干燥过程中脉动气流与物料间的热量传递特性  

Heat Transfer Between Materials and Unsteady Airflow from a Helmholtz Type Combustor

作　　者：陈有庆[1] 刘相东[1] 

机构地区：[1]中国农业大学,北京100083

出　　处：《干燥技术与设备》2007年第2期89-92,共4页

摘　　要：脉动燃烧装置用于干燥过程时具有热效率高和污染物排放量少等优点,但由于目前对其热质传递的特性缺乏深入的了解,限制了此类干燥器的广泛应用。为了深入了解脉动燃烧干燥过程的传热特性,我们建立了一台Helmholtz型脉动燃烧器,所用燃料为液化气,采用水冷方式。通过脉动气流与黄铜球之间的对流传热实验,应用集总热容法确定了在不同频率脉动气流中黄铜与气流间的对流传热系数,探究了脉动频率对脉动燃烧干燥过程气流与物料间对流传热系数的影响,并建立了相应的准数关联式。应用建立的关联式,对耐火土颗粒在脉动燃烧气流中的干燥过程进行了预测,并与实验值作了比较,结果表明预测值与实验值吻合较好。Although pulse combustion devices exhibit a high thermal efficiency and low pollutant emission when used in a drying process, a broad application of these dryers has been limited because of a lack of understanding of the fundamental controlling heat and mass transfer. This paper reports the results of an experimental investigation of heat transfer between unsteady airflow and a brass sphere under various oscillating frequencies. In order to generate an unsteady flow, we constructed a gas-fired, water-cooled pulse burner. The burner is ofa Helmholtz type and its operating frequency can be adjusted by changing the tailpipe length. The heat transfer coefficient between unsteady air outflow and brass was determined by the lumped capacity method. The effect of airflow oscillating frequency on heat transfer coefficient was investigated and their correlation was established. Refractory clay particles in the oscillating airflow were dried and the effect of the frequency on the drying process was predicted using the heat transfer coefficients obtained.

关 键 词：脉动燃烧 干燥 传热 耐火土 脉动频率 

分 类 号：TQ052.73[化学工程]