Ice Slurry as Secondary Fluid in Refrigeration Systems : Fundamentals and Applications in Supermarkets

Abstract: This thesis summarises the work performed within the project known as ICE-COOL at the Royal Institute of Technology (KTH) on low tem-perature applications of ice slurry. The ICE-COOL project is a Euro-pean Community funded project within the 5th Framework Program. The task given to KTH was to find and characterize the best possible aqueous solution with a freezing point of -25 °C applicable for ice slurry with an operating temperature of -35 °C. The circumstances differ for low temperature ice slurry from medium temperature as a result of for example the change in thermo-physical properties due to increased addi-tive concentration and the lower temperature.Ice slurry is a mixture of fine ice crystals, water and freezing point de-pressant additives. The typical ice crystal size ranges between 0.1 to 1 mm in diameter. The main purpose of using ice slurries is to take advan-tage of the latent heat. More than a few requirements are to be fulfilled by an ideal ice slurry fluid. It should have good thermo-physical proper-ties, high heat transport and transfer abilities, as well as low pressure drop to facilitate small pumping power. The ice content of ice slurry af-fects all the mentioned abilities. Apart from the mentioned factors of the fluid, there are other aspects that have to be taken into consideration such as environmental pollution and toxicity, flammability, material compatibility, corrosion, handling security and cost.This thesis reports on the experiences accomplished and the initial ex-periments performed on low temperature ice slurry. The thesis also gives the background and fundamentals necessary for a discussion and com-parison of different aqueous fluids suitable for ice slurry in general and for low temperature in particular. In addition to the low temperature ap-plication, the thesis also reports on an initial energy consumption com-parison between using ice slurry and single-phase fluid in supermarkets by means of the simulation program CyberMart developed by Jaime Arias at the Department of Energy Technology at KTH.