共查询到19条相似文献,搜索用时 421 毫秒
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为改善氨工业制冷系统的运行能效和经济性,对螺杆式制冷机组系统,提出一种回收压缩机氨蒸气显热部分冷凝热和油冷却器润滑油余热的组合式热回收方案。该方案在压缩机排气管上增设氨热回收器,在油分离器和油冷却器之间增设油热回收器。理论计算表明,热回收系统所回收的总热负荷相较于压缩机输入功率的百分比R_(t,p)可达84. 2%~99. 6%,而组合式热回收系统的综合性能系数COP_c比无热回收制冷系统的COP高29. 0%~62. 5%。系统改造实例表明,本组合式热回收方案节能效益显著,系统改造投资的静态回收期较短。 相似文献
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热法磷酸燃烧塔内传热特性的工程计算方法 总被引:12,自引:0,他引:12
在对热法磷酸燃烧塔进行余热利用的技术改造过程中,迫切需要了解燃烧塔内的传热特性,并准确地计算出塔内的换热量.本文分析了热法磷酸燃烧塔内的传热特性及其影响因素,提出了热法磷酸燃烧塔内传热特性的工程计算方法,由此可以获得余热回收换热量的计算公式.本文对某燃烧塔进行了实际计算,所获得的磷酸余热回收换热量与实验值的比较,误差在10%以内,满足工程计算的精度要求。这不仅为热法磷酸的余热利用提供了理论指导,而且在实际的磷燃烧塔余热利用的技术改造过程中也具有很强的工程应用价值. 相似文献
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《工程热物理学报》2017,(7)
熵产、炳损最小等准则函数法及传统能量流法是热系统性能优化的常用方法,但这些方法难以整体揭示热系统中的部件特性和拓扑特征,增加了系统整体分析和优化的难度。本文基于(火积)理论,利用流体进口温差(或算数平均温差)为特征温差重新定义了换热器的热阻,揭示了热量输运中驱动力和阻抗的本构关系,提出了换热器稳态性能分析的能量流法。在此基础上,针对双回路热管理系统,根据其拓扑特征及换热器的热阻构建了系统的能量流模型;基于基尔霍夫定律,揭示了系统中包含传递和输运两种阻力的热量整体输运规律。最后,应用拉格朗日乘子法优化该系统,获得了系统中换热器的最小总热导及热容量流的最佳分配,说明了本文基于(火积)理论提出的新能量流法在热系统分析和优化中的先进性。 相似文献
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冷热电联产系统的评价准则 总被引:14,自引:3,他引:11
本文通过对以燃气轮机回热循环为动力系统的冷热电联产系统进行热力学分析,对几种常用的评价准则进行了比较。通过分析,认为能量利用系数将冷、热、电等各股能量等价看待,(火用)效率过分看重能量的作功能力,折合发电效率过分关注冷、热能的输出,均不适于冷热电联产系统的评价;节能率反映的是输入能量的使用情况,经济(火用)效率在某种程度上是经济性的表现,比较适于冷热电联产系统的评价。研究中发现,燃气轮机温比有利于系统性能的提高,但针对不同的目标有不同的最佳压比;在节能率的使用中需要明确参照系统的性能。 相似文献
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节能控制能够有效降低能耗,对保护环境等方面具有重要影响。但目前大多数电子节能控制器都是通过采用单片机技术和双向晶闸管过零触发交流调压电路对电子节能控制器进行设计。通过介绍电子的负荷特点和节能原理,分析电子节能控制器的硬件组成电路,并对电子节能控制器的主要软件程序的流程图进行设计,完成电子节能控制器设计。但这种方法节能控制效果较低,难以保证电子节能控制器性能,为此,提出一种基于模糊PID控制的嵌入式电子节能控制器设计与实现方法。首先通过对嵌入式电子节能控制器的处理器、电源电路、复位电路、系统时钟电路、JTAG接口电路、D/A转换电路、功放电路、双极性电源电路以及嵌入式电子节能控制器硬件PCB板器件布局等的设计,完成嵌入式电子节能控制器硬件设计。在此基础上,选用模糊PID控制方法对嵌入式电子节能控制器进行设计。通过分析模糊PID控制原理,介绍加入自调节因子的模糊PID控制的算法设计,以此确定输入输出隶属度函数,再利用模糊推理和模糊规则,得到电子节能控制器的模糊控制过程,从而完成嵌入式电子节能控制器的设计。实验证明,所提方法能够有效提高嵌入式电子节能控制器的节能控制效果,具有良好的使用价值。 相似文献
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为了研究曲率能对核裂变热力学驱动力(TDF)的影响,首先利用包含曲率能的截断版小液滴模型计算了200Pb和224Th的位垒和熵垒,对比液滴模型的计算结果表明:曲率能未改变224Th的位垒鞍点,却将200Pb的位垒鞍点向后推移。能级密度参数的形变关系越强则两系统的熵垒鞍点越靠近基态。为了进一步探究曲率能如何通过位势和熵势影响TDF,以断前中子多重性(PNM)为探针,通过两种方案进行了模拟,结果表明:曲率能降低了两系统的位势驱动力,而增强了其熵势驱动力。结合PNM的计算表明,前一种效应要比后一种效应明显,因此曲率能总体减弱了200Pb和224Th的TDF,进而延缓了两系统的核裂变进程。In order to study the effect of curvature energy on the thermodynamic driving force (TDF) of nuclear fission, the potential and entropy barrier of 200Pb and 224Th systems are calculated by using the truncated droplet model including curvature energy, respectively. Compared with the liquid drop model, the results show that curvature energy does not affect the saddle point of 224Th, but pushes the saddle point of 200Pb backwards the ground state. The stronger the deformation dependence of the level density parameter is, the closer the saddle point of entropy barrier for these systems is to the ground state. In order to further investigate how curvature energy affects TDF through nuclear potential and entropy, respectively, the prescission neutron multiplicity (PNM) is selected as the probe, some simulations based on two schemes are carried out. The results show that curvature energy reduces the potential driving force of 200Pb and 224Th, and enhances the entropy potential driving force. Combined with the calculations and analyses of PNM, the former effect is more obvious than the latter, so curvature energy weakens TDF of two systems on whole, thus delaying the nuclear fission process of two systems. 相似文献
