考虑环境成本的能量系统(火用)经济学分析模型

随着可持续发展战略的实施,对传统的(火用)经济学提出了新的挑战。本文在传统佣经济学分析的基础上,将环境成本引入到(火用)经济学分析中,首先提出了“广义子系统”的概念,建立了包括(火用)环境成本平衡在内的各种平衡方程;在系统生产结构的描述中,将系统中的(火用)流划分成外界输入(火用)流、内部(火用)流以及向外界输出(火用)流三类,最终建立了以矩阵形式表示的各种平衡方程,用于求解系统中各股(火用)流的单位(火用)成本、单位(火用)经济成本、单位环境成本、单位综合(火用)经济成本等性能参数。最后针对某国产200MW机组进行了实例计算。     

基于(火用)概念的能量系统环境效应评价和建模

基于环境是稀缺资源,提出环境效应的(火用)评价策略及其废物(火用)费用估算方法,引入了环境损害因子、环境污染率及环境损害函数的概念。按照能量转换、能量回收子系统系统的(火用)流变化与环境污染特征,建立了能量系统环境(火用)经济三子系统分析优化模型,并分别给出了各子系统环境(火用)经济优化的目标函数。     

二元溶液的及溴化锂水溶液的-浓度图

本文提出二元溶液(火用)值计算的一般方法。计算了溴化锂水溶液的(火用)值,绘制了该溶液的(火用)-浓度图。文中还给出了溴化锂水溶液化学(火用)与浓度的拟合关系式。 一、溶液的化学(火用) 由于溶液的浓度或成分有变化,在确定溶液(火用)值时必须考虑溶液的化学(火用)。给定状态和浓度下溶液的(火用)是物理(火用)与化学(火用)之和。在环境温度T_0和压力P_0下系统与环境由     

灰体辐射(火用)分析

以两个无穷大平板组成的系统为例,本文利用Karlsson和Candau对光谱辐射(火用)的定义,通过对系统内光谱辐射(火用)强度的数值求解,获得了灰体光谱辐射(火用)强度随波长和发射率的变化规律,比较了光谱辐射强度、光谱辐射(火用)强度的峰值所对应的波长与发射率的关系,最后从宏观热力学理论分析光谱辐射(火用)强度的定义式.结果表明光谱辐射(火用)强度的峰值波长和光谱辐射强度的峰值波长不一致,光谱辐射能有用度随发射率的增大而增大,光谱辐射(火用)损失与系统熵产间的关系满足宏观热力学中的Gouy-Stodola理论.     

太阳能动力系统的热力学分析和优化问题

一、太阳能集热器的(火用)分析 太阳能动力系统大多采用双流体循环,如图1。一次系统中的(火用)差为可以定义集热器的(火用)系数ψ为     

R22(CHF_2CL)焓图

不少作者对常用工质绘制过(火用)焓图。本文利用Oguchi等人提出的状态方程,算出并绘制了R 22(火用)焓图(SI制),并给出两种不同环境温度时使用本图的(火用)修正曲线。 一、R22(火用)焓图的编制 R 22(火用)焓图以稳定流动系统工质比焓(火用)e为纵坐标,以比焓h为横坐标。焓(火用)e的定义式为     

基于(?)分析的空分流程对比研究

以内、外压缩空分流程为对象,通过AspenPlus模拟计算获得系统总(火用)损失,(火用)效率及压力(火用)、温度(火用)、跑冷(火用)、分离(火用)占设备(火用)损失的比例,探讨两类流程的区别。研究发现:压缩、精馏及换热设备损失是空分系统(火用)损失的主要来源;内压缩流程主换热器、过冷器的传热损失比例大于外压缩流程;相对传统的外压缩流程,内压缩流程在生产液体及高压产品方面表现更优。最后探讨了一种基于空分流程产品冷(火用)与膨胀节流过程产生冷量的变化关系来进行流程比较的方法。     

考虑环境的能量转换系统环境(火用)经济建模与优化

按照能量转换系统中(火用)流及废物流变化特征,提出了增设废物处理子系统进行系统排放废物的达标处理,并将整个系统划分为能量转换主子系统及废物治理附属子系统.给出了两个子系统各自的同时考虑热力学、经济学、环境三个目标的环境(火用)经济优化目标及相应的约束条件;提出了能量转换系统的环境(火用)经济分解协调优化策略,在子系统分别优化的基础上协调,达到系统全局的优化.     

