Experimental Investigation of Enhancement of Natural Convective Heat Transfer in Air Using Ultrasound

Abstract

One of the methods to improve convective heat exchange is the application of ultrasound assistance. However, little is known about ultrasound application in the air. The main purpose of this study is to investigate the effect of ultrasound on natural convection cooling. The tests are based on the cooling of the metal samples (in four different shapes) preheated to a temperature of 60 °C. Cooling takes place in free convection without and with the use of ultrasound at different powers (50 W, 100 W, 150 W, and 200 W). The study uses a mathematical model based on a small Biot’s number assumption. The values of the convective heat exchange coefficients are determined by using an approximation of the experimental results. The coefficients obtained are an increasing exponential function of the applied ultrasound power. This study indicates the possibility of using ultrasound to improve heat transfer by free convection.