Experimental study on the preparation of binary ice by additives enhanced vacuum flash evaporation.

• Water vapor is trapped using a coupled adsorption chamber with a low temperature condensing coil. • Explore the effect of different additives (MgCl 2 , ethylene glycol, nano Fe 3 O 4) on the vacuum ice making process. • The added of additives is beneficial to the formation of ice slurry and the refinement of ice crystals. • Fe 3 O 4 nanofluid is beneficial to reduce ice making subcooling and improve ice slurry thermal conductivity. • Ethylene glycol is not suitable as an additive for vacuum flash ice making. Being a novel energy storage medium, ice slurry has the advantage of good fluidity, high latent heat and heat transfer efficiency, which has a broad application prospect. In this work, the ice making characteristics of different types of additives (MgCl 2 , ethylene glycol and magnetic iron oxide nanoparticles) in a binary ice system by vacuum flash evaporation under the action of solid adsorption were experimentally investigated. Subcooling, flash rate, ice packing factor, latent heat and thermal conductivity were measured to evaluate the performance of ice production. The results showed that 0.075% wt of iron oxide nanoparticles and 1% wt of MgCl 2 are more suitable to be used as additives for binary ice preparation than ethylene glycol, with the former outperforming the latter. Under optimal conditions, compared with pure water for ice making, the subcooling degree of iron oxide nanofluid was reduced by 55.80%, and the thermal conductivity and ice packing factor were increased by 98.80% and 54.22%, respectively. The subcooling degree of the MgCl 2 solution was reduced by 37.52% and the ice packing factor was improved by 59.51%. Meanwhile, DSC tests showed that the latent heat of the nanofluid was almost independent of the nanoparticle concentration. However, the increase of MgCl 2 solution would cause the decrease of latent heat. In addition, high concentrations of additives can inhibit ice crystal nucleation and growth, but a certain concentration of additives facilitates ice crystal refinement in vacuum ice making process, which is conducive to the transportation of ice slurry. [ABSTRACT FROM AUTHOR]