Numerical Simulation And Analysis On Flow Field Of Air-cooled Unit With Different Ventilation

The numerical simulation and analysis of conventional air-cooled unit and a new air-cooled one in which the incoming air is swirled by adding a swirler between the outlet of fan and cooling finned tubes have been made by employing actual data of Longshan power plant based on FLUENT software on the basis of presenting the developing history of air-cooled technology and the research status of air-cooled ventilation and swirling technology at home and abroad. The blade in the swirler can be divided into the four types:straight vane, folded vane, like-wing vane and barrel type vane with trumpet outer. The flow fields related to three different attack angles of vane which are chosen to represent the weak swirl intensity, the stronger swirl intensity and the strongest swirl intensity are simulated for each type of swirler in air-cooled unit. The optimal angles of vane are found by exploiting the result of simulation, which represent the best swirl intensity for each type of swirler; accordingly, the minimal heat transfer coefficient is achieved in which the heat transfer capability of air-cooled unit is not fully exerted. As increase of head load or/and decrease of heat transfer area can raise the economy in power plant, optimums of heat load and heat transfer area are analyzed under different types of swirler with different angle of vane by numerical simulation and heat transfer calculation and hence the relevant heat transfer capability can be fully expressed without changing other condition. It is found that the maximal deviation of heat transfer coefficient is less than1%by comparing heat transfer coefficient calculated after optimizing with one calculated under the traditional ventilation. Hence, the optimum heat load and heat transfer area obtained in the paper can be utilized for engineering calculation.