In autumn, water flows in a closed underground channel. Every 100 meters, there is a vent pipe 0.01 m in diameter and 0.20 m high that opens to the atmosphere at 25°C. For a 1000 m long channel, there are 10 such vents. Calculate the evaporation rate of water in kg/day based on mass transfer from the surface of the water. Assume vapor pressure of water at 25°C is 76 mmHg. At 25°C, DAB=0.26×10^?4 m2/s ; at 0°C, DAB=0.22×10^?4 m2/s