气体射流冲击对流换热系数试验研究

杜志龙; 高振江; 张世湘

气体射流冲击对流换热系数试验研究

Research on convective heat transfer coefficient with air jet impinging

摘要

摘要: 在气体射流冲击试验装置上，冲击温度105～135℃，气流速度6.7～14.4m／s，相对湿度0～30%的范围内，进行了对流换热系数的研究，得到如下结论：物料表面温度T接近饱和温度T_s时，对流换热系数值出现转折，拐点前对流换热系数h为拐点后的3～12倍。在表面温度Ts时，可获得较大的对流换热系数，对流换热系数h随温度、气流速度和湿度的增大而增大，最大可达1403w／(m²·K)。在表面温度T>T_s时，对流换热系数值明显变小，且与0%相对湿度的对流换热系数值接近一致；在气流速度为恒定时，温度和湿度对对流换热系数影响不明显；在温度为恒定时，对流换热系数随气流速度的增加而增大，湿度变化对其影响不明显，对流换热系数h在120～136w／(m²·K)范围内。

Abstract: With the airflow temperature 105～135℃,airflow rate 6.7～14.4m/s and relative humidity 0～30%.Research on convective heat transfer coefficient h in the air imping ment oven, the result indicates that when the temperature T is close to the saturation temperatures of gas(T_s), convective heat transfer coefficient h have changed,h_TT>Ts; When the temperature T< T_s, convective heat transfer coefficient h becomes greater while the humidity or the airflow rate is greater. The greatest hcan get to 1403w/(m²K); When the temperature T>T_s, the value of hbecomes smaller than ever, agreed on the value at humidity 0%.With the variety of temperature & humidity, the changes of his not significant at the constant airflow rate. At the constant temperature, the value of h increased with increased airflow rate, and the changes of his no obvious with increased humidity. The value of h ranged from 120 to 136 w/(m²K).

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