A Study Of Electronic Anti-Fouling Technology To Enhance Heat Transfer

Fouling is a difficult problem in the industry all the time, because it reduces effective capacity, decreases productivity, consumes the fuel and accordingly results in tremendous economic loss. It is investigated that the economic loss that fouling of cooling tower of power houses causes every year in the Unite States is one million dollar and the direct loss which work reject caused by scale every year in China induces is more ten hundred million. Furthermore, fouling even endangers the safety of people and machine. So it is very important to study descaling. However, the existing chemical cleanout not only causes pollution, but also reduces the nature life of equipments. Electronic anti-fouling technology does not bring these problems, so researchers give it more attention.This paper performs the thermal experiment about electronic anti-fouling. The primary work is as following.1 > A heat transfer test section is designed and established on the basis of the existing experimental device of Electronic Anti-fouling .2> Some preparative experiments which include thermal balance experiments and forced convection heat transfer tests in the circular tube are done in order to validate the feasibility of the experimental system.3 ? We did the experiments and academic analysises from the point of view of fouling resistance and heat transfer coefficient by changing the coefficients such as the frequency of magnetic field, hardness of experimental liquid and so on. The experimental results are as follows:(1) Without EAF the fouling resistance increase along with addition of timeand change of the heat transfer coefficient is just contrary to the result. However, with EAF fouling resistance still enhances at the beginning of experiment and later, it gradually minishes after experiment has started for some time. Of course, the change of heat transfer coefficient still is contrary to the outcome. But when experiment lasts longer time, fouling resistance and heat transfer coefficient change in the same trend as the fore results at the beginning of the experiment. However, They all go to the tranquilization until the last.(2) Under the same experimental condition as ever but changing the frequency of magnetic field, we discover that descaling is the best when the frequency of magnetic field is 700 Hz.(3) Under the same experimental condition as ever but changing hardness of experimental liquid, we discover that fouling resistance reduces along with the increase of hardness of experimental liquid.4 According to the observation of scale specimen under a scanning electron microscope, we discover that the mechanism of electromagnetic anti-fouling is to change the shape of fouling crystal. In other words, harder and denser aragonite is changed into incompact calcite under the action of magnetic field. The conclusion is consistent with the past experimental results.