Effect of applying ultrasonic on the regeneration of silica gel under different air conditions

To decrease the regeneration temperature of silica gel (an excellent desiccant), the non-heating regeneration method with ultrasonic has been proposed and studied in our previous papers in which the effect of acoustic parameters as well as drying air temperature on the regeneration process was investigated experimentally by desiccant-weighing method. In this paper, the effect of drying air temperature and humidity on the ultrasonic-assisted regeneration and the following adsorption features of silica gel will be further studied by measuring the states of drying air. Different inlet air conditions, i.e., 40, 50, 60 and 70 °C in temperature combined with 0.01, 0.015 and 0.02 kg/(kg dry air) in humidity, are designed for the experimental study. The mass of dry silica gel sample used in this study is measured as 175 ± 0.1 g, and the acoustic frequency and power of ultrasound are 23 kHz and 60 W, respectively. The two indexes, AERR (Average Enhancement Ratio of Regeneration) and AERA (Average Enhancement Ratio of Adsorption), are used to estimate the effect of ultrasonic on the regeneration and the following adsorption of silica gel. The experimental results show that the effect of ultrasound on the regeneration will first rise and then decline when the drying air temperature rises from 40 °C to 70 °C, while it decreases with the drying air humidity increasing from 0.01 to 0.02 kg/(kg dry air). Similar regular patterns can be found for the effect of regeneration assisted by ultrasonic on the adsorption of silica gel. Meanwhile, a theoretical model is developed to predict the regeneration rate of silica gel assisted by ultrasound and validated by experiments.

► We investigate the influence of ultrasound on regeneration and adsorption process.
► Regular patterns of influences of ultrasonic effect on the regeneration have been studied.
► The theoretic model is developed to for describing the silica gel regeneration assisted by ultrasound.
► The theoretic model has been validated by experiments.