Piezoelectric atomizer in aeroponic systems: A study of some fluid properties and optimization of operational parameters

Abstract

The piezoelectric method to atomize fluids in aeroponic systems is known as a new application. In the current study, the effects of four independent variables on the misting rate were investigated. These variables were Dosage of Chemical Fertilizer (DCF), the Height of Solution above Piezoelectric Ceramic (HSPC), Piezoelectric Location at the Bottom of the Container (PLBC), and the Container Geometry (CG). Physical properties such as fluid density, viscosity, surface tension, Total Dissolved Solids (TDS), and Electrical Conductivity (EC) of the solutions were measured. Moreover, optimization was performed to determine suitable ranges of independent variables to get the optimum value of the misting rate. Results showed that the HSPC, PLBC, and CG significantly affect the total misting rate (P < 1%). Besides, the DCF, HSPC, and CG have significant effects on surface evaporation at a probability level of 1%. At the temperature of 25 ℃ and for different concentrations of fertilizer, the density, viscosity, surface tension, TDS, and EC varied between 1 002–1 006.5 kg/m3, 1.009–1.395 mPa·s, 0.071 82–0.072 98 N/m, 253–3 397 mg/L, 502–6 795 µS/cm, respectively. Total misting rate ranged between 0.499 and 5.720 g/min. In the outlet of the mist generation container, mass flow rate was in the range of 59.895 to 65.116 g/min. Also, theoretically calculated mist average droplet size was in the range of 2.90 to 2.92 µm for different fertilizer doses. The present study is the first research on the factors affecting the ultrasonic mist production rate in an aeroponic system. For future developments, effect of voltage, frequency, and using horn should be investigated. Besides, similar research should be done in the field of gas-phase bioreactors (mist bioreactors).