Carbon fiber is a new type of high-performance fiber reinforced material, which has many excellent properties such as high strength, high modulus, high temperature resistance, wear resistance, fatigue resistance, corrosion resistance, creep resistance, electrical conductivity and thermal conductivity. It can reduce the weight of components, thereby improving the technical performance of components. Therefore, using carbon fiber as an electric heater has many excellent properties that are incomparable to metal, PTC and other electric heaters:
Rapid temperature rise
Far infrared ray that can produce life light needed by human body 8 μ m－15 μ m。
High electric heating conversion efficiency and energy saving
Carbon fiber electric heater is a kind of all black body material. Its electric heating conversion efficiency is 30% higher than that of metal heating, and its electric heating efficiency is about 100%.
High tensile strength
Under the same allowable current load area, the strength of carbon fiber is 6-10 times higher than that of metal wire, and it will not break during use. Therefore, the tensile strength does not change during electric heating.
No arcing due to disconnection
Effectively put an end to fire.
Light weight
The weight of the component is effectively reduced, thereby improving the technical performance of the component.
Stable chemical performance
It is resistant to corrosion and oxidation. When heated to 3000 ℃ in the absence of oxygen, its mechanical properties do not change at all. In the electric heating state, it overcomes the shortcomings of low strength of metal wire, PTC, and silicon carbide electric heater, which are easy to be oxidized and burnt out.
Long service life
The carbon fiber heat generator has the same life as the building.
The pavement condition is an important factor affecting road traffic. In winter, when the cement concrete pavement is covered with snow and freezes due to snowfall, it has a serious impact on driving safety and people's life, even causing huge economic losses. At present, all countries in the world widely use the method of spraying salt (NaCl, CaCl_2) to melt snow and ice, which seriously affects the durability of road pavement concrete, causes damage to pavement facilities, and destroys the surrounding ecological environment. Therefore, it is of great practical significance to seek a new method of snow and ice melting.
In this artical the carbon fiber heating wire is laid in the concrete pavement as an electric heating material. With the research background of snow melting and ice melting in winter, the feasibility of snow melting and ice melting of the carbon fiber heating wire concrete is mainly studied. At the same time, the factors affecting the effect of snow melting and ice melting are tested and analyzed by using the knowledge of heat transfer, The research provides a theoretical basis and reference value for the engineering application of carbon fiber heating wire for snow melting and deicing on concrete pavement. The main work is as follows:
(1) According to the law of conservation of energy, the differential equations of electric heating and cooling of concrete with carbon fiber heater are established and solved, and the temperature change curve of concrete with carbon fiber heater with time in the heating and cooling stages is obtained. The curve comprehensively reflects the influence of concrete section size, heat dissipation surface area, electric heating power and convection radiation heat transfer coefficient on the temperature rise and fall process of concrete. The electric heating temperature rise and temperature drop curves of carbon fiber reinforced concrete are tested and arranged, and the test results are in good agreement with the theoretical calculation values.
(2) When the electric heating effect of carbon fiber heating wire is used for road snow melting and deicing, the convective radiation heat transfer loss is the main factor affecting the effect of road snow melting and deicing, while the wind level, ambient temperature, and whether there is thermal insulation layer have a great impact on the heat loss. By analyzing the relationship between the temperature rise of the concrete slab surface and the wind power level and the ambient temperature under different input power, the influence of the wind power level and the ambient temperature on the temperature rise effect of the slab surface is obtained; Through the experimental study on the temperature rise of small concrete slabs with and without thermal insulation layer, the difference of the temperature rise effect of the slab surface with and without thermal insulation layer is obtained.
(3) A test device for snow melting and ice melting of concrete slab with carbon fiber heating wire is established to test the heating uniformity of concrete slab with carbon fiber heating wire. The research results show that when the spacing is 10 cm and the concrete with carbon fiber heating wire is powered on, the concrete slab surface can produce uniformly distributed heat to meet the needs of uniform melting of ice and snow. (
4) The experiment of melting ice and snow on the small concrete slab of carbon fiber heating wire is carried out indoors (freezer), and the influence of input power, ambient temperature and the thickness of ice and snow layer on the melting time is obtained. On this basis, the application experiment of melting snow and ice on the large concrete slab in the field is carried out. The research results show that when the paving power is 500 W/m~2~1000 W/m~2, the heat generated by the carbon fiber hot wire concrete slab after being electrified can effectively remove the ice and snow on the road surface and meet the needs of snow melting and ice melting in winter.
(5) The finite element analysis of the temperature field of the snowmelt and deicing of the concrete slab of the heating line uses the frozen pavement as the research object. The important parameters in finite element analysis of temperature field are determined by trial and error method according to the temperature monitoring results of temperature rise test
