Numerical Simulation Of Heat And Mass Transfer In Tail Water Tunnel

Using tail water tunnel to cool or heat air may gain efficient energy saving of air-conditioning system of hydrapower station. Accurate computation of the heat and mass transfer in the tail water tunnel is the basis of determining the air conditioning and ventilation system. For the complexity of heat exchange concerning with air, the surrounding rock and tail water, there is not efficient computation method yet. So it is extremely essential to develop the practical computational method for application.In this paper, the quasi-steady quasi-three-dimensional heat and mass transfer model in the tail water tunnel was found on the principle of thermal balance by using finite cell to control volume. In the model the tail water is considered as a constant temperature object, and the air is considered as just changing along the tail-water tunnel. The tunnel is divided into several segments and the heat-conduct between the adjoining segments is neglect. The iteration method coupling in each segment is adopted to assure the balance of heat and mass among the air, the tail water and the surrounding rock.In the paper the change of the air temperature (or humidity) and the temperature of the surrounding rock are analyzed on the data which is gained by simulated for 10years when the outdoor air temperature (or humidity) in 1995 in Ya'an is taken as the sample year. From the data the paper makes someconclusions as below:1. The tail water tunnel is a kind of good cold (or heat) source for cooling air in summer and heating up air in winter.2. The phase of the exit air temperature wave is not consistent with the inlet air but the phase of the exit air humidity wave.3. The temperature of the surrounding terrane periodically steadily changes when the inlet air periodically steadily changes. The swing would be attenuated and the phase would be delayed.The simplified model that this paper put forward has reflected the basic law of heat and mass transfer in tail water tunnel, and the computing means has practical value in project.