ACSC Performance with Diffuser Orifice Plate, Validation

ACSC Performance with Diffuser Orifice Plate, Paper Numerical Validation, ANSYS Fluent CFD Simulation Tutorial

This project simulates the ACSC system in a 600 MW power plant based on the article “Effects of a diffuser orifice plate on the performance of air-cooled steam condenser.” The results of the current numerical CFD simulation work are compared and validated with the reference paper by ANSYS Fluent software.

The main purpose of designing and using these systems in power plants is to prevent energy waste; In this way, these systems condense the hot steam from the turbine and transfer the water from the distillation process to the pump section of the steam turbine.

The power plant studied in the present work consists of 7 rows of ACSC systems. The fourth row is studied in this CFD simulation. Each row of ACSC systems consists of eight fans, and each of these fans is located under two diagonally porous plates.

The operation of these systems is such that the hot and low-pressure steam of the turbine outlet passes through each of the pipes and then is transferred to the interior space of the diagonal plates installed on both sides of that pipe.

The present 3-D model is designed using SOLIDWORKS and Design Modeler software. The geometry is related to a cooling system consisting of eight rows of hot steam pipes, diagonally porous plates on either side of each pipe, and eight fans on one platform.

The meshing of the present model is done using ANSYS Meshing. The mesh type of the model is hybrid, and the element number is 2668772.

ACSC Methodology

The purpose of the problem is the distillation process; Therefore, a constant saturation temperature for steam must be defined; Because the condensation process takes place at saturation temperature at a constant pressure. This value is 319.75 K.

Also, the fan boundary condition is considered for each of the eight installed fans. In the Fan boundary condition, a pressure jump must be used; Because there will be a pressure difference on both sides of the fan in the specified direction.

The amount of pressure jump is obtained based on a polynomial function in terms of the axial velocity passing through the fan surface; Hence, a polynomial is imported in this section.

ACSC Conclusion

After simulation, the 3D contours related to the velocity, pressure, and temperature are obtained. The temperature contour shows that the open air transfers its heat to the steam pipe for condensation to occur.

Also, The graph of volumetric effectiveness changes in terms of the fan number in the system is obtained and validated with the results of the source paper.

The diagram under consideration in the article is related to Figure 5-c. The main purpose of this work is to investigate the effect of open airflow velocity on the performance of the fans of the system in terms of volume transfer from the cooling airflow.

Then, a dimensionless parameter is defined to investigate the volumetric flow rate of the fans. This parameter is equivalent to the ratio of the volumetric flow rate transferred from the fans resulting from the numerical solution to the volumetric flow rate flowing from the fans in the ideal state.

The ideal volume flow rate is 428 m.s-1, and the dimensionless parameter is called volumetric effectiveness. A comparison between the results of the present work and the results of the article confirms that the accuracy of the solution is acceptable, and the error is low.