Experimental Study Of Effects Of Ultrasound On The Process Of Defrosting On Tube Surface And Finned Tube Surface

Frost is widely exists on the surface of heat exchangers of air conditioning system and refrigeration storage system, which may seriously reduce the operation stability and efficiency. Therefore, it is urgent to find a way to improving the formation of frosting on the heat exchanger surface. This paper try to introduce the ultrasound to improve the frost suppression and defrosting problem and the effect of ultrasound on the growth of frost on curved and cold surface is systematic studied.The microscopic visualization study is performed to investigate the influence of ultrasound in defrosting on cold curved surface. In order to visual study the structure on aluminum-made test-pieces under combined action of electric heating and ultrasonic, ultrasound and test pieces are threaded connection to build the experimental device. The defrosting mechanism is also analyzed. In addition, the effect of curvature radius and ultrasonic power on the distribution of frost layer are visualized and the change rule of frost covering rate is analyzed and concluded by binarizing the experiment pictures. The results display that the frost layer falling off first appear at the center of the circular tube because ultrasonic energy in the center of test-pieces is maximum. Besides, the ultrasonic energy is decaying along the direction of ultrasonic transmission and the frost layer is the last to fall off which is far away from the center.In addition, the coverage of frost layer decreases with the increase of ultrasonic power. The smaller of the curvature radius, the better of the defrosting.Then, the influence of fin parameters such as the fin thickness, fin spacing and the fin height are studied. Under the same experiment circumstances, the frost thickness and defrosting efficiency are observed visually, and it is found that the defrosting effect is better when the fin thickness is smaller, and the effect of fin spacing and the fin height are not distinct.In summary, the current work systematically investigates the feasibility of ultrasound defrosting on the cold curved surface. The study of frost distribution in a constant low temperature environment is also completed and, the relationship of ultrasonic power and coverage of frost is studied. The corresponding research results provide a theoretical and technical support for the effective frost suppression and defrosting as well as the optimization design of defrosting system in low temperate field, which is an effective supplement and perfection for the existing frost suppression and defrosting methods.