Infrared Evaporative Absorption and Condensative Emission in Water

水中红外蒸发吸收和冷凝发射

• 批准号: 1062361
• 负责人: M Q Brewster
• 金额: $ 33.34万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1062361&HistoricalAwards=false
• 关键词: Infrared; Evaporative; Absorption; Condensative; Emission

1062361BrewsterAbstract The objective of this project is to investigate infrared radiation emission and absorption associated with first-order, vapor-liquid and vapor-solid phase transitions in water. Water undergoing condensation and evaporation plays a vital role in many engineering systems as well as in the environment. Heat exchangers are pervasive in society and water condensation, vaporization, sublimation and deposition are critically important in the performance of these devices. Drying is another important industrial process involving water vaporization that is very energy intensive. In the environment water plays a crucial thermal regulation role and its phase changes have a significant effect on Earth's energy balance through latent heat effects. It is also well known that water, in all three phases, plays an important role in atmospheric and surface radiative transfer via volumetric (single-phase) emission, absorption, and scattering. What is not well recognized is that vapor-liquid and vapor-solid water phase-transitions also may play a potentially critical role in surface and atmospheric radiative transfer. In spite of extensive knowledge of water's bulk, volumetric infrared properties, surface radiative properties associated with first-order phase transitions are almost unrecognized. In this study both measurements and modeling of phase-change radiation involving vapor and condensed-state transitions will be conducted. A laboratory-scale test chamber will be constructed and used to measure infrared emission and absorption by water droplets tens of microns and smaller in size undergoing vapor-liquid phase transition. The closed chamber will operate isobarically under steady-state and transient heating/cooling conditions. Surface (phase-change) emission/absorption will be delineated from volumetric emission/absorption by analytic data reduction techniques including Monte Carlo methods. A unified molecular model will be developed covering solid-, liquid-, and vapor-states that describes both new surface radiative phase-change properties and volumetric (single-phase) radiative properties. This study has intellectual merits at levels ranging from fundamental, scientifically oriented to engineering oriented. New knowledge will be generated about radiative phase- transitions for one of the most important substances on the planet. The infrared emission measurements will generate new knowledge about liquid-vapor radiative phase transitions of water for both condensation and vaporization. These measurements will be used to develop a model for liquid-water structure. At the engineering level, new data and a mathematical model for infrared emission and absorption by water will be developed. This study will also have broader impacts, ranging from individuals to society at-large. At the individual level this study will most immediately affect the education and career of graduate and undergraduate students. Locally, workshops will be conducted for K-12 students on water properties, phase-change heat transfer, and global climate change. At the engineering level the radiative phase-transition findings obtained herein will allow a better fundamental understanding of energy transfer in heat exchanger and drying equipment. At a larger, societal level, these findings may open a door to improved microphysical modeling of atmospheric energy transfer processes. The ultimate broad impact of this project will be better understanding of the fundamental thermophysical properties of our industrial society's primary thermal regulating fluid and Earth's principal greenhouse gas: water.

摘要本课题的目的是研究水的一阶相变、气液相变和气固相变与红外辐射发射和吸收的关系。水经过冷凝和蒸发在许多工程系统和环境中起着至关重要的作用。热交换器在社会中无处不在，水的冷凝、蒸发、升华和沉积对热交换器的性能至关重要。干燥是另一个重要的工业过程，涉及水的蒸发，这是非常耗能的。在环境中，水起着至关重要的热调节作用，其相变通过潜热效应对地球的能量平衡有重要影响。众所周知，水在这三个阶段中，通过体积（单相）发射、吸收和散射，在大气和地表辐射传输中起着重要作用。没有得到充分认识的是，气-液和气-固水相变也可能在地表和大气辐射传输中起潜在的关键作用。尽管对水的体积、体积红外特性有广泛的了解，但与一阶相变相关的表面辐射特性却几乎不为人所知。在本研究中，将对涉及蒸汽和冷凝态转变的相变辐射进行测量和建模。将建立一个实验室规模的测试室，用于测量几十微米及更小尺寸的水滴在气液相变过程中的红外发射和吸收。封闭腔室将在稳态和瞬态加热/冷却条件下等压运行。表面（相变）发射/吸收将通过包括蒙特卡罗方法在内的分析数据还原技术从体积发射/吸收中描绘出来。将开发一个统一的分子模型，涵盖固体、液体和蒸汽状态，描述新的表面辐射相变特性和体积（单相）辐射特性。这项研究在从基础的、科学的到工程的各个层面上都具有智力上的优点。关于地球上最重要的物质之一的辐射相变将产生新的知识。红外发射测量将产生关于水的冷凝和蒸发的液-汽辐射相变的新知识。这些测量结果将用于开发液态水结构模型。在工程层面，将开发新的数据和水的红外发射和吸收的数学模型。这项研究还将产生更广泛的影响，从个人到整个社会。在个人层面上，这项研究将最直接地影响研究生和本科生的教育和职业生涯。在当地，将为K-12学生举办关于水性质、相变传热和全球气候变化的研讨会。在工程水平上，本文获得的辐射相变结果将使人们对热交换器和干燥设备中的能量传递有更好的基本理解。在更大的社会层面上，这些发现可能为改进大气能量转移过程的微物理建模打开了一扇门。这个项目的最终广泛影响将是更好地理解我们工业社会的主要热调节流体和地球上主要的温室气体：水的基本热物理性质。