低Reynolds数空气来流正庚烷液滴蒸发过程熵产特性  

Entropy production characteristics through n-heptane evaporation in low Reynolds number incoming air flow

作　　者：郭洋裕 张昊春[1] 于海燕[1] JIN Yan 李垚[3] 

机构地区：[1]哈尔滨工业大学能源科学与工程学院,黑龙江哈尔滨150001 [2]Institute of Thermo-Fluid Dynamics,Hamburg University of Technology [3]哈尔滨工业大学复合材料研究所,黑龙江哈尔滨150001

出　　处：《化工学报》2014年第6期1971-1977,共7页CIESC Journal

基　　金：国家自然科学基金项目(51006026;91216123);中央高校基本科研业务费专项资金(HIT.NSRIF.2012.072)~~

摘　　要：车用内燃机、航空发动机燃料的主要成分为正庚烷液体。液体燃烧属于扩散型燃烧,燃料先雾化成油雾,然后蒸发,燃油蒸气在气态扩散火焰中燃烧。油雾蒸发是液体燃烧中的重要过程,是决定液体燃烧的燃烧速率的关键步骤。建立了一个二维准稳态的液滴蒸发数值模型,分析了液滴蒸发的熵产,推导出了三维笛卡尔坐标系下的传质熵产公式。基于Fluent软件进行了数值模拟,结果显示低Reynolds数空气来流中的液滴蒸发过程的熵产主要由导热熵产组成,且液滴蒸发越容易,相对总熵产越小,从热力学角度来看其液滴蒸发过程更优。The main component of vehicle internal combustion engine and aircraft engine fuel is n-heptane. Combustion of liquid fuel belongs to diffusive combustion. The combustion process is composed of atomization, evaporation and diffusive combustion, and the evaporation process is vitally important, which critically determines the combustion speed of fuel droplet. Hence it is essential to optimize this process. In this paper, the evaporation of n-heptane droplet was evaluated from the perspective of second law of thermodynamics. A two-dimensional quasi-steady state model of the evaporation process was proposed, and the entropy production of the process was solved by integration of the volumetric entropy production rate in the whole domain. The viscous, conductive, mass transfer entropy production was investigated and compared, with the help of viscous and conductive entropy production rate equations reported in literatures and mass transfer entropy production rate equation derived in this paper, after numerical simulation of the evaporation process with Fluent software. Also, the relative total entropy production was defined. Conductive entropy production was the main part of the total entropy production of n-heptane evaporation in the low-Re air flow. With increasing Re and temperature of airflow, relative total entropy production decreased. In other words, the evaporation process produced less entropy relatively and it became＆amp;nbsp;easier, which from a thermodynamics perspective was optimal.

关 键 词：雾化燃烧 液滴蒸发 传质 热力学 数值模拟 熵产 

分 类 号：TK124[动力工程及工程热物理—工程热物理]