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.

1062361BrewsterAbstract 该项目的目标是研究与水中一级、汽-液和汽-固相变相关的红外辐射发射和吸收。 经历冷凝和蒸发的水在许多工程系统以及环境中起着至关重要的作用。 热交换器在社会中普遍存在，水的冷凝、汽化、升华和沉积对于这些设备的性能至关重要。 干燥是另一个重要的涉及水蒸发的工业过程，该过程非常耗能。 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产生重大影响。 众所周知，水在所有三相中通过体积（单相）发射、吸收和散射在大气和表面辐射传输中发挥着重要作用。尚未得到充分认识的是，汽-液和​​汽-固水相变也可能在表面和大气辐射传输中发挥潜在的关键作用。 尽管人们对水的体积、体积红外特性有了广泛的了解，但与一级相变相关的表面辐射特性几乎未被认识到。 在这项研究中，将进行涉及蒸气和凝聚态转变的相变辐射的测量和建模。 将建造一个实验室规模的测试室，用于测量数十微米或更小尺寸的水滴经历汽-液相变时的红外发射和吸收。 封闭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缩减技术与体积发射/吸收进行区分。将开发一个涵盖固态、液态和气态的统一分子模型，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、科学到工程的各个层面上都具有智力价值。关于地球上最重要物质之一的辐射相变的新知识将会产生。红外发射测量将产生关于水的冷凝和汽化的液-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，将开发关于水的红外发射和吸收的新数据和数学模型。 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。在当地，将为 K-12 学生举办有关水特性、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发现将有助于更好地基本了解热交换器和干燥设备中的能量传递。在更大的社会层面上，这些发现可能为改进大气能量传递过程的微物理模型打开一扇大门。该项目的最终广泛影响将是更好地了解我们工业社会的主要热调节流体和地球主要温室气体：水的基本热物理特性。