Heat transfer and pressure drop in ice-water slurries

Heat transfer and pressure drop were experimentally investigated for ice-water slurries flowing turbulently in a 24.0 mm internal diameter, 4.596 m long, horizontal, stainless steel tube. The slurry velocity of the experiments was varied from 2.8 to 5.0 m/s which encompassed the range of applicability to ice-water slurry-based district cooling systems, The previously reported phenomenon of flow relaminarization in ice-water slurries was observed in the current experiments. A reduction in frictional pressure drop associated with the flow relaminarization was measured as the ice fraction increased. An ice fraction of 4% marked a division in the rate of reduction, and a pressure-drop correlation equation was developed for ice fractions above 4%. Heat transfer coefficients were determined over the velocity range of the experiments. Consistent with the flow relaminarization, the heat transfer coefficient decreased with increasing ice fraction. A correlation equation was also developed for heat transfer coefficients at ice fractions above 4%. (C) 2000 Elsevier Science Ltd. All rights reserved.