Analysis On Thermo-flow Characteristics Of Air-cooled System Under Windly Conditions

The thermo-flow characteristics of the air-cooled system directly affect the heat transfer efficiency of the air condenser and further affect the back pressure and safety and economy of the steam turbine.Based on three dimensions with the computational fluid dynamics software,the Navier-Stokes equation and k-? turbulence equation for solving the flow field of the air-cooled system in,the flow heat transfer characteristics of the 600 MW direct air cooling system in the ambient wind field were studied.The main research contents are as follows:Firstly,the influence of ambient wind speed,ambient wind direction and ambient wind temperature on the air-cooled system was studied.The results show that:with the increase of the ambient wind speed,the air temperature of heat transfer at the inlet of the fan keeps increasing,and the volume flow rate continues to decrease,and the decline rate of heat transfer efficiency is accelerated.However:when the wind speed exceeds 6m/s,the decline rate of heat transfer efficiency slows down,and the reduction of air volume flow at the inlet of the fan is the main reason for the decrease of heat transfer efficiency.Different environmental wind cause air-cooled system affected by the environment wind area is different,but similar distribution,deterioration occurred in air-cooled platform windward area and around the edges,some of the wind turbine of a resistance due to the boiler,although can reduce fan inlet,in the hot air temperature,but also reduce the volume flow,intensifying environmental deterioration degree of wind,when the wind environment of 0°,flow heat transfer effect on air-cooled system is the most significant.With the increase of ambient temperature,the temperature difference of heat transfer between inlet and outlet air decreases,and the heat transfer efficiency decreases linearly.Secondly,the influence of three factors of ambient wind on the thermo-flow performance of the air-cooled system is numerically analyzed by means of orthogonal experimental design.The results show that the contribution rate of environmental wind direction to flow heat transfer performance is more than 45%,which is highly significant.Considering the interaction of each factor,the interaction between the three factors is not obvious.Finally,based on the quadratic regression orthogonal test method,the numerical calculation of the aerodynamic performance of the thermo-flow characteristics of the air-cooled system with different installation parameters of the Wind Guiding Nets is arranged,the optimal solution of the objective function is determined by the regression equation with obvious loss of fitting,and the installation parameters of the air-cooled system are optimized.The results show that when the number of diversion net is 4,the installation parameters of the optimal diversion net are:the opening rate is 45%,the Angle is 45°,the width is 2m and the spacing is 4m.After the optimized design of the Wind Guiding Nets,the inlet flow of the axial flow fan is obviously improved,the eddy current disappears,and the outlet flow field of the direct air condenser is uniform.The return rate of hot air decreased by about 3%on average,and the volume efficiency and heat transfer efficiency of the fan were improved,with an average increase of about 6%under the dominant wind direction.It can be seen that the thermo-flow of the optimized air-cooled system are significantly improved,through the research and analysis under different wind direction,and it can adapt to the wind field changes in different environments,which indicates that the optimal design of the installation of Wind Guiding Nets is feasible,and can provide reference value for the optimization design and transformation of direct air cooling system.