带压缩空气储能的冷热电联产系统的(火用)分析

对一种带压缩空气储能的冷热电联产系统进行了热力学[火用]分析，得到了各主要部件和整个系统的[火用]损失及[火用]效率的变化规律。分析结果表明：空气透平绝热效率的提高对系统[火用]效率的贡献大于压缩机效率同样提高的功效；在其它参数确定时，存在最佳压比，可使系统的[火用]效率在该条件下达极值；高温换热器是新型冷热电联产系统中产生[火用]损失的主要部件，而循环水量的大小是影响高温换热器[火用]效率的主要因素。     

热力学[火用]及其普遍化表达式的动力学特征

分析了功、热、能和[火用]的物理意义以及与热力学定律的关系，做功和传热是能和[火用]传递与转换的两种途径，从热力学第一定律定义的能量只有相对意义。[火用]是系统相对于环境所具有的做最大有用功的能力，相对于选定的环境，[火用]是系统的状态参量。常规的[火用]计算式是从热力学第一和第二定律导出的结果，从动力学的角度讨论了[火用]及其普遍化表达式的物理含义。[火用]起源于系统与环境的不平衡，如果系统与环境之间存在着某种（或几种）强度量差，在强度量差的推动下系统可能自动地变化到与环境相平衡的状态（寂态），在这样的过程中系统可以对外做功，这种做最大有用功的能力就是系统的[火用]。在能量公设的基础上，[火用]的微分被普遍地表示为强度量差与其共轭的广延量微分的乘积。[火用]的普遍化表达式完整地反映了[火用]的物理含义及其动力学特征，利用能量和[火用]的普遍化表达式导出了[火用]损失的普遍化表达式。     

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。     

燃气初温对燃气轮机[火用]损失的影响分析

基于热力学第二定律,对燃气轮机实际简单循环推导出了燃气轮机各部件[火用]损失的计算公式。通过对某型燃气轮机的定量计算,得出了燃气轮机在不同燃气初温下的[火用]损失。结果表明,燃气初温对燃气轮机的[火用]损失有较大的影响。     

纯低温余热发电系统的炯分析及其主蒸汽参数优化问题

采用[火用]分析的方法,分析计算了纯低温余热发电系统入口余热的[火用]流分布,指出减少出口余热[火用]损和内部换热炯损是提高余热锅炉[火用]回收的关键,并在此基础上分析了主蒸汽压力参数与余热锅炉最大回收[火用]及发电系统最大做功的关系,分析论证其进行优化的原因和必要性,为进一步研究提高纯低温余热发电系统的[火用]回收率提供了参考。     

热泵系统的(火用)分析

用[火用]分析法对热泵供热循环进行了分析，评价了热泵系统的能质利用和损失状况，指出在环境温度、压缩机效率和两器（蒸发器和冷凝器）换热温差一定时，热泵循环存在一个可使循环[火用]效率达到最大的冷凝温度，可在实际中加以利用。     

地埋管换热系统的[火用]分析

建立地埋管地源热泵系统的源侧[火用]分析模型,对地埋管换热系统进行了[火用]分析,研究不同埋深和环境温度的变化对系统[火用]增量的影响。结果表明,合理控制热泵的运行时间可使系统获得较高的[火用]增量;埋深超过100m时,深度的增加对提高[火用]增量来说并不经济。     

HAT循环饱和器工质[火用]计算分析及[火用]效率

饱和器是HAT循环中的关键部件，对其性能的认识关系到整个系统的性能分析。运用[火用]的方法，计算了饱和器工质湿空气和水的堋值，分析了不同参考点的温度和湿度对[火用]值的影响规律，以及物理[火用]和化学扩散[火用]随湿空气温度的变化情况。通过建立饱和器[火用]平衡模型，采用了目的[火用]效率作为饱和器[火用]效率。计算结果表明：湿空气[火用]值随参考点的温度和湿度变化规律为：先减小，直到最低点为零，然后不断增加，[火用]值始终大于（等于）零，并且与参考点参数差距越大，[火用]值越大。当湿空气温度增加，物理[火用]所占比重减少，而化学扩散[火用]的比重增加，在到达一定温度后，化学[火用]大于物理[火用]。     

火电机组回热系统[火用]损分布的通用矩阵方程

根据[火用]平衡方程，首次导出了火电机组回热系统[火用]损分布的通用矩阵方程。利用这一方程可方便地得出不同机组回热系统的[火用]损分布规律，同时这一方程也为建立回热系统乃至整个机组与[火用]损分布通用矩阵方程相关的通用的[火用]分析模型、[火用]经济学分析模型、[火用]经济学优化模型和[火用]经济学故障诊断模型奠定了基础。利用这一方程还可以方便地开发出实时监测回热系统[火用]损分布的计算机程序，为降低机组能耗提供一个实用化的分析工具。图3表1参6     

