Numerical Simulation And Optimization Of Ventilation Mode In Main Power House For Conventional Island

At present, China's social and economic sustainable development confronted urgent problems in energy consumption and environment pollution. On the premise of meeting the present economic development and people's living standard, how to reduce energy consumption, resource consumption and all kinds of pollutants become the most important challenges. As nuclear power in China's energy development strategy of status is rising, the number of nuclear power plants in China and capacity are increasing rapidly. So far, the ventilation mode mainly used in the main power house of the conventional island in a nuclear power station are air inlet with evaporative cooling (heating) unit and exhaust with roof mechanical fan. On the one hand, this scheme can effective control indoor air quality of the main building, ensure the safety operation of the generator unit; on the other hand, it can lead to an exorbitant initial investment and operation cost. However, reasonable natural ventilation can save energy and create the safe operation environment, which have a very significant meaning for the energy conservation and emission reductions, especially for the energy saving design of the industrial architecture.Because of the lack of design and operation experience, the main power house design regulations have not been compiled yet. In spite of structures of the main power house are very similar with the power of the turbine room, but they have many differences in equipment characteristics and heat pipe system. Therefore, the design of coal-fired power plants and related design manual cannot be used to ventilation system design of the main power house. In order to make the ventilation plan of the main power house energy-saving and afford guidance for projects of the same kind, with the design institute entrustment, the feasibility of ventilation modes for the main power house have been researched, and reasonable plan has been presented.First of all, by CFD technology, the wind environment has been stimulated around the main power house. Using the function of UDF to define the near-surface atmospheric wind profile function, which is closer to local landscape environment, and the velocity inlet conditions are imported through CFD interfaces into Fluent software. Pressure distribution has been simulated around the main plant and its surface. Then, the air distribution in the main power house has been simulated in typical operating condition by Reynolds averaged Navier-Stokes equation (RANS) approach, which involves Realizableκ-εmodel and Discrete Ordinates (DO) model, and the results include the ventilation volume, velocity and temperature of the main power house. Based on results above, the indoor air distribution is obtained through analyzing the ventilation volume of the main power house, the averaged-area temperature and exhaust temperature. By comparison tests, the factors (such as, wind speed and direction, air turbulence,outdoor air speed, air temperature, the size and number of fan and structural parameters like the size and position of ventilation openings, etc.) influencing the ventilation effect of the main power house have been discussed. The efficient measures to improve the indoor air distribution have been also proposed. Finally, to validate the accuracy of simulation method, the results between numerical simulation and experimental tests are compared. It suggests that a numerical prediction of indoor thermal environment in main power house for conventional island is feasible.The results show:wind and thermal buoyancy impact on the natural ventilation efficiency significantly, the main power house select the mode of natural inlet and mechanical exhaust ventilation or multi ventilation, the staff's thermal comfort and producing process requirements are satisfied. And both the area-averaged air temperatures in every layer and exhaust temperature can meet the standards.This thesis research fill the technology gaps in this field, it not only can guide similar projects' ventilation solutions, but also provide an important frame in preparing relevant design standards in the future.