Turbulent pipe flow of an internally heat generating fluid

Experimental measurements, supported by analysis, were performed to determine the heat-transfer characteristics of an internally heat generating fluid in the fully turbulent regime. Heat was generated uniformly within the flow by electrical dissipation, the working fluid being an aqueous solution of sodium chloride salt. Measurements were made of the fully developed wall-to-bulk temperature differences for flow in an adiabatic pipe; data were also collected in the thermal entrance region. The Reynolds numbers and the Prandtl numbers, respectively, ranged from 10,000 to 80,000 and from 3 to 4. The small wall-to-bulk temperature differences (between 1 and 2 deg F) necessitated special care and instrumentation beyond that required in conventional turbulent heat-transfer measurements. The fully developed wall-to-bulk temperature differences were in very satisfactory agreement with the analytical calculations. The consistent scatter in the data was no more than ± 7 percent over the entire Reynolds number range. The analytical solutions were found to be very sensitive to the choice of the eddy diffusivity for heat. The assumption of equal diffusivities for heat and momentum led to the most satisfactory agreement between the experimental and analytical results. Additional numerical results are presented which include fluids with Prandtl numbers ranging from 1 to 100 for Reynolds numbers from 10,000 to 150,000.