation of trigeneration system based on energy analysis is not adequate and hence more meaningful evaluation must include exergy analysis. The present analysis contributes to further information on the role of exhaust gas inlet temperature, process heat pressure, ambient temperature influence on the performance of waste heat recovery‐based trigeneration from a thermodynamic point of view. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献