结合ORC和ARC的中温余热回收系统

中温余热回收过程中传热温差大,系统(火用)效率较低,本文提出一种结合有机朗肯循环和单效吸收式制冷系统的中温烟气余热回收系统。利用热力学第一定律和第二定律对系统建立了数学模型,分析了新系统中有机朗肯循环蒸发温度、冷凝温度等参数对系统性能的影响。同时对系统各主要部件进行了(火用)分析,并与双效溴化锂吸收式制冷系统进行了比较,通过T-Q图分析了新系统及参考系统的换热过程。结果表明新系统的(火用)损失从139.19 kW降低到93.18 kW,(火用)损失减少机理在于换热温差降低。     

复杂系统能量传递-转换模型(Ⅰ)

(火用)效率是以(火用)的概念进行系统分析和综合的目标函数。它的定义是否正确和合理,将直接关系到这些工作的结果。 本文将复杂的生产系统看成一个复杂的能量传递-转换系统。如何正确和合理定义复杂的能量传递-转换系统(火用)效率,是一个尚未解决的问题。本文用文献[1]提出的“能量单元”概念,运用系统工程的方法,从考察能量单元间连接的关系上,提出了几种典型的复杂系统能量传递-转换模型及其(火用)效率定义式,由此明确节     

界面常质量流湍流（火用）传递

导出了常温下充分发展湍流传递方程组,依此研究了界面常质量流管内湍流传递,研究了由于粘性耗散、径向和轴向传质不可逆性引起的损率随流体性质、边界条件及空间位置的变化规律,分析了不同地点由于不同过程产生损失的机理.对单位长度的总损率计算表明,对给定的流体单位长度总损率是传质单元几何参数、边界条件和雷诺数的多元函数,通过损率最小化可设计和优化传质单元.     

Exergy Analysis of a Bio-System: Soil–Plant Interaction

This paper explains a thorough exergy analysis of the most important reactions in soil–plant interactions. Soil, which is a prime mover of gases, metals, structural crystals, and electrolytes, constantly resembles an electric field of charge and discharge. The second law of thermodynamics reflects the deterioration of resources through the destruction of exergy. In this study, we developed a new method to assess the exergy of soil and plant formation processes. Depending on the types of soil, one may assess the efficiency and degradation of resources by incorporating or using biomass storage. According to the results of this study, during different processes from the mineralization process to nutrient uptake by the plant, about 62.5% of the input exergy will be destroyed because of the soil solution reactions. Most of the exergy destruction occurs in the biota–atmosphere subsystem, especially in the photosynthesis reaction, due to its low efficiency (about 15%). Humus and protonation reactions, with 14% and 13% exergy destruction, respectively, are the most exergy destroying reactions. Respiratory, weathering, and reverse weathering reactions account for the lowest percentage of exergy destruction and less than one percent of total exergy destruction in the soil system. The total exergy yield of the soil system is estimated at about 37.45%.     

An Exergoeconomic Analysis of a Gas-Type Industrial Drying System of Black Tea

The performance evaluation and optimization of an energy conversion system design of an energy intensive drying system applied the method of combining exergy and economy is a theme of global concern. In this study, a gas-type industrial drying system of black tea with a capacity of 100 kg/h is used to investigate the exergetic and economic performance through the exergy and exergoeconomic methodology. The result shows that the drying rate of tea varies from the maximum value of 3.48 g_water/g_{dry matter} h to the minimum 0.18 g_water/g_{dry matter} h. The highest exergy destruction rate is found for the drying chamber (74.92 kW), followed by the combustion chamber (20.42 kW) in the initial drying system, and 51.83 kW and 21.15 kW in the redrying system. Similarly, the highest cost of the exergy destruction rate is found for the drying chamber (18.497 USD/h), followed by the combustion chamber (5.041 USD/h) in the initial drying system, and 12.796 USD/h and 5.222 USD/h in the redrying system. Furthermore, we analyzed the unit exergy rate consumed and the unit exergy cost of water removal in different drying sections of the drying system, and determined the optimal ordering of each component. These results mentioned above indicate that, whether from an energy or economic perspective, the component improvements should prioritize the drying chamber. Accordingly, minimizing exergy destruction and the cost of the exergy destruction rate can be considered as a strategy for improving the performance of energy and economy. Overall, the main results provide a more intuitive judgment for system improvement and optimization, and the exergy and exergoeconomic methodology can be commended as a method for agricultural product industrial drying from the perspective of exergoeconomics.     

土壤源热泵系统的火用成本分析

在对火用分析与经济学原理研究的基础上,利用火用成本分析方法,建立了土壤源热泵系统的(火用) 成本分析模型.以实际的建筑空调系统为背景,运用所建火用成本分析模型与能量成本分析方法,对土壤源热泵系统与风冷热泵系统进行了对比分析计算,并以空气源热泵为基础对土壤源热泵进行了敏感性分析.对土壤源热泵的实际应用具有指导意义.     