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利用动力学加统计模型对200Pb 系统的断前中子的发射进行了模拟。计算结果表明,在核耗散的形变关系(DDND) 确定的情况下,断前中子多重性会随着能级密度坐标关系(DDLDP) 的增强而减少,且该规律主要由第一阶段内断前中子的发射决定。此外,选定DDLDP 而采用核耗散的不同形变关系也都很好地重现了实验数据。为了解释上述现象,提出了研究热核退激的路径分析方法,其主要内容是把核耗散看成是实验粒子在拉伸维度上的阻尼力,而核裂变的动力学过程是该阻尼力和自由能产生的驱动力之间相互竞争的结果。利用该方法对200Pb 系统的断前中子多重性进行了分析,并指出在确定DDND时应考虑DDLDP。Within a certain deformation dependence of nuclear dissipation (DDND), the simulation results about the deexcitation process of 200Pb show that the prescission neutron multiplicities decrease with increasing deformation dependence of level density parameter (DDLDP). Moreover, this pattern is determined by the emission of prescission neutron in the first period of nuclear fission. On the other hand, all of the results from two kinds of different DDNDs can reproduce the experiment data perfectly with a certain DDLDP. In order to illustrate those phenomena, the pathwise analysis method (PAM) is presented in this paper. In the PAM, nuclear dissipation is treated as the damping force on the elongation dimension, whereas the fission dynamics process results from the competition between damping force and the driving force stemming from the nuclear free energy. The prescission neutron multiplicity in the deexcitation process of 200Pb is analyzed, and the results point out that the DDLDP needs to be taken into account in studying the DDND. 相似文献
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Lina Si Dan Guo Jianbin Luo Guoxin Xie 《Applied Physics A: Materials Science & Processing》2012,109(1):119-126
In the chemical mechanical polishing (CMP) process, the complex behaviors of abrasive particles play important roles in the planarization of wafer surface. Particles embedded in the pad remove materials by ploughing, while particles immersed in the slurry by rolling across the wafer surface. In this paper, processes of the particle rolling across a silicon surface with an asperity under various down forces and external driving forces were studied using molecular dynamics (MD) simulation method. The simulations clarified the asperity shape evolution during the rolling process and analyzed the energy changes of the simulation system and the interaction forces acted on the silica particle. It was shown that both the down force and the driving force had important influences on the amount of the material removed. With relatively small down forces and driving forces applied on the particle, the material removal occurred mainly in the front end of the asperity; when the down forces and driving forces were large enough, e.g., 100?nN, the material removal could take place at the whole top part of the asperity. The analysis of energy changes and interaction forces provided favorable explanations to the simulation results. 相似文献