跨临界CO2内部过冷增压制冷系统高级(火用)分析

为了进一步认识系统的不可逆能量损失,采用高级(火用)分析方法应用于跨临界CO₂内部过冷增压制冷系统,以室外环境温度15.0和30.0℃为例进行计算。结果表明,可避免(火用)损失最主要的部件是高压级压缩机,其次是气体冷却器,优化的重点应放在这些可避免(火用)损失占比较大的部件上;对于整个系统而言,系统(火用)损的绝大部分是可以避免、内因性的,说明系统大部分的不可逆性可以通过优化部件本身来降低。     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Energy and exergy analysis of novel solar bi‐ejector refrigeration system with injector

Energy and exergy balances were done on a novel solar bi‐ejector refrigeration system with R123, whose circulation pump is replaced by an injector. The analysis result of the novel system was compared with that of the original one. The effect of operation condition on system energy efficiency, exergy efficiency and exergy loss was analyzed, and the dynamic performance of a designed solar bi‐ejector refrigeration system was also studied. The comparative results indicate that under the same operating condition, the novel system and the original system have equal energy efficiency, exergy efficiency and exergy loss, and the only difference between them is the exergy losses of the generators and the added injector. The other conclusions mainly include: the solar collector has the largest exergy loss rate of over 90% and for the bi‐ejector refrigeration subcycle, the ejector has the largest exergy loss rate of about 5%; the total exergy loss changes inversely proportional to the evaporation temperature and positively proportional to the condensation temperature; when the other parameters are fixed, there exists an optimum generation temperature, at which the overall energy and exergy efficiencies are both the maximum and the total exergy loss is the minimum. The study points out the direction for optimizing the novel solar bi‐ejector refrigeration system. Copyright © 2009 John Wiley & Sons, Ltd.     

Thermoeconomic optimization of an ice thermal storage system for gas turbine inlet cooling

The gas turbine power output and efficiency decrease with increasing ambient temperature. With compressor inlet air cooling, the air density and mass flow rate as well as the gas turbine net power output increase. The inlet cooling techniques include vapor or absorption refrigeration systems, evaporative cooling systems and thermal energy storage (TES) systems. In this paper the thermoeconomic analysis of ice (latent) thermal energy storage system for gas turbine inlet cooling application was performed. The optimum values of system design parameters were obtained using genetic algorithm optimization technique. The objective function included the capital and operational costs of the gas turbine, vapor compression refrigeration system, without (objective function I) and with (objective function II) corresponding cost due to the system exergy destruction. For gas turbines with net power output in the range of 25-100 MW, the inlet air cooling using a TES system increased the power output in the range of 3.9-25.7%, increased the efficiency in the range 2.1-5.2%, while increased the payback period from about 4 to 7.7 years.     

Energy,exergy and environmental analysis of cold thermal energy storage (CTES) systems

As the air conditioning system is one of the largest contributors to electrical peak demand, the role of the cold thermal energy storage (CTES) system has become more significant in the past decade. The present paper has reviewed the studies conducted on the energy and exergy analysis of CTES systems with a special focus on ice thermal and chilled water storage systems as the most common types of CTES. However, choosing a proper CTES technique is mainly dependent on localized parameters such as the ambient temperature profile, electricity rate structure, and user's habit, which makes it quite difficult and complicated as it depends on many individual parameters. Therefore, it was found that energy and exergy analysis can help significantly for a better judgment. The review paper has shown that the exergetic efficiency analysis can show a more realistic picture than energy efficiency analysis. In addition, the environmental impact and the economic feasibility of these systems are also investigated. It was found that, based on the total exergy efficiency, the ice on coil (internal melt) is known as the most desirable CTES system.     

