Field test and heating power calculation of the electric heating technology to reduce icing for long-distance water canal operation

The canals can always shut down nearly for half year in cold regions, due to the freezing of water. It is a serious threat to the efficiency of canal water delivery and economic development. A key position can be found in the formation of ice cover, according to the canal water frozen and the development of ice cover. And the slope of the canal is one of these key positions. In this study, an electric heating technology was proposed to reduce the icing for the better extent of the canal operation time in winter. The skin effect heat cables (a heat cable with high heating efficiency, reduced circuit voltage, and single power supply for long-distance heating) were installed at the canal slope near the water surface along the canal. Three forms of heat transfer device were also designed for the application requirements. This electric heating technology was tested in the field at the ambient temperature of 0.7 to −23.5 ℃. The heating power was calculated for the canal's winter operation, and then compared with the electric heating in oil pipeline project. The field test results show that this electric heating technology was fully met the winter operation of the long-distance canal. The heat transfer device effectively extended the influence of the heat sources on the canal in winter. This electric heating technology effectively raises the surface water temperature compared to the no-heating situation. The canal water within 5 cm around the heating devices remained free from the freeze under the heating power of 120 W/m at the ambient temperature of −20 ℃, or under the heating power of 84 W/m at the ambient temperature of −15 ℃. Only the heating power of 56 W/m was needed to maintain the positive temperature of heating devices at an ambient temperature of −15 ℃, while the heating power of 30 W/m was needed to maintain a positive temperature of heating devices at the ambient temperature of −10 ℃. The heating power was calculated at different ambient temperatures of this electric heating technology, in order to reduce the icing for the long-distance water canal operation. The modified formula provided the theoretical basis for the electric circuit design. The running heating power demonstrated that the heating power of 226 W/m was selected for the canal operation at −39 ℃, which was the lowest temperature in this local area. The power consumption of this device was about 10.8 (kW·h)/(m·d). Only the heating power of 46 W/m was for the canal operation at −8 ℃, which was the average temperature of this local area. The power consumption of this device was about 2.2 (kW·h)/(m·d) at this moment. A smaller energy consumption which shows a high feasibility was achieved in this electric heating technology for the canal winter operation at the same ambient temperature, compared with the electric heating in the oil pipeline project. Therefore, this electric heating technology can be expected to reduce the icing for the long-distance water canal operation in winter. The finding can provide a high-value promotion in the canal of a hydropower station in winter.