搅拌液体风力致热装置的热力学分析

依据热力学第一定律和热力学第二定律,对搅拌液体致热装置进行能量分析和火用分析,建立搅拌液体致热装置的能量平衡分析模型和火用平衡分析模型,并分析搅拌液体致热装置各环节的能源利用状况,从而给出提高搅拌液体致热装置的能量效率和火用效率的途径,对搅拌液体致热装置今后的节能设计具有重要的指导作用。     

加氢裂化装置的流程模拟及用能分析

科学地分析评价炼油过程用能状况是节能工作的基础.以某炼油厂加氢裂化装置为例,利用PRO/Ⅱ软件模拟加氢裂化装置,运用过程系统三环节能量结构理论,依据热力学第一定律和热力学第二定律进行了装置的能量平衡和(火用)平衡计算及分析,并根据分析结果指出了装置的节能方向.     

柴油机排气微粒捕捉器再生条件及分析

柴油机排气微粒捕捉器的关键技术是捕捉器的再生。文章提出了平衡微粒沉积量的概念，并根据Arrhenius方程，从平衡微粒沉积量的角度对微粒捕捉器的再生条件，再生的影响因素及再生的技术途径和方法进行了研究。利用能量平衡方程对微粒捕捉器强制热再生时的能量消耗以及可以采取的一些技术措施进行了分析。研究结果可以为柴油机排气微粒捕捉器再生技术的选择提供依据。     

二类热泵在利用余热供热中的热力分析

对单级二类吸收式热泵进行热力分析,建立了热泵系统各部分质量守恒、能量平衡和火用分析数学模型。根据火用平衡方程计算了各个部分的火用损失和热泵系统的火用效率。分析了溶液换热器稀溶液温差、热源温差、余热源温度和冷却水温度对火用损失、循环倍率和COP等的影响。对热泵系统进行了火用能质量评定,确定了火用能的薄弱环节。     

一种柴油机排气微粒喷油助燃再生装置设计与试验研究

设计了一种柴油机排气加热装置.该装置的创新点在于从柴油机涡轮增压器取出新鲜二次空气供给燃烧器燃烧,加热排气.以BJ493ZQ3增压发动机为试验用发动机,将该装置加装在柴油机排气管尾端,应用于微粒捕集器喷油助燃再生中,对该装置应用的可行性进行了论证,对其加热能力进行了试验研究.试验表明,该排气加热装置能在发动机较大工况范围内快速加热排气到500℃以上,有效燃烧微粒使捕集器可靠再生,同时易于车载,较好解决了微粒捕集器热再生存在的问题.     

浅析衡量用能水平的经济指标

本文借助四种物理模型,从能量平衡、(火用)平衡和能级平衡等三个侧面对加热过程进行了用能水平的分析和评价。在这些平衡方法基础上定义的能量经济指标,从不同角度反映了热力设备在能量转换能力方面的优劣程度,显示了它们在节约用能,合理用能等节能领域中的地位。     

天然气压力能回收装置热力学分析

高压天然气调压过程中存在着巨大的可供回收的压力能,节流阀、透平膨胀机、气波制冷机、涡流管是典型的能量回收设备。在对上述四种能量回收装置进行简要介绍之后,以[火用]概念为基础,以[火用]平衡为工具,对其进行了全面的热力学分析。结果表明：透平膨胀机的火用效率最高,其次是气波制冷机、涡流管、节流阀,且当膨胀比变化时,透平膨胀机的性能较稳定。涡流管、气波制冷机具有分离效果,可用于天然气脱水预冷。研究结果对于压力能回收装置的选用和调压流程的优化具有一定的指导意义。     

提高催化裂化装置三机组能量回收率的试验及应用

针对催化裂化装置能量回收机组能量回收率不高的现象,通过向再生器烟气管道中注入工业风,燃烧一段再生器烟气中的CO的方法,提高了烟气的温度和流量,进而提高了烟气轮机的效率和机组的能量回收率。工业试验证明,该方法切实可行,对催化裂化装置节能降耗有着实际价值,可使主电机功率降低600kW。     

