Convective heat transfer coefficients (hfp) between fluids and cubic particles in continuous flow were investigated with respect to flow rate, viscosity, particle size, and radial location using noninvasive methods: (1) liquid crystal color change, and (2) measurements of relative velocity via flow visualization (for verification of liquid crystal results). All tests were conducted using sodium carboxymethyl cellulose (CMC) as the carrier fluid. Results indicate that hfp increases with decreasing particle size, increasing flow rates and (as expected) decreasing viscosity. Radial location affects hfp values: changing the particle position from the center to the bottom of the tube increases the convective heat transfer coefficient. Comparison between the methods indicates good agreement, providing a means of verification for the liquid crystal method.

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The convective heat transfer coefficient, hfp, between fluid and cubic particles was investigated with respect to flow rate, viscosity, and particle to tube dimension ratio using a moving thermocouple method. This study was conducted for a single particle. the determined values of hfp ranged from 199 W/m2C and 749 W/m2C. Results indicate that an increase in viscosity or dimension ratio decreased hfp values. In contrast, an increase in flow rate increased values of hfp. the effect of particle to tube dimension ratio was the opposite of those in previous studies by this method and appears to be due to differences inflow regime (laminar in this study, as compared to fully developed turbulence in previous work). A dimensionless correlation developed to relate Nusselt number to generalized Reynolds and Prandtl numbers, ratio of particle characteristic length and diameter of the tube, had an r2 value of 0.94.

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