Ultrasound-Assisted Regeneration of Zeolite / Water Adsorption Pair

The experimental setup for the ultrasound-assisted regeneration of zeolite 13X consisted of a desorption bed, an ultrasonic transducer, a function generator, a high frequency-low slew rate amplifier, a cartridge heater, and a power supply. The bed was of hollow cylindrical shape machined out of aluminum 6061 rod, and the ultrasonic transducers used were of low-heat piezoceramic type. The desorption bed was attached to the transducer with resin epoxy, and drying of the zeolite sample was achieved by heating it in an oven at 280 °C. The ultrasonic power was regulated using a shunt resistor, an oscilloscope, and voltage probes. The ultrasonic power was determined as the product of the root mean square value of voltage across the transducer and the root mean square value of alternating current passing through the transducer, multiplied by the cosine of the phase angle between the voltage and current. The regeneration temperature was measured at three different locations using OMEGA T type thermocouples and a NATIONAL INSTRUMENTS data acquisition device. The experimental results showed that using ultrasound enhances the regeneration of Zeolite 13X at all the aforementioned power ratios and frequencies. With regard to ultrasonic power, the highest energy-saving power ratio was observed at 0.25 and with an increase in ultrasonic power, the effectiveness of applying ultrasound decreased drastically. In terms of ultrasonic frequency, lower frequencies resulted in higher efficiency and energy savings, and it was concluded that the effect of ultrasonic radiation becomes more significant at lower ultrasonic frequencies. The zeolite 13X beads used in this study were procured from SORBENT SYSTEMS IMPAK Inc. The physical properties and specifications provided by the supplier are presented in Table 1. The resonant frequency of the transducers was determined using an oscilloscope and a shunt resistor, and the resonant frequencies of the unloaded transducers provided by the supplier were validated. The resonant frequency of the transducer-bed assembly was measured to be 24.3, 31.5, and 75.5 kHz, respectively. The experimental ultrasonic-thermal power combinations are presented in Table 2. Thermal power was regulated through a power supply connected to the cartridge heater, and the ultrasonic power was regulated using a shunt resistor, an oscilloscope, and voltage probes. The ultrasonic power was determined as the product of the root mean square value of voltage across the transducer and the root mean square value of alternating current passing through the transducer, multiplied by the cosine of the phase angle between the voltage and current.