Piezoelectric Horn Research Articles

Design and evaluation of a new ultrasonic horn for viscosity reduction of heavy oil

Based on the basic principle of the sandwich piezoelectric transducer, a high-power ultrasonic horn which can be used for viscosity reduction of heavy oil and pour point reduction of crude oil with high pour point was proposed and designed. The basic frequency of the horn is 16.8 kHz, and the input electrical power is 1 kw. It can work continuously on the industrial scale. First, the impedance characteristic was derived for the simplified model of the sandwich piezoelectric horn on the basis of equivalent network method. Second, its properties such as the resonance frequency, conductance, and transmitting voltage response were simulated by using of ANSYSsoftware in air, water, and silicone oil, respectively. According to the simulation, a prototype was made and measured by an impedance analyzer. Its basic frequency is in good agreement with the simulation calculation. The result shows that this high-power ultrasonic horn is expected to be applied on the industrial scale in viscosity reduction of heavy oil and ultrasonic sludge disintegration.

Enhanced Deposition, Acoustic Agglomeration, and Chladni Figures in Smoke Detectors

A full-scale house fire test was conducted to investigate the accuracy of two proposed methods for determining whether a smoke or carbon monoxide (CO) alarm sounded during a smoke exposure. One method involves examining the plastic case of the alarm's piezoelectric horn for locally enhanced soot deposition and agglomerated soot particles. The other method involves examining the metal disc of the piezoelectric horn for a Chladni figure. Pairs of detectors, each consisting of one detector with its battery properly inserted and the other with its battery disconnected, were placed throughout the house. Each of the properly charged detectors was monitored to determine if and when the detector sounded. It was found that the presence of locally enhanced deposition and soot agglomerates on the main central opening of the plastic horn enclosure of a smoke or CO detector was a strong indicator that the alarm sounded. It was also found that the use of Chladni figures on the piezoelectric discs as an indication of the smoke detector sounding was not an accurate predictor.

Effect of tool drop on the performance of a high-frequency piezoelectric wire-bonding transducer system

This work describes a method to determine a suitable tool drop for clamping the bonding tool in a high-frequency (130 kHz) piezoelectric horn transducer used for wire bonding. Effect of different tool drops on four critical parameters, namely, the resonant frequency, the electrical impedance, the phase angle, and the tool tip displacement amplitude, were studied with the transducer system being driven at normal bonding power. Strong interdependence was observed among these parameters. The results were interpreted from the system stability and other physical point of views. Appropriate ranges of tool drop were found. With the tool drop in these ranges, it can produce desirable characteristics for the wire bonding.

Piezoelectrically Assisted Ultrafiltration

Abstract We have demonstrated the feasibility of using piezoelectrically assisted ultrafiltration to reduce membrane fouling and enhance the flux through ultrafiltration membranes. A preliminary economic evaluation, accounting for the power consumption of the piezoelectric driver and the extent of permeate flow rate enhancement, has also shown that piezoelectrically assisted ultrafiltration is cost effective and economically competitive in comparison with traditional separation processes. Piezoelectric transducers, such as a piezoelectric lead zirconate titanate (PZT) disc or a piezoelectric horn, driven by moderate power, significantly enhance the permeate flux on fouled membranes, presumably because they promote local turbulence. Several experiments were conducted on polysulfone and regenerated cellulose UF membranes fouled during filtration of model feed solutions. Solutions of poly(ethylene glycol) and of high-molecular weight dextran were used as models. We found that we could significantly increase the permeate flux by periodically driving the piezoelectric transducer, horn or PZT disc, by application of moderate power over short periods of time, from 20 to 90 seconds. Enhancements as high as a factor of 8 were recorded within a few seconds, and enhanced permeate fluxes were maintained over a prolonged period (up to 3 hours). The prolonged flux enhancement makes it feasible to drive the piezoelectric transducer intermittently, thereby reducing the power consumption of the piezoelectric driver. As piezoelectric drivers of sonically assisted ultrafiltration, PZT disc transducers are preferred over the piezoelectric horn because of their small size and ease of adaptability to ultrafiltration test cells. The horn transmits sonic energy to the UF membrane through a titanium element driven by a separate piezoelectric transducer, but a piezoelectric ceramic disc transmits energy directly to the UF membrane. Moreover, because piezoelectric ceramic elements can be fabricated in several configurations, they are potentially feasible for piezoelectrically driven ultrafiltration spiral-wound membrane modules.