Research On The Convection Heat Transfer Of Air Across Wires In The Icing Environmental Conditions

With the changes of the environment and climate, the electrical transmission lines icing occurs frequently. Atmospheric ice accretion on conductors is becoming one of the major problems in planning and construcing power transmission lines and communications networks. China is one of the countries where ice accretion is very serious affected by climate and terrain. The electrical transmission lines icing causes great economic loss in china every year,it has becoming an urgent problem in power and communications industry.Firstly, the article reviewed the research status of conductor icing at home and abroad,introduced various anti-icing,de-icing technology features and methods and some existing problems about ice accretion. The main content of this article are proposed.Secondly, this article introduced the basic concept and mechanism of icing. ice accretion will be formed only at the right temperature(0℃～-10℃),humidity(above 85%)and wind velocity. Icing forms are not the same in different weather conditions, such as glaze,rime,wet snow and so on. The apparent characteristics and physical properties of icing are different.Thirdly,the collection coefficient is obtained through a number of experimental tests. The reaction of the collection coefficient is the ability that wires capture the supercooled droplets in the air. Through changing the air temperature, wind speed, droplet diameter and other meteorological parameters, we obtained the law of conductor icing collection coefficient under different meteorological conditions and influencing factors of the collection coefficient.Then, through analysis the heat balance equation of the heated wires and the different characteristics of the heat transfer process in the ice accretion process on overhead transmission wires, the theoretical formula of heat transfer coefficient is obtained. The convection heat transfer is calculated through experimental study in the icing environmental conditions. Ultimately, we obtained that the convective heat transfer coefficient increased with the increasing of wind speed and the current which pass through lines and the air temperature have a little effect.Finally, we obtained the low of local convective heat transfer coefficient through experimental study. The local convective heat transfer coefficient is decreased first and then increased with increasing angle. On this basis, verified the reliability of the experiment compared with the local convection heat transfer when air across rotating cylinder.The results of this article have very important meaning of the mechanism of anti-icing. This article was carried out a detailed experimental and theoretical study about the collection coefficient and the convection heat transfer. The experimental results can be used to provide theoretical support for anti-icing based on the Joule effect.