关键词: 干燥, 传热, 测量, 间接加热, 列管回转干燥机

Abstract: This paper presented a simple and reliable device system for the measurement of heat transfer coefficient between the immersed tube’s surface and particles in an indirect heating tube rotary dryer，based on analysis of heat transfer process in a tube rotary dryer. A mathematical model to derive heat transfer coefficient from the measured parameters was developed based on the unsteady heat transfer performance. Periodical instantaneous heat transfer coefficient between tube’s surface and particles was observed as the tube rotating with the cylinder. Low heat transfer coefficient was observed at the high position when the tube was immersed in the particle phase. Analysis of error transfer showed that the accuracy of heat transfer coefficient was sensitive to the measurement accuracy of tube surface area，tube’s surface temperature increasing ratio，electric current，temperatures of tube surface and materials. Test results also demonstrated that under the common six operating conditions in this paper，the developed measuring approach yielded high accuracy of heat transfer coefficient with relative error less than 3.5%，and the total measurement error was mainly composed of the error of tube’s surface temperature increasing ratio.

Key words: drying, heat transfer, measurement, indirect heating, tube rotary dryer