The applications in gas–solid systems are less common, because,as mentioned before, the high impedance mismatch and the high ultrasonic energy attenuation in air makes the transmission of ultrasound from the transducer to the air and from the air to the solid difficult (Garcia-Perez et al., 2009). Nevertheless,some applications have been developed in the convective drying field to overcome these challenges. This is the case of the stepped plate ultrasonic transducers developed by Gallego-Juárez et al.(1999). These prototypes have been used in the convective drying of several food products, applying airborne ultrasound or with direct
contact between the transducer and the solid (de la Fuenteet al., 2006; Gallego-Juárez et al., 2007). Another alternative consists of the development of vibrating drying chambers to apply air borne ultrasonic energy (García-Pérez et al., 2006a). The promising results of this system will be addressed in the following sections.
The applications in gas–solid systems are less common, because,as mentioned before, the high impedance mismatch and the high ultrasonic energy attenuation in air makes the transmission of ultrasound from the transducer to the air and from the air to the solid difficult (Garcia-Perez et al., 2009). Nevertheless,some applications have been developed in the convective drying field to overcome these challenges. This is the case of the stepped plate ultrasonic transducers developed by Gallego-Juárez et al.(1999). These prototypes have been used in the convective drying of several food products, applying airborne ultrasound or with directcontact between the transducer and the solid (de la Fuenteet al., 2006; Gallego-Juárez et al., 2007). Another alternative consists of the development of vibrating drying chambers to apply air borne ultrasonic energy (García-Pérez et al., 2006a). The promising results of this system will be addressed in the following sections.
การแปล กรุณารอสักครู่..