A novel instrumented heat transfer tube for fluidization research. Topical report, January 1991--June 1992

Abstract

A novel heat transfer probe capable of measuring simultaneously the time varying heat transfer coefficient around the surface of a heat transfer tube and the time varying static pressure fluctuations in the vicinity of the tube surface was built and tested. The probe consisted of a 2`` OD -- 1 inch ID stainless steel tube with a surface mounted thermocouple and pressure taps above and below the thermocouple flush with the surface of the tube. Simultaneous surface temperature data and local static pressure fluctuations were measured at different fluidizing conditions in beds of fine, 250 micron, sand. Time varying heat transfer coefficients were obtained by solving the unsteady conduction equation in the wall of the tube using the surface temperature measurements as the time varying boundary condition. Heat transfer coefficients obtained by this technique were of similar magnitude to those measured in similar beds at similar conditions. The time varying static pressure fluctuations obtained from the two pressure taps mounted in the tube wall contained considerable noise which made comparison, using Fourier Transform Techniques, of the temperature and pressure data impossible. However, visual observations of the two sets of data suggest that a correlation may exist but would require the filtering or elimination of noise from the pressure transducer.