三级复叠式制冷系统低温级制冷剂的应用分析

为研究三级复叠制冷系统中低温循环制冷剂替代的可行性方案,采用R1150/R170/R717、R50/R170/R717和R14/R170/R717三种工质组合,对三级复叠式制冷系统的高低温循环压缩机的排气温度、压缩机输入功率、COP、热力学完善度、系统的■效率、■损失以及系统中各个部件■损失所占比例随蒸发温度的变化进行热力学分析。研究结果表明:不同蒸发温度下均存在最佳中间循环冷凝温度,使COP值最大。蒸发温度由-100.0℃升高到-80.0℃时,R1150/R170/R717的■损失最小,COP、热力学完善度和■效率最大。R1150/R170/R717的COP由0.60增大到0.82。R1150/R170/R717的COP比R14/R170/R717的COP高3.47%～4.49%。主要的■损失部件是冷凝器,冷凝器的■损失所占比例随蒸发温度的升高而升高。推荐在三级复叠式制冷系统中采用R1150/R170/R717制冷剂组合方案,研究结果为三级复叠式制冷系统工质组的选择提供理论依据。     

中温地热能驱动的跨临界有机朗肯-蒸气压缩制冷系统的火用分析

建立中温地热能驱动跨临界有机朗肯−蒸气压缩制冷系统的火用分析热力学模型,采用R143a作为系统循环工质,探讨膨胀机入口压力、地热流体进口温度、冷凝温度、蒸发温度对火用效率的影响规律,分析系统各个部件的火用损失。计算结果表明：合理的膨胀机入口压力应该小于1.8倍临界压力;存在最佳的地热流体进口温度使得系统的火用效率最大;降低冷凝温度和提高蒸发温度都可以提高?效率,但需要增加换热器等效换热面积作为代价;冷凝器、发生器、膨胀机、节流阀、压缩机、蒸发器、工质泵的火用损失依次降低;随着地热流体进口温度升高,冷凝器及发生器的火用损失所占的比例增大,其它部件的火用损失对应的比例则降低。本文可以为跨临界有机朗肯−蒸气压缩制冷系统的设计提供依据。     

Exergy analysis,parametric analysis and optimization for a novel combined power and ejector refrigeration cycle

A new combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the ejector refrigeration cycle. This combined cycle produces both power output and refrigeration output simultaneously. It can be driven by the flue gas of gas turbine or engine, solar energy, geothermal energy and industrial waste heats. An exergy analysis is performed to guide the thermodynamic improvement for this cycle. And a parametric analysis is conducted to evaluate the effects of the key thermodynamic parameters on the performance of the combined cycle. In addition, a parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The results show that the biggest exergy loss due to the irreversibility occurs in heat addition processes, and the ejector causes the next largest exergy loss. It is also shown that the turbine inlet pressure, the turbine back pressure, the condenser temperature and the evaporator temperature have significant effects on the turbine power output, refrigeration output and exergy efficiency of the combined cycle. The optimized exergy efficiency is 27.10% under the given condition.     

An exergy analysis of a traditional compressed air energy storage system

压缩空气储能技术是具有较大发展前景的大规模储能技术之一,具有广阔的发展前景。使用Aspen Plus软件以传统压缩空气储能系统为例进行流程模拟,运用分析方法对模拟结果进行热力性能分析。分析结果表明,燃烧室的损失是系统各设备损失中最大的。同时还对压缩空气储能系统各个组成部件的运行效率与储能系统的损失之间的关系进行了敏感性分析,分析结果表明,对系统效率影响最大的参数为燃烧室效率,最小的参数为膨胀透平绝热效率。     

供冷系统能耗评价模型及应用

随着人民生活水平提高,供冷系统日益普及。受全球气候变暖和能源资源短缺问题影响,供冷系统能耗控制日益受到广泛关注。为科学表征供冷系统能源消耗状况,将供冷系统划分为六个子系统,从总能系统层次上给出了适合于各类供冷系统的广义化的能耗评价一般模型。在此基础之上,结合单耗分析方法,提出了供冷系统能耗的定量计算方法。采用了热力学第一定律、热力学第二定律分析,对供冷过程的热力学本质、冷量?、供冷能力等方面展开研究,系统阐述了供冷系统的理论节能极限及理论最低能耗,并立足总能系统对供冷过程的理论极限－可逆供冷作出了说明。在北京市目前设计标准下,供冷系统理论最低燃料单耗为0.82kg/GJ,当前供冷系统能耗水平（25.27 kg/GJ）与之相比,节能潜力甚大。为验证所构建的供冷系统能耗评价一般化模型,结合北京市通州区供冷系统的实施方案,对分散电制冷、集中电制冷、分散热制冷、集中热制冷四个基本类型的供冷模式进行了实例计算分析,并与四种模式的?分析计算结果进行了比较,结果显示：所提能耗模型与?分析结果一致,电制冷燃料单耗低于热制冷,分散制冷燃料单耗低于集中制冷,集中热制冷能耗较高,应慎重发展。所提出的能耗分析评估模型为各种类型供冷系统的一般化对比评估提供了理论分析方法,同时可为城市供冷系统的规划设计提供参考。