煤油加热器螺旋管内煤油传热特性分析

Analysis of Heat Transfer Characteristics for Kerosene in Helical Tube of Kerosene Heater

关键词:  煤油加热器  超临界/裂解态煤油  传热计算 

Key words:  Kerosene heater  Supercritical/Cracked kerosene  Heat transfer calculation

摘要:

针对燃气加热方式的煤油加热器,为预测其工作性能参数发展了一维传热分析程序,试验验证最大误差为9.7%,结果较为准确。利用该程序研究了煤油加热器流动传热规律及多个因素对其工作特性的影响规律。研究结果表明,典型工况下,煤油从入口到出口温度升高,雷诺数由5.94×10⁴升高至2.39×10⁶,普朗特数由11.2降低至1.4,存在数量级变化,说明对流换热情况复杂；煤油速度逐渐增大,高温区停留时间短,仅为0.28s,结焦影响小；燃气温度、煤油流量和燃气流量是影响其加热能力的主要因素,其作用大小依次降低,而煤油压力和燃气压力对传热过程影响很小。该方法可以有效预测煤油加热器的工作能力。 

Abstract:

A program of one-dimensional heat transfer analysis was developed for the kerosene heater based on gas heating to estimate its operation parameters, and the calculation results have a maximum error of 9.7% by comparing with experimental results. Researches on the characteristics of flow and heat transfer of the kerosene heater, and the effects of several factors on the operation rules were studied using the program. Under the typical condition, the results indicate that from inlet to outlet Re and Pr have varied greatly with temperature increasing, Re from 5.94×10^4to 2.39×10^6and Pr from 11.2to 1.4, and this shows the convection is complex. The velocity of kerosene increases gradually and the settling time in high temperature range is short, only 0.28s, then coke deposition effect is small. The main factors that influence heating ability of kerosene heater are temperature gas, mass flow rate of kerosene and mass flow rate of gas, with the effect weakening gradually, and the pressure of kerosene and gas almost have nothing to do with the process of heat transfer. The program could indicate operation performance of the kerosene heater, and the results could offer reference for design of cooling configuration of ramjet. 