Experimental investigation of additives enhanced vacuum flash evaporation for binary ice generation

摘要

In this study, an experimental investigation was conducted into the characteristics of different varieties of additives (including CaCl2, ethanol, and TiO2 nanoparticles) in the vacuum ice-making system under adsorption condition. The concentration of CaCl2, ethanol, and TiO2 nanoparticles were treated as experimental variables, while the supercooling degree, ice packing factor (IPF), flashing rate, thermal conductivity, and latent heat were taken as evaluation parameters. According to the experimental results, 0.20 wt% TiO2 nanoparticles and 1 wt% CaCl2 are applicable as additive, the former is superior to the latter, and ethanol is not suitable for use as additive. Under the optimal conditions, compared with distilled water, the supercooling degree, IPF, and thermal conductivity of TiO2 nanofluids are improved by 77.92%, 40.61%, and 57.23%, respectively; for CaCl2 solution, the supercooling degree and IPF are improved by 9.96% and 84.67%, respectively. Furthermore, though the flashing rate increases with the addition of additives, the flashing driving force remains sufficient. The latent heat of nanofluids is barely affected by the addition of nanoparticles. As the CaCl2 concentration is on the rise, both the thermal conductivity and the latent heat of CaCl2 solution show a decreasing trend.