混凝土表面自然对流换热系数的实验研究

Experimental research on natural convective coefficient of concrete surface

提出了空气—混凝土表面在自然状态下对流换热系数的实验方案。采用混凝土空心圆管试件,从圆管内部加热,试件混凝土内部布置18个热电偶测点测读温度场。利用专门设计制作的实验装置,可全自动控制加热过程并自动记录实验数据。进行了5个混凝土试件实验,并设定不同的圆管内部加热温度进行了多次测读,结果具有很好的一致性。实验结果表明,空气—混凝土表面对流换热系数在自然状态下基本为一常数,不随表面温度的变化而改变。实验所得到的自然对流换热系数,可用于混凝土结构温度效应计算。

An experimental method to measure the natural convective coefficient of air - concrete interface is suggested. The concrete tube element was heated from inside of the tube. Eighteen thermocouples were arranged inside the concrete dement to measure the temperature distribution. The heating process was controlled and the test data were recorded automatically by a specially developed control system. Five concrete tube elements were tested for many times according to different inner heating temperature. The test results coincide very well. The experimental result shows that the natural convective coefficient of air-concrete interface is nearly constant. Convective coefficient doesn＇t change with the temperature of concrete surface. The experimental result of natural convective coefficient can be used in the analysis of thermal effect in concrete structure.