# Model Experimental Study on De-Icing Method of Bridge Pylon Beam Based on Electric Heating
## 4 Results and Analysis of De-Icing Tests  
### Anti-icing Tests  
#### 4.1.1 Critical Anti-Icing Temperature  
The critical anti-icing temperature is the critical temperature at which a component will be ice-free. The critical anti-icing temperature is different under different environments, and finding the critical anti-icing temperature can help to obtain the suitable pre-heating time. The specific method is as follows: when the temperature of the specimen reaches the same as the ambient temperature, turn on the heating and spray system at the same time, and the surface of the heating system will freeze first and then melt; record the temperature at the melting time as the critical anti-icing temperature of each group; repeat the test several times; and finally, take the average value as the critical anti-icing temperature. Five sets of anti-icing tests were carried out to obtain the critical anti-icing temperature. All the tests were carried out at \(-\)15 \({}^{\circ}\)C in a windless environment, with precipitation of 1 mm/min, a rainfall time of 120 min, and a pre-heating time of 0 min (the heating and spray systems were started up at the same time). Figure 12a shows the icing and melting process of the heating system surface under a no pre-heating condition. The time when the heating and the spray system were turned on was recorded as time 0. At the time of 3 min, the heating system surface started to freeze  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Test Conditions** & \(\mathbf{L_{max}/(\text{cm})}\) & \(\mathbf{L_{ave}/(\text{cm})}\) & **SE of \(\mathbf{L_{ave}}\)** & \(\mathbf{D_{max}/(\text{mm})}\) & \(\mathbf{D_{ave}/(\text{mm})}\) & **SE of \(  
due to the insufficient heat generated by the CFHC. A few small icicles could be seen on the bottom edge, and the number of icicles continued to increase. At the time of 10 min, the icing reached saturation due to the increased temperature. At the time of 11 min, the icicle on the left part melted and fell off. This means that the ice may begin to melt at close to 10 min and is in a state of saturation to be melted. The ice was all melted at the time of 19 min. Similar phenomena were shown in the five groups of experiments, and the temperature rise law of the heating system surface was also relatively close, as shown in Figure 12b. It can be seen in Figure 12b that the temperature of the heating system surface increases first and then tends to be stable after heating with electricity. During the heating process,  
Figure 12: (**a**) Test process during the no pre-heating anti-icing test; (**b**) temperature rise rules of the heating system with or without rainfall: A, B, and C represent the three thermocouples and \(-15\)\({}^{\circ}\)C is the ambient temperature. the temperatures of the three thermocouples were close, indicating that the horizontal temperature distribution on the surface of the heating module was uniform; so, thermocouple B was chosen to represent the temperature change on the surface of the heating system in the subsequent experiments. Under rainfall conditions, since the raindrops take away a certain amount of heat, the final stable temperature will be greatly reduced, with a temperature difference of about 14 \({}^{\circ}\)C. At the time of 10 min, the temperature rise rule of all five groups of tests showed a cooling trend. The reason for this may be due to the change in the ice accumulation pattern on the heating system surface. In the first ten minutes of rainfall, some raindrops stay on the surface of the heating system. Due to the temperature difference, the heat of the raindrops is taken away by the surface of the heating system and the air, thereby forming ice. At the same time, due to the interaction, the surface temperature of the heating system will increase accordingly because the temperature of the surface of the heating system at this time is much lower than the temperature of the raindrops.