An experimental investigation was carried out to research the effects of ultrasonic waves on heat transfer, in subcooled boiling conditions, from a stainless steel horizontal cylinder, to distilled water. Actually the acoustical streaming influences the kinematic field and so increases the heat transfer coefficient. The aim of this paper is to find out the parameters that maximize the heat transfer coefficient. The authors had investigated the influence of the ultrasonic wave power, Pgen, the temperature difference between a prefixed water temperature and the water saturation temperature, ΔTSUB and the heat flux per unit surface, q”, dissipated on the cylinder by Joule effect. Each test is carried out at the frequency of 40 kHz and, at the moment, the cylinder is located in a fixed horizontal position. In this paper, after a description of the experimental apparatus and procedure, are shown the experimental results varying q” and Pgen with ΔTSUB=25 and 35°C. The data highlight that the maximum heat transfer coefficient occurs when the Pgen and the ΔTSUB are higher, the heat flux per unit surface, q”, being equal. Furthermore the ultrasonic cooling effect increases with the cylinder temperature increasing. This one result should be considered the starting point for a practical application of the ultrasonic waves in the last generation electronic components cooling.
Heat transfer enhancement from a circular cylinder to distilled water by ultrasonic waves in subcooled boiling conditions
BARTOLI, CARLO
2009-01-01
Abstract
An experimental investigation was carried out to research the effects of ultrasonic waves on heat transfer, in subcooled boiling conditions, from a stainless steel horizontal cylinder, to distilled water. Actually the acoustical streaming influences the kinematic field and so increases the heat transfer coefficient. The aim of this paper is to find out the parameters that maximize the heat transfer coefficient. The authors had investigated the influence of the ultrasonic wave power, Pgen, the temperature difference between a prefixed water temperature and the water saturation temperature, ΔTSUB and the heat flux per unit surface, q”, dissipated on the cylinder by Joule effect. Each test is carried out at the frequency of 40 kHz and, at the moment, the cylinder is located in a fixed horizontal position. In this paper, after a description of the experimental apparatus and procedure, are shown the experimental results varying q” and Pgen with ΔTSUB=25 and 35°C. The data highlight that the maximum heat transfer coefficient occurs when the Pgen and the ΔTSUB are higher, the heat flux per unit surface, q”, being equal. Furthermore the ultrasonic cooling effect increases with the cylinder temperature increasing. This one result should be considered the starting point for a practical application of the ultrasonic waves in the last generation electronic components cooling.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
