Rheology, flow behaviour and heat transfer of ice slurries: a review of the state of the art

This paper reviews recent studies on rheology, flow behaviour and heat transfer of two-phase aqueous secondary refrigerants (ice slurries). The difficulties in measuring their rheological properties for which standard rheometers prove to be poorly adapted are analysed. Special attention is paid to "vane-in-cup" rheometers, which can make it possible to determine the yield stress. Pressure losses in cylindrical tubes have been measured by many authors. Even if the results generally agree with two-phase flow theory, divergences in sensitivity to the solid fraction can be observed. The stratification observed by some authors for small-Reynolds-number flows and its effects on the pressure drop are addressed. In a last part, information concerning numerical values of the heat transfer coefficient of ice slurries are summarized. Heat transfer coefficients depend on many parameters, but are largely influenced by the flow regime. A geometry of heat exchanger is then proposed, which has already been effective for single-phase flows, and which may enhance heat transfer in ice slurry flows. (C) 2002 Elsevier Science Ltd and IIR. All rights reserved.