空分系统能量的量与质分析

本文应用能量平衡法和(火用)平衡法对11—800型空分系统的能量分布进行了较为深入细致的综合分析。克服以往在能源工作中单一采用能量平衡法分析热力系统热力学完善度的片面性,将能量的数量与能量的品质结合起来讨论,特别明确了用能和节能的本质是指能量中可对系统作有用功的那部分可用能。     

盐浴炉快速启动的能质分析与全面节能

以能的质量((火用)平衡)分析盐浴炉的能量平衡。传统启动方法有效能利用较低,但盐浴炉的节能工作必须全面考虑。     

车用柴油机节能潜力的能质分析方法与试验研究

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。     

Energy and exergy analysis of a new hydrogen-fueled power plant based on calcium looping process

A novel hydrogen-fueled power plant with inherent CO₂ capture based on calcium looping process is proposed in this paper. The analyzed system has been evaluated from the energy and exergy points of view, it enables determination of the contribution of main component to the total exergy loss. The results show that energy and exergy efficiencies of the system are 42.7% and 42.25% respectively, combustion chamber and regenerator are responsible for large exergy destructions, mainly due to irreversibilities associated with the combustion reactions, they have great potential for system efficiencies improvements. The effects of various air pressure ratios and gas turbine inlet temperatures on the system thermodynamic performance are also presented. The thermodynamic efficiencies increase with the increase in air pressure ratios and gas turbine inlet temperatures.     

Simulated energy and exergy analyses of the charging of an oil-pebble bed thermal energy storage system for a solar cooker

Energy balance equations are used to model the solar energy capture (SEC) system and the thermal energy storage (TES) system of a proposed indirect solar cooker. An oil-pebble bed is used as the TES material. Energy and exergy analyses are carried out using two different charging methods to predict the performance of the TES system. The first method charges the TES system at a constant flowrate. In the second method, the flowrate is made variable to maintain a constant charging temperature. A Simulink block model is developed to solve the energy balance equations and to perform energy and exergy analyses. Simulation results using the two methods indicate a greater degree of thermal stratification and energy stored when using constant-temperature charging than when using constant-flowrate charging. There are greater initial energy and exergy rates for the constant-flowrate method when the solar radiation is low. Energy efficiencies using both methods are comparable whilst the constant-temperature method results in greater exergy efficiency at higher levels of the solar radiation. Parametric results showing the effect of each charging method on the energy and exergy efficiencies are also presented.     

微网风电系统的储能火用模型与火用经济研究

微网风电系统加装储能装置联合运行时,存在多种异质能量的相互转化,因此对系统性能的有效评估较为困难。为了准确衡量风能在系统中的利用、转化、损失特性,文章基于[火用]经济学基本原理,建立微网风储系统[火用]平衡及[火用]成本守恒模型,并依据所建模型确定系统各单元[火用]效率;同时确立[火用]优化潜力、成本差及[火用]经济因子的系统性能评估指标,并对微网热力学特性及经济性进行有效分析。通过试验表明,该模型能够可靠地对微网风储系统能效及经济性进行评估,可指明系统[火用]效率极大化的优化目标。     

Energy and exergy analyses of cold thermal storage systems

This study deals with the assessment of the thermodynamic performance of cold thermal storage systems using exergy and energy analyses. Several cases are considered, including some storages which are homogeneous, and others which undergo phase changes. In some cases the storages are stratified. A full cycle of charging, storing and discharging is considered for each case. Four cold thermal storage cases are presented in an illustrative example. The results demonstrate that exergy analysis provides more realistic and accurate assessments of the efficiency and performance of cold thermal storage systems than those given by the more conventional energy analysis. In addition, exergy analysis is conceptually more direct since it treats cold as a valuable commodity. It is concluded that the potential usefulness of exergy analysis in addressing and solving cold thermal storage problems is substantial. Copyright © 1999 John Wiley & Sons, Ltd.     

