|Title:||An experimental study for scale prevention in boiler by use of ultrasonic waves|
|Authors:||Heo, Pil Woo; Lee, Yang Lae; Lim, Eui Su; Koh, Kwang Sik|
|Affiliation:||AA(Korea Inst. of Machinery and Mater., Taejon), AB(Korea Inst. of Machinery and Mater., Taejon), AC(Korea Inst. of Machinery and Mater., Taejon), AD(Kyungpook Natl. Univ.)|
|Publication:||The Journal of the Acoustical Society of America, vol. 112, iss. no. 5, p. 2441-2441 (ASAJ Homepage)|
|NASA/STI Keywords:||CHEMICAL REACTIONS, HEAT TRANSFER, METAL IONS, SURFACE REACTIONS, THERMAL RESISTANCE, ULTRASONIC RADIATION|
|Comment:||NASA/STI Accession number: 20020082568|
In case of a boiler, scale is made on the surface of tube by the chemical reactions of Ca and Mg ions contained in the water and heat transfer rate is reduced because of the increment of heat resistance. Thus, it brings about the reduced energy transfer efficiency and also environmental pollution due to the use of chemicals for scale removing. In this paper, we have first investigated the effects of irradiated ultrasonic wave on water with impurities in a beaker. The experiments show that exposed water is less transparent and has finer particles as compared to unexposed water. This means that the ultrasound shakes water in the beaker and breaks out particles, and so broken fine particles are suspend in the state of less precipitation. Second, the laboratory experiment with an exposed sample in the similar condition to the boiler shows better scale prevention effects as compared to the unexposed one. And also 20 kHz ultrasound represents about 3 times better scale prevention effects than 40 kHz. Finally, scale prevention experiments in the real small boiler tell us exposed sample results in 3659% less scale formation than an unexposed one.