The exergy carry-over index for a utility system

An exergy analysis has been conducted for the utility system of an integrated sugar cane processing plant. A 22 MW boiler supplies steam to five turbines. The availability or exergy analysis establishes the amount of chemical and thermal energy that can possibly be transformed into work. Of the 100 units of available energy from the fuel, only 62.2 units are exergy. The steam cycle absorbs 60.3 energy units, of which 21.0 are exergy. The exergy carry-over index for the boiler is 0.56. The steam transfers to the turbines 2.2 energy units, all of which are exergy. The index is 2.86 for the steam cycle and 1.61 for the combined installation.     

Comparaison de deux approches d'optimisation. Application à une thermopompe

Comparison between two optimization approaches. Application to a heat pump. An energy flux consists of two parts; an available part, the exergy, and a non-available part, the anergy. The functional diagram of an energetic system is a schematic representation of fluxes for these two compounds. On this diagram, we define the products and ressources of exergy and anergy for each unit of the system as interactions with the external environment and/or with an internal network using two loops: an exergy loop and an anergy loop. This internal circuit could be represented by a server managing the use of exergy and anergy by the various units of the system. We associate to the exergy and anergy fluxes, unit costs defined through an approach called decomposition [1]. This study is concerned with the comparison of results when optimization is based on an objective function, that is one side the investment cost of the system and on the other side the coefficient of performance (COP). In both cases, the work downstream consists in optimizing the unit cost of the main product of each component using the decomposition approach. We will compare the COP, the investment cost, the annual cost and the thermodynamic states of the system.     

Chemical and Mechanical Aspect of Entropy-Exergy Relationship

The present research focuses the chemical aspect of entropy and exergy properties. This research represents the complement of a previous treatise already published and constitutes a set of concepts and definitions relating to the entropy–exergy relationship overarching thermal, chemical and mechanical aspects. The extended perspective here proposed aims at embracing physical and chemical disciplines, describing macroscopic or microscopic systems characterized in the domain of industrial engineering and biotechnologies. The definition of chemical exergy, based on the Carnot chemical cycle, is complementary to the definition of thermal exergy expressed by means of the Carnot thermal cycle. These properties further prove that the mechanical exergy is an additional contribution to the generalized exergy to be accounted for in any equilibrium or non-equilibrium phenomena. The objective is to evaluate all interactions between the internal system and external environment, as well as performances in energy transduction processes.     

Optimization of the precooler of hydrogen fueled gas turbine

Liquid hydrogen is expected to be an alternative to fossil fuel. In this study, the gas turbine cycle with the precooler and hydrogen turbine is proposed to utilize the cryogenic exergy contained in the liquid hydrogen effectively. Since the geometry of the precooler greatly affects the performance of the system, it is optimized to give the maximum specific work output and/or the maximum exergy efficiency. In addition, the mass flow rate of hydrogen in the precooler is not restricted to that used for combustion. The ratio α of hydrogen mass flow rate is introduced as a measure indicating the precooling effect. The surplus hydrogen is assumed to be consumed in the external gas turbine system. The effect of α on the output and the exergy efficiency of the total system is made clear.     

Exergy Analysis Using a Theoretical Formulation of a Geothermal Power Plant in Cerro Prieto,México

The purpose of this research is the calculation of the exergy destruction of the single-flash and double-flash cycles of a geothermal power plant located on the ladder of the 233 m Cerro Prieto volcano, on the alluvial plain of the Mexicali Valley, Mexico. The methodology developed in this research presents thermodynamic models for energy and exergy flows, which allows determining the contribution of each component to the total exergy destruction of the system. For the case-base, the results indicate that for the single-flash configuration the efficiency of the first and second law of thermodynamics are 0.1888 and 0.3072, as well as the highest contribution to the total exergy destruction is provided by the condenser. For the double-flash configuration, the efficiency of the first and second law of thermodynamics are 0.3643 and 0.4983. The highest contribution to the total exergy destruction is provided by the condenser and followed by the low-pressure turbine.     

Second law optimization of a latent heat storage system with PCMS having different melting points

The exergy efficiency, as well as the charging and discharging rates, in a latent heat storage system can be improved by use of the PCMs having different melting points. The melting point distribution of the PCMs has substantial effects on the exergy efficiency. The optimum melting point distribution of the PCMs has been estimated from numerical simulations and also from simple equations. The fast charging or discharging rate leads to high exergy efficiency.