Simulation on water temperature change process of diversion channel for pumping well water to melt ice at high altitude and cold regions

Abstract: In the northwest alpine regions, pumping well water to melt ice (PWWMI) is an effective method to solve the ice problem for diversion power station in winter. In this study, the diversion channel of Hongshanzui Water Power Station in Manas River of Xinjiang was selected as the study area (86°03′15″E and 44°05′01″N) and a field survey was conducted in February 2013 to analyze the change process of water temperature. The prototype observation results yielded a series of indicators, including the temperature and discharge of well water, and the temperatures of channel water before and after well. Based on the diversion channel of Hongshanzui Water Power Station, a three-dimensional turbulence numerical model was proposed to simulate the change process of water temperature of diversion channel for PWWMI. The discharge and temperature of 5# well water was taken as the initial boundary, different values of water temperature distance from 5# well were predicted. The change process of water temperature obtained from prototype observation experiment was compared with the simulation results, and the results indicate that the simulation results were in a good agreement with the experimental results, which can ensure the reliability of the simulation results. Thus, the changes of water temperature were simulated under different discharge and temperature conditions, including different discharges of well and channel water, different temperatures of well and channel water, and the changes of temperature and discharge simultaneously. The results showed that the changes of discharge and temperature of well water, and temperature of channel water were proportional to mixed water temperature, and the temperatures of mixed water increased with the increases of discharge of well water and temperatures of well and channel water, respectively. When the discharges of well water were increased by 1.2 and 1.4 times, decreased by 0.6 and 0.8 times compared with the original value of 0.16 m3/s, the temperatures of mixed water increased by 14% and 27%, and decreased by 27% and 14%, respectively. At the same time, when the temperatures of well water were increased by 1.0 and 2.0 ℃ compared with the original value of 10.00 ℃, the temperatures of mixed water increased by 9% and 18%, respectively. When the temperatures of well water were decreased by 2.0 and 1.0 ℃ compared with the original value of 10.00 ℃, the temperatures of mixed water was decreased by 18% and 9%, respectively. The variation of mixed water temperature with channel water temperature decrease by 0.1 ℃ was the same to that with channel water temperature increase by 0.1 ℃. However, the simulated results also showed that the discharge of channel was inversely proportional to mixed water temperature. The temperature of mixed water was decreased with the increase of discharge of channel water. When the discharges of channel water were decreased by 0.5 and 0.75 times, increased by 1.5 and 2.0 times compared with the original value of 10.00 m3/s, the temperatures of mixed water are increased by 67% and 22%, decreased by 29% and 33%, respectively. If the temperature of channel water was decreased to 0.25 times and the discharge of well water was increased to 4 times compared with the original values of 0.18 ℃ and 0.16 m3/s, the temperature of mixed water was increased from 0.14 to 1.43 ℃, which indicates that increasing the discharge of well water is the most effective ice-melting method. This study could provide valuable information for preventing ice hazards of diversion channel in the cold regions.