【作者】 王厉；

【导师】 李念平；

【作者基本信息】 湖南大学 ， 供热、供燃气、通风及空调工程， 2012， 博士

【摘要】 在资源日趋紧张，环境保护压力不断增大的当今社会，节能减排已经成为很多国家、阶层和团体之间的共识。由于暖通空调系统在建筑能耗中占有很大的比例，因此对暖通空调系统的能耗问题展开研究，发展和应用新的节能技术就成为当今节能减排中的一项具体的重要工作。对暖通空调系统的研究过程中，通常采用能量分析方法，它虽然具有直观、简便的特点，却不能描述系统中存在的各种不可逆损失，因而对于系统的不合理用能状况难以进行量化、评价，为此在暖通空调系统中利用（火用）分析方法进行研究成为近年来的一个重要发展方向。然而，相对于暖通空调系统所涵盖的广大范围而言，当前的（火用）分析研究在某些方面上还很少涉及，如自然通风系统、溶液除湿系统以及一些新型吸收式制冷/制热系统，另外，目前的（火用）分析往往针对具体的实际系统，研究结果受具体因素影响而缺乏普遍性。因此，本文基于（火用）分析方法，针对暖通空调系统，着力于在以上两个方面开展研究，具体涉及了自然通风系统、蒸发冷却系统、溶液除湿系统、吸收式制冷/热泵系统以及吸收压缩式制冷/热泵系统的（火用）传递情况、运行工况和（火用）效影响因素，拓展了对暖通空调系统研究的广度，同时通过基于（火用）方法的热力学分析，揭示了各系统运行过程中所表现出的普遍规律和实质，也为实际系统的评价、运行及改进提供了理论指导。论文的主要研究工作和成果有：(1)详细介绍了（火用）分析中的一些重要基本概念，能量及（火用）传递过程中的动力学微分方程及其物理意义，进一步介绍了普遍化形式的能量及（火用）传递方程，重点阐述了不同表达方式下能量及（火用）传递过程的区别和联系，为利用（火用）分析方法研究暖通空调系统阐明了理论基础。(2)通过建立一维稳态（火用）平衡方程，以一带中庭的高层建筑为对象，分析了自然通风系统中的（火用）传递、驱动机制和（火用）效表现，阐明了自然通风和机械通风在能量分析角度和（火用）分析角度上存在的差异及其原因，分析了内外温差对自然通风系统（火用）效的影响，指出其中存在（火用）优化机会，进一步分析了利用太阳能进行光热转换驱动的自然通风系统和进行光电转换驱动的机械通风系统的（火用）效差异，指出光电转换具有更高（火用）效，为太阳能驱动通风系统的合理利用提供了理论指导。(3)通过分析湿空气（火用）和水（火用）的各项构成及其物理意义，提出将水（火用）用蒸发相变过程所涉及的饱和蒸汽（火用）和潜热（火用）来表示，从而将水（火用）计算与热湿处理过程中常见的水的相变过程联系起来，进一步研究了水（火用）、潜热（冷）（火用）以及蒸汽（火用）之间随温度变化的相互关系，划分出3个特征区域并阐明了各区域的（火用）传递特点，分析了直接蒸发冷却系统和简接蒸发冷却系统的（火用）效，指出在直接和间接蒸发冷却系统中都存在（火用）优化机会。通过建立计算模型并利用实验结果进行验证，对直接蒸发式冷却塔的（火用）传递过程以及（火用）效随水空比、冷却塔热效率的变化情况进行了详细分析。(4)从（火用）分析角度探讨了空调系统（火用）负荷的构成及其物理意义，通过动态能耗模拟方法研究了各类空调（火用）负荷的变化规律，分析了空调（火用）负荷与空调负荷的差异和原因，比较了风冷空调系统和水冷空调系统中空调（火用）负荷的变化规律。提出对空调系统热、湿处理过程进行单独（火用）评价的概念及方法，以某一次回风空调系统的夏季工况为例，阐明了该独立评价方法的应用过程，这对于在空调系统中促进热、湿独立处理技术的应用具有较大意义。(5)对溶液除湿系统的运行工况进行划分，研究其在各工况下的运行特点及其（火用）传递情况。通过建立（火用）平衡方程，研究了除湿温度、环境温度和环境水蒸汽分压力对溶液除湿系统（火用）效的影响规律，通过与冷凝除湿方式比较，指出溶液除湿系统的效率只在某些工况下才具有相对优势。进一步在普通溶液除湿系统基础上，提出双效溶液除湿系统，并对其进行了（火用）分析，阐明了双效系统相对于原系统的优越性，为双效系统的应用提供了初步的理论依据。(6)以吸收制冷/热泵系统为研究对象，分析了吸收式制冷系统、第一类吸收式热泵系统、第二类吸收式热泵系统的（火用）平衡、（火用）传递及运行工况，分析了运行参数对各系统（火用）效的影响，从（火用）方法角度揭示了这些系统中所表现出的普遍规律，对于理解、评价及改进实际系统具有指导意义。(7)对吸收压缩式制冷/热泵系统进行（火用）分析，研究了它们的（火用）平衡、工况划分及影响因素，所得结论对于认识、研究和评价实际系统具有普遍意义，重点提出了吸收压缩式双效第二类热泵系统、吸收压缩式双温第二类热泵系统和吸收压缩式双温双效第二类热泵系统等新的系统型式并进行（火用）分析，丰富了吸收压缩式系统型式，为其实际应用奠定了理论基础。更多还原