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熵产是非平衡热力学中的核心物理量,传统上表示为广义力(驱动力)与广义流的乘积.这种表达存在两方面缺陷:一是广义力与广义流的拆分具有任意性;更重要的是,以其计算热波传递时熵产可以为负值,从而违反热力学第二定律.本文基于热质理论分析表明,传热过程的熵产实质上是由热质流体的热质能耗散引起的,所以熵产中的力不是驱动力而是阻力,并且具有力的量纲.由此提出的熵产修正表达式,不仅在计算热波传递过程中熵产恒为正值,与扩展不可逆热力学中的熵产表达式一致,而且不存在力和流拆分的任意性. 相似文献
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Andy T. Wu John Mammosser Jean Delayen Amy Wilkerson Robert Ike 《Applied Surface Science》2007,253(6):3041-3052
It was demonstrated that smooth Nb surfaces could be obtained through buffered electropolishing (BEP) employing an electrolyte consisting of lactic, sulfuric, and hydrofluoric acids. Parameters that control the polishing process were optimized to achieve a smooth surface finish. The polishing rate of BEP was determined to be 0.646 μm/min which was much higher than 0.381 μm/min achieved by the conventional electropolishing (EP) process widely used in the superconducting radio frequency (SRF) community. Root mean square measurements using a 3D profilometer revealed that Nb surfaces treated by BEP were an order of magnitude smoother than those treated by the optimized EP process. The chemical composition of the Nb surfaces after BEP was analyzed by static and dynamic secondary ion mass spectrometry (SIMS) systems. SIMS results implied that the surface oxide structure of Nb might be more complicated than what usually believed and could be inhomogeneous. Preliminary results of BEP on Nb SRF single cell cavities and half-cells were reported. It was shown that smooth and bright surfaces could be obtained in 1800 s when the electric field inside a SRF cavity was uniform during a BEP process. This study showed that BEP is a promising technique for surface treatment on Nb SRF cavities to be used in particle accelerators. 相似文献
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The aim of this paper is to present a discrete event model-based approach to simulate train movement with the considered energy-saving factor. We conduct extensive case studies to show the dynamic characteristics of the traffic flow and demonstrate the effectiveness of the proposed approach. The simulation results indicate that the proposed discrete event model-based simulation approach is suitable for characterizing the movements of a group of trains on a single railway line with less iterations and CPU time. Additionally, some other qualitative and quantitative characteristics are investigated. In particular, because of the cumulative influence from the previous trains, the following trains should be accelerated or braked frequently to control the headway distance, leading to more energy consumption. 相似文献
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为了解决油田抽油机采油效率和能耗较低等问题,本课题在抽油机单井变频节能控制技术的基础上,研发了丛式抽油机井群单井多模式柔性控制器,并建立丛式机井群一拖四的集中控制方案。通过选择合理的优化算法,实现了单井柔性控制与井组集中优化控制的有机结合,有针对性的提高了井群的整体能效。现场测试效果表明:该丛式抽油机柔性集中控制系统能够适应现场工况条件,实现抽油机井群系统的优化控制,并且能达到较好的控制效果与节能效果。 相似文献