Performance Analysis And Design Of Mechanical Ventilation Air Cooling System

The conventional natural ventilation and air cooling system of the thermal power plant adopts ambient air as a cooling medium,and uses the air density difference generated by the tower height to provide suction force to cool the circulating water in the air-cooled radiator.As a result,the power parameters of random sets and so on are increased,and the tower height of naturally ventilated cooling towers increases accordingly.As a result,the design difficulty and project cost will all increase.Mechanical ventilation and cooling system uses high-power axial fans to provide forced suction force,which provides a new choice for cold junction design under high-power and high-parameter conditions.By adopting the heat exchanger model provided in the CFD numerical simulation software and considering the phenomenon that the circulating water stratifies in the radiator,numerical simulation of the mechanical ventilation and air cooling system is carried out to analyze the change of the thermal performance of the system under the influences of different ambient wind speeds.Under the condition that the wind direction is parallel to the long axis of the tower,the heat transfer performance of the windward grid group is most violently affected by the ambient wind,and the heat transfer performance of the radiator arranged on the windward side is superior to the heat exchange performance of the radiator arranged on the leeward side.With the increase of ambient wind speed,the total heat exchange of single-row tower of mechanical ventilation and cooling system is gradually reduced,and the air mass flow rate near the heat exchanger is gradually decreased.Single row arrangement of the number of groups in the 6 to 8 groups the best overall heat exchange performance.According to the change of the thermal performance of the mechanical ventilation and cooling system,the system operation mode and the optimization and improvement plan of the model are taken.In the operation mode,the scheme of redistribution of circulating water flow and the redistribution of axial fan power are adopted.Circulating water flow redistribution with different wind speed of the air mass flow as the main reference,the final optimization of the six groups of programs using environmental wind speed 8m/s mass flow rate as a benchmark,the uneven distribution of the grid between the program,the tower row overall heat transfer performance to enhance the best.The change of axial fan power has a higher degree of optimization of the windward grid group than the optimization of the wind turbine tail grid group.Changing the fan power at large ambient wind speed can increase the overall heat exchange capacity of the system.For the structural change of the model,a scheme of adding a deflector near the first windward radiator is adopted.The results show that the deflector affects the air flow field in the tower.The higher the ambient wind speed,the more obvious the optimization effect is.