【Abstract】 Energy saving and emission reduction has become common understanding ofmany countries, classes and groups as the relations between human being andresources and environment are getting tension. It is considered that development andapplication of new energy saving technology in HVAC systems which take up a greatproportion in building energy consumption is very important. Generally, HVACsystems are studied by energy analysis method, which is simple and easy tounderstand but is not an effecitive method to describe different irreversible losses.Thus, the exergy analysis method has attracted more and more attentions in nowadaysand obtained many achievements. However, the past researches on this filed areemphasized in concret systems, the performance of the HVAC systems in the meaningof thermodynamic limit is negnected and have some deficienceies in the application ofexergy analysis. Therefore, this paper conducted thorough research intobuoyance-driven ventilation, evaporative cooling process, air conditioning exergy load,ideal liquid dessicant cycles, ideal absorption refrigeration/heatpump cycles and idealabsorption-compression refrigeration/heat pump cycles in respects of exergy transfer,running conditions and impact factors of exergy efficiency by exergy analysis methodand empasized on the research in the meaning of thermodynamic limit so as tohighlight the university of results and provides a theoretical guidance for assessmentand improvement of real systems. The main research work and its conclusions areintroduced as follows:(1) The basic concepts of exergy analysis are introduced, as well as the dynamicdifferential equations in energy and exergy transfer process and their physicalmeanings, it introduced the general energy and exergy transfer equations, mainlydiscussing the differences and connections, to elucidate the theoretical foundation ofexergy analysis method used for HVAC systems.(2) A model of buoyancy-driven ventilation in a high building with an atrim isanalyzed in respects of exergy transfer, driving mechanism and exergy performance byexergy balance equations. It expouds the differences in buoyancy-driven ventilationand mechanical ventilation from energy and exergy concepts, analyzes the effect oftemperature difference between the atrim and the environment on exergy efficiency,points out the exergy optimization opportunity. Moreover, the ventilation systems driven by photothermal conversion and photoelectric conversion of solar energy arecompared on exergy efficiency with a result that the photoelectric conversion is moreefficient, providing a theoretical guidance for rational utilazation of solar-drivenventilation systems.(3) By analyzing the exergy compositions and physical meanings of moist airand water, it puts forward an expression of water exergy which involves water vaporexergy and latent heat exergy of water for relating the water exergy calculation withthe phase change process in air conditioning systems. Moreover, the relations betweenexergy of water, water vapor and latent heat on different temperature are studied andthree feature regions are outlined with different characteristics of exergy transfer.After analyzing the ideal direct and indirect evaporation cooling systems, it shows thatthere exist exergy optimization opportunities in both systems. The exergy transfer andthe effects of water-to-air ratio and thermal efficiency on exergy efficiency are alsodiscussed in detail by theoretical calculation for the counter-flow cooling tower.(4) The compositions and physical meanings of various air conditioning exergyloads have been investigated through exergy analysis, and the variations of differentair conditioning exergy load are studyed by dynamic energy-consuming simulationmethod. The differences and reasons between exergy load and air conditioning loadare analyzed, and the effects of air cooled mode and water cooled mode on airconditioning exergy loads are made. The method to evaluate the air conditioningprocess by exergy analysis based on independent temperature and humidity contry isput forward, and a primary return air system in summer condition is analyzed forexample, showing the application value of this independent evaluation method,promoting the development of temperature and humidity control technology.(5) An ideal liquid desiccant dehumidification system has been built based on theideal liquid desiccant cycle, in which the running conditions are divided, and theoperation characteristics and the exergy transfer under various running conditions arestudied which have realistic guiding significance to the operation of practical systems.It discusses the effects of dessicant temperature, the environment temperature and thewater vapor pressure on the exergy efficiency, and indicates that the efficiency ofliquid dessicant system has relative advantage only under certain conditions whencomparing with the condensation dessicant systems. A double-effect liquid dessicantsystem is further proposed, and corresponding exergy analysis is done. It shows thatthe newly presented system is always superiorious over the original system, providingpreliminary theoretical foundation for application of the double-effect system. (6) The ideal absorption refrigeration system, the ideal typeⅠ/typeⅡabsorptionheat pump systems based on the ideal liquid cycle are studied by exergy analysis, theexergy transfer, exergy balance and running conditions of these systems discussed, aswell as the effects of operation parameters, the exergy performance of these systemsare discussed from from the view of thermodynamic limit with a guiding significancefor further understanding, evaluating and improving real systems.(7) A study focusing the absorption-compression refrigeration/heat pump systemsin respects of exergy balance, running conditions and impact factors is carried out,which is expected to be universally significant for further understanding andevaluating practical systems. The typeⅡ absorption-compression double effect heatpump system, typeⅡ absorption-compression double temperature heat pump systemand typeⅡ absorption-compression double-temperature double effect heat pumpsystem are presented and analyzed from exergy concept, these systems enrich thetypes of the absorption-compression systems and the discusses lay a theritical basis forpractical applications.更多还原