ACSC Performance with Diffuser Orifice Plate: Paper Validation

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

Description

This project simulates an air-cooled steam condenser (ACSC) system within a 600 MW power plant, based on the reference article "Effects of a diffuser orifice plate on the performance of air-cooled steam condenser," with results compared and validated against the paper's published data using ANSYS Fluent.

ACSC systems are designed primarily to prevent energy waste in power plants — they condense hot steam exiting the turbine and transfer the resulting water from the distillation process back to the steam turbine's pump section. The power plant modeled in this study consists of seven rows of ACSC systems, with this simulation focusing specifically on the fourth row. Each row contains eight fans, with each fan positioned beneath two diagonally oriented porous plates. During operation, hot, low-pressure steam exiting the turbine passes through a series of pipes and is transferred into the interior space bounded by the diagonal plates installed on either side of each pipe.

The 3D geometry was built using SolidWorks and Design Modeler, representing the cooling system's eight rows of hot steam pipes, the diagonal porous plates flanking each pipe, and the eight fans mounted on a single platform. The domain was meshed in ANSYS Meshing using a hybrid mesh totaling 2,668,772 elements.

Methodology

Since the core objective involves the distillation process, a constant steam saturation temperature of 319.75 K was defined, reflecting that condensation occurs at saturation temperature under constant pressure. Each of the eight fans was modeled using the fan boundary condition, which requires specifying a pressure jump to represent the pressure difference generated across the fan along its defined direction. This pressure jump was defined through a polynomial function relating it to the axial velocity passing through the fan surface, imported directly into the fan boundary condition setup.

Conclusion

Results include 3D contours of velocity, pressure, and temperature. The temperature contour confirms that ambient air absorbs heat from the steam pipes, driving the condensation process as intended.

A graph of volumetric effectiveness versus fan number was also extracted and validated against Figure 5-c of the reference article. The study's central objective was to examine how ambient airflow velocity affects the system's fan performance in terms of volumetric transfer from the cooling airflow. To quantify this, a dimensionless parameter — volumetric effectiveness — was defined as the ratio between the volumetric flow rate delivered by the fans in the numerical solution and the ideal volumetric flow rate of 428 m³/s. Comparing this result against the reference paper's data showed acceptable solution accuracy with low error, confirming the simulation faithfully reproduces the reference system's performance behavior.