高温流化床水平埋管局部瞬态换热系数的测量

Measurement of Instantaneous Local Heat Transfer Coefficients between Immersed Horizontal Tube and Bed in a High Temperature Fluidized Bed

研究了一种测量高温流化床内水平埋管局部瞬态换热系数的热流计。其原理是在康铜基体上镀一层铜膜，从而形成一个铜－康铜表面薄膜热电偶，通过测定水平埋管表面的瞬时温度来计算出瞬态换热系数。研究结果表明，本热流计有着良好的动态特性。

A fast response heat flux gauge capable of measuring instantaneous local heat transfer coeHicients between a surface and a high temperature fluidized bed is developed. The gauge consists of a constantan cylinder of 9 mm in diameter and 10 mm in length. One end face of the cylinder is electroplated with a copper film to form a fast response copper-constantan sur-face thin-film thermocouple for the measurement of the instantaneous surface temperature of the gauge.An enamel-insulated copper wire is inserted in the constantan cylinder to a dis-tance of 4 mm from the other end, with one end of the wire in close contact with the cylinder so as to form a copper-constantan thermocouple for measuring the temperature of the cylin-der at a point of 6 mm from the film, With the two temperatures measured, as boundary conditons for solving the one-dimensional unsteady heat-conduction equation, the instanta-neous local heat transfer coefficients can be obtained. The response time of the gauge is less than 2.57 ms.Tests are performed in a fluidized bed of a cross section of 160×230 mm and at a temperature of 1034 ℃.