Numerical simulation of the thermal-flow characteristics and heat transfer performance is made of an air-cooled steam condenser (ACSC) in a thermal power plant by considering the effects of ambient wind speed and direction, air-cooled platform height, location of the main factory building and terrain condition. A simplified physical model of the ACSC combined with the measured data as input parameters is used in the simulation. The wind speed effects on the heat transfer performance and the corresponding steam turbine back pressure for different heights of the air-cooled platform are obtained. It is found that the turbine back pressure (absolute pressure) increases with the increase of wind speed and the decrease of platform height. This is because wind can not only reduce the flowrate in the axial fans, especially at the periphery of the air-cooled platform, due to cross-flow effects, but also cause an air temperature increase at the fan inlet due to hot air recirculation, resulting in the deterioration of the heat transfer performance. The hot air recirculation is found to be the dominant factor because the main factory building is situated on the windward side of the ACSC.

Numerical simulation of heat transfer performance of an air-cooled steam condenser in a thermal power plant

The environmental wind speed, wind direction, and surroundings of the air-cooled condenser are parameters that may affect the cooling system performance. This article concentrates on the hot air recirculation phenomenon and its dependence on ambient winds are numerically simulated using the computational fluid dynamics code, FLUENT. In this study, two different wind directions (cases A and B) and two different wind speeds are considered. Results show that the hot air recirculation increases with the increment of velocity speed. Case A has a critical wind direction angle. Wind causes an air temperature increase at the fan inlet due to hot air recirculation, resulting in the deterioration of the heat transfer performance. In case A, fan inlet temperature is about 2.2 °C higher than fan inlet temperature in case B. Heat rejection in case B is 10.5% higher than case A. Increment of the wind speed from 3 to 9 m/s leads to 5.9 °C rise in fan inlet temperature and heat rejection reduction about 27%. The effect o...

Computational fluid dynamics simulation on a thermal power plant with air-cooled condenser

Managing the hot air recirculation and flow pattern in air-cooled systems is essential for satisfactory performance and reliable operation of compressor units. In this study, a numerical analysis of the exhaust air from an air-cooled compressor package located in oil and gas offshore platform is presented using computational fluid dynamics. The results of the analysis reveal that hot air recirculation can have a direct impact in air-cooled units, which is associated with the installation arrangement of the mechanical packages involving air coolers and the environmental conditions around the units. The results were able to predict flow and temperature fields in the compressor area, and provided recommendation to avoid exhaust air recirculation, which if not addressed and prevented can greatly reduce the cooling effectiveness of the air coolers leading to less reliable systems.

Numerical Analysis of Hot Air Recirculation Phenomenon in a Compressor Unit and Prevention of Overheating

The numerical simulation of conventional air-cooled unit and a new air-cooled one in which the incoming air is swirled by adding a swirler under the different angles of vane in the swirler has been made by employing actual data of Longshan power plant based on FLUENT software. Flow fields of the two kinds of units are obtained and compared. The most appropriate angle of vane in the swirler for heat transfer is found out. Optimums of heat load and heat transfer area are obtained and validated eventually by changing the head load and heat transfer area in the numerical simulation.

Numerical Simulation and Optimization on Air-Cooled Unit with Swirl Flow

The hot air recirculation phenomenon observed in direct air- cooled system is numerical simulated and the causes of the hot air recirculation and its influence on air-cooled units are qualitatively analyzed with the help of computational fluid dynamics (CFD) software. The results indicate that the hot air recirculation is a common trouble in the air-cooled power units. It is provoked by the arrangement of the air-cooled island and the environmental condition around the direct air-cooled system, especially the strong wind. The hot air recirculation greatly reduces the heat transfer ability, which will worsen units' vacuum and cause the power units to trip out.

Wensheng Zhao

Papers

Numerical simulation and analysis of the hot air recirculation phenomenon observed in direct air-cooled system

Research on dehumidification optimization of steam turbine wet steam stage hollow stator cascade heating