Comparison of energy,exergy, and entropy balance methods for analysing double‐stage absorption heat transformer cycles

The energy, exergy and entropy balance methods are used to analyse a double‐stage LiBr‐water absorption heat transformer cycle. An energy balance comparing component energy transfer is used to determine energy calculations. An exergy balance is employed to evaluate exergy destruction, and an entropy balance to verify entropy generation. A comparison of the results by the second law exergy and entropy balances indicates that they are consistent in identifying the location and relative significance of key non‐idealities within the system. The results obtained clearly show the influence of irreversibilities of individual components on deterioration of the effectiveness and the coefficient of performance of the system. The second law analysis offers an alternative view of cycle performance and provides an insight that the first law analysis cannot. The differences between the first law analysis by energy balance method and second law analysis by exergy and entropy balance methods are illustrated quantitatively for the double‐stage absorption heat transformer cycle, and the limitations and advantages of these methods are presented and discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Comparison of energy and exergy efficiencies of an underground solar thermal storage system

In this experimental study, solar energy was stored daily using the volcanic material with the sensible heat technique. The external heat collection unit consisted of 27 m² of south‐facing solar air collectors mounted at a 55° tilt angle. The dimensions of the packed‐bed heat storage unit were 6 × 2 × 0.6 m deep. The packed‐bed heat storage unit was built under the soil. The heat storage unit was filled with 6480 kg of volcanic material. Energy and exergy analyses were applied in order to evaluate the system efficiency. During the charging periods, the average daily rates of thermal energy and exergy stored in the heat storage unit were 1242 and 36.33 W, respectively. Since the rate of exergy depends on the temperature of the heat transfer fluid and surrounding, the rate of exergy increased as the difference between the inlet and outlet temperatures of the heat transfer fluid increased during the charging periods. It was found that the average daily net energy and exergy efficiencies in the charging periods were 39.7 and 2.03%, respectively. The average daily net energy efficiency of the heat storage system remained nearly constant during the charging periods. The maximum energy and exergy efficiencies of the heat storage system were 52.9 and 4.9%, respectively. Copyright © 2004 John Wiley & Sons, Ltd.     

Energy and exergy analyses of a raw mill in a cement production

Cement production has been one of the most energy intensive industries in the world. In order to produce raw materials preparation, clinker and rotary kilns are widely used in cement plants. The objective of this study is to perform energy and exergy analysis of a raw mill (RM) and raw materials preparation unit in a cement plant in Turkey using the actual operational data. The RM has a capacity of 82.9 ton-material hourly. Both energy and exergy efficiencies of the RM are investigated for the plant performance analysis and improvement, and are determined to be 84.3% and 25.2%, respectively. The present technique is proposed as a useful tool in the analysis of energy and exergy utilization, developing energy policies and providing energy conservation measures.     

Energy and exergy analysis of a latent heat storage system with phase change material for a solar collector

Analysis of energy and exergy has been performed for a latent heat storage system with phase change material (PCM) for a flat-plate solar collector. CaCl₂·6H₂O was used as PCM in thermal energy storage (TES) system. The designed collector combines in single unit solar energy collection and storage. PCMs are stored in a storage tank, which is located under the collector. A special heat transfer fluid was used to transfer heat from collector to PCM. Exergy analysis, which is based on the second law of thermodynamics, and energy analysis, which is based on the first law, were applied for evaluation of the system efficiency for charging period. The analyses were performed on 3 days in October. It was observed that the average net energy and exergy efficiencies are 45% and 2.2%, respectively.     

能量系统分析优化中排弃火用计价探讨

在火用分析及火用经济分析的基础上,说明了排弃火用与待回收火用的关系,就不同的回收情况,系统地研究了能量系统中排弃火用的计价问题;指出对于能量的逐级回收利用,传统的按物流的序贯分析计价方法并不适用于排弃火用的计价,基于能量系统双子系统模型,提出了当量计价的概念以解决排弃火用的计价问题。最后以催化裂化烟气能量回收方案的演变过程及排弃火用计价的变化表明了此计价方法的实际应用情况。