共查询到20条相似文献,搜索用时 343 毫秒
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《能源工程》2019,(6)
采用Aspen Plus中的序贯模块法撕裂物流,模拟二级自动复叠系统。理论分析采用Visual Basic for Application(VBA)编写遗传算法,通过ActiveX技术将VBA与Aspen Plus进行对接,通过改进的自适应度遗传算法对循环进行寻优,将循环的热力学完善度作为目标函数,并引入惩罚函数得到适应度函数;优化了不同蒸发温度、冷凝温度、压缩机压比下循环在热力学完善度最高时的制冷工质配比,为实际自动复叠制冷系统设计和制冷剂充注提供理论数据。仿真生成了蒸发冷凝器温度与换热量曲线,发现最优时第一级蒸发冷凝器传热窄点在热流体出口处,而第二级蒸发冷凝器传热窄点在换热器中部和热流体出口处。 相似文献
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为解决传统耦合太阳能辅热的先进绝热压缩空气储能(AA-CAES+CSP)系统热能损失大的问题,提出其释能过程的改进方案。从热力学和经济学角度对改进前后的系统性能进行比较分析。结果表明,改进系统的热、冷能性能系数及年利润率显著提高。同时,进行参数敏感性分析,结果表明:集热温度升高,改进系统的冷能性能系数下降,两系统其他指标上升;储气室压差越大,系统年利润率越高,而其他指标越低;压缩/膨胀功率增大,年利润率减小,而其他指标增大。此外,以循环效率和年利润率为目标函数,采用灰狼算法对系统进行多目标优化,设置较高集热温度、压缩/膨胀功率和较低储气室压比时,更易获得最佳系统性能。 相似文献
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DUSáAN P. SEKULICá 《传热工程》2013,34(1-2):83-88
The entropy generation (irreversibility) concept founded on the second law of thermodynamics may be applied in heat exchanger analysis. In this paper the quantity termed enthalpy exchange irreversibility norm (EEIN) is the measure of the internal heat exchanger irreversibilities. The behavior of EEIN as a function of the heat exchanger thermal size is discussed for an arbitrary flow arrangement and more precisely for two characteristic limiting cases: cocurrent and countercurrent heat exchangers. 相似文献
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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
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以非平衡热力学理论为基础,通过引入可用能这个汽液相变换热过程的一个重要的功势函数,对汽液相变系统的可用能进行了分析,得到了汽液相变系统的可用能变化的计算式,并以此为判据来分析汽液相变系统的稳定性,得到了汽液相变系统的相平衡条件、力学稳定性条件和热稳定性条件。并给出了有关物理意义;定义了汽液相变时的汽、液相的力稳边际曲线。结果表明,汽液相变系统的力稳条件不同于简单可压缩单相系统的力稳条件,相变力稳边际曲线是相变时不可逾越的界限。 相似文献
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Thermodynamically consistent description of heat conduction with finite speed of heat propagation 总被引:1,自引:0,他引:1
Isaac Shnaid 《International Journal of Heat and Mass Transfer》2003,46(20):3853-3863
In this work, governing equations for heat conduction with finite speed of heat propagation are derived directly from classical thermodynamics. For a one-dimensional flow of heat, the developed governing equation is linear and of parabolic type. In a three dimensional case, the system of nonlinear equations is formulated.Analytical solutions of the equations for one-dimensional flow of heat are obtained, and their analysis shows characteristic features of heat propagation with finite speed, being fully consistent with classical thermodynamics. 相似文献
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对竖直圆管内空气强迫对流换热与自然对流换热进行了实验,从量级上表明了两者的不同,由实验得到了用雷诺数表示的自然对流换热关联式,与现有的大空间自然对流换热公式作了比较。 相似文献
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《International Journal of Hydrogen Energy》2021,46(74):36982-36994
Compared to the low-temperature proton exchange membrane fuel cell (LT-PEMFC) system, the high-temperature proton exchange membrane fuel cell (HT-PEMFC) system has a simple balance of plant (BOP) configuration and high heat recovery efficiency. However, to commercialize this system, the start-up time should be shortened. This study aims to develop a preheating methodology for the 5 kW HT-PEMFC system, which is the target system. The entire start-up time of this system is dominated by the warm-up time of the stack among various other system components. An advanced preheating method was experimentally verified by combining three heating methods of the stack: coolant heating, reaction heating, and air heating. Additionally, considering the power consumption of the target system, a method to reduce the warm-up time was proposed. Ultimately, we found that the combined coolant and reaction heating method was the best. Furthermore, a case study revealed that using an oil heater with variable heating capacity on the target system can reduce the start-up time by 23% compared to a fixed capacity heater. 相似文献
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基于热力学第一定律,反映热泵能量数量关系的性能指标-供热系数,在用于评价热泵系统节能效益及对热泵系统进行可行性评价的问题上,存在一定的局限性。本文对这一问题进行了分析。在此基础上,根据热力学第二定律,提出了以热泵系统单位火用损供热率作为其性能评价指标的思想。以此作为热泵系统的性能评价指标,更科学、更客观。 相似文献