Analysis On Flow Characteristic Of Ice Slurry In Network

The cold storage technology is widely used in the field of air conditioning system, forice slurry as a storage medium, it has become the research focus by scholars from differentregions because of its smaller particles, good fluidity and high speed of ice melting. Theobjectives of the present study is to analyze the flow characteristics of ice slurry within thepipe network, the flow resistance as well as the critical speed during the safe transportationon the base of the existing scraped-surface ice slurry generator.The research work is focused on the following aspects:1）Analysis of ice slurry properties: By analyzing the properties of ice crystal and watersolution in the ice slurry, the formula of the density of ice slurry, thermal conductivity andspecific heat can be derived. A conclusion is drawn that the thermal properties of the iceslurry are influenced by the conditions of the ice crystal and the solution.2）The numerical simulation of ice slurry flow in the pipe: Contours which display thedistribution of the ice crystal in the pipe are derived by using the double-fluid Eulerianmodel in the fluent. These contours show that the particles in the horizontal pipe distributeregularly from the top to the bottom. The ice slurry at the same cross-section is foundstratified which is caused by the buoyancy and collisions between particles. Thestratification can be more obvious when the flow velocity become smaller and the pipediameter become larger. In addition, the simulation analysis also show the rule how thecritical speed changes when ice slurry flow in the tube and the pressure drop values changewith the parameters such as diameter of ice particle, the diameter of the pipe, the inlet rateof ice, additive concentration, etc.a）The maximum occupancy rate (ice particle fraction) of ice crystal on the top is0.501during the safe transportation in the pipe. With the increase of some parameters such asdiameter of the particles, the ice particle fraction, the sodium chloride concentration and thediameter of the pipe, the ice slurry’s critical speed increases.b）Results show that when the ice slurry flow in horizontal pipes, the pressure drop inperunit increases when the flow rate and ice content increase, however, the value decreaseswhen the diameter of the pipe and particles increase.When compared with Bingham theoretical model, the above pressure drop valuescomputed by numerical simulation has a mistake at the most15%, hence, the calculation inthe fluent is proved rightly.3) The experimental analysis of the characteristics when ice slurry flow in the tube: The experimental unit involves in three systems: Refrigerant circulation system, iceslurry making system and ice slurry flowing within tube system. Observing the flowingstate on different conditions through visual glass tube, it can be seen that the ice slurrymixes evenly at high speed. However, the ice slurry in pipe appears flocculent substanceswhen the ice slurry flow slowly since the decrease of the disturbance caused agglomerationof ice crystal. The analyses of the experimental data shows that the pressure drop of the iceslurry is stepping up at low sodium chloride concentration, while at high sodium chlorideconcentrations the value presents a parabolic rise. In the end, comparing the results aboutthe relations between pressure drop and the ice particles friction got from both theexperiment and simulation, it can be found that the change trend is almost agreement. Andthe experimental value is higher, the biggest difference is5%, occurring in the tube withdiameter of32mm. This difference is caused by that the sodium chloride concentrationdecreases during the experimental process with the decrease of the ice particle friction.4)Because the concentration of sodium chloride will decrease with the ice particlesmelting, according to the theoretical value of the concentration of sodium chloride between1%-5%values in the chlor-alkali manual, relationship between the density of the sodiumchloride and the concentration in the scope, and the caculation of the sodium chlorideconcentration in the different ice particle friction is getted.