Characteristics of dynamic ice-making via Al2O3-H2O nanofluid’s vacuum flash
【Abstract】Al2O3 nanoparticles were added into the water with xanthan to prepare the well-distributed Al2O3-H2O nanofluid with ultrasonic wave. Based on the theory of flash evaporation, the experimental apparatus of dynamic ice-making under vacuum was designed. In the same flash pressure (300 Pa), the vacuum flash experimental characteristics in different conditions, such as solid adsorption, nanofluid concentration, particle size and diaphragm metering pump flow, were investigated. The results show that the adsorption action has obvious effects on keeping the stability of the pressure and it is useful to capture the water vapor in the system. When the temperature of the cooling medium is lower than the initial temperature of the adsorbent, the adsorbent has better adsorption capacity, but the cooling temperature should not be too low. The larger concentration of the nanofluid and the smaller particle size are better for getting the high ice packing factor of ice slurry. For the same concentration of nanofluid, the ice packing factor of ice slurry can be gotten by reasonable control of the diaphragm metering pump flow. In 2% (mass) NaCl, the concentration of nanofluid in different particle sizes should not exceed 0.05% (mass).
【Keywords】 nanoparticles; ice-making; vacuum; adsorption; ice packing factor; phase change;
(Translated by WANG DW)
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