A flat plate solar collector is a simple but effective device for gathering energy. It consists of a rectangular box with a transparent glass cover on top and an insulated bottom. Inside, there is a metal “absorber plate” that catches sunlight. This plate gets very hot and transfers its heat to a fluid, usually water, which flows through copper tubes. This hot water is then used for homes, pools, or industrial heating. It is a clean way to produce energy and helps reduce pollution.

In this Flat Plate Solar Collector CFD project, we simulate the performance of a collector located in Ukraine. We use specific coordinates: Latitude 51.531 and Longitude 25.2854. This makes the simulation realistic for that specific location. We also use a research paper by Tong et al. (2019) as a reference to ensure our settings are correct. This ANSYS Fluent training demonstrates how to use advanced tools like the Solar Ray Tracing model to predict how well a collector works in winter.

• Reference [1]: Tong, Yijie, et al. “Energy and exergy comparison of a flat-plate solar collector using water, Al2O3 nanofluid, and CuO nanofluid.” Applied Thermal Engineering159 (2019): 113959.

Figure 1: Schematic of the flat plate solar collector components analyzed in the CFD simulation, based on the reference paper [1].

Simulation Process: Solar Ray Tracing and the DO Model in Fluent

To start this CFD analysis, we created the 3D model in ANSYS Design Modeler. The model includes the insulated bottom, the aluminum absorber, the copper tubes, and the water domain. Although drawing the geometry is straightforward, creating the mesh is challenging because we wanted high accuracy. We aimed for a “structured grid,” which means the cells are arranged in neat rows. We successfully generated exactly 792,000 hexagonal cells using ANSYS Meshing. Hexagonal cells are better than triangles because they give more accurate results for heat transfer problems. For the physics in ANSYS Fluent, we needed to simulate how sunlight moves. We activated the Discrete Ordinates (DO) radiation module. This module is essential for calculating how radiation travels through the glass and hits the plate. We also enabled the Solar Ray Tracing model. This specific tool calculates the sun’s position and intensity for December in Ukraine.

Figure 2- The structured mesh with 792,000 hexagonal cells generated for the solar collector model.

Post-processing: Thermal Performance and Efficiency Analysis

In this section, we explain the results of our Flat Plate Solar Collector CFD project. We look at the temperature pictures and the data to see if the design works well. The temperature contours on the 2D plane show a very clear heat pattern. The system captures solar energy efficiently. We can see that the insulation substrate at the bottom reaches a high temperature of 354 Kelvin. This is a very good sign. It shows that the insulation stops the heat from escaping out the back. Because the back is sealed, the heat stays inside. The materials we used, like copper for the tubes and aluminum for the absorber, conduct heat very fast. This helps move the energy from the plate into the water effectively.

Figure 3- Temperature distribution on a 2D section plane showing the heat transfer to the water.

Furthermore, the most important proof of efficiency is the water temperature. The simulation shows that the water enters the tube at 45°C. As it flows through the collector, it gets hotter. By the time it leaves, the temperature rises to 54.87°C. This is a 22% increase in a single pass. This result validates our use of the k-epsilon RNG model and the Solar Ray Tracing method. The contours show that the heat is spread out evenly, with the hottest parts right around the fluid channels. This confirms that the system is feasible and works well for solar heating in the environment of Ukraine.

Key Takeaways & FAQ

• Q: What is the Solar Ray Tracing model in ANSYS Fluent?
  • A: It is a tool that simulates real sunlight. You enter the location (Latitude 51.531) and time (December), and the software calculates the sun’s rays for your CFD simulation.
• Q:  Why is the Discrete Ordinates (DO) model used?
  • A: The DO model is used to solve the radiative transfer equation. In a solar collector CFD simulation, it is necessary to calculate how solar radiation passes through the glass cover and is absorbed by the plate.
• Q: How efficient was the collector in the simulation?
  • A: The water temperature increased from 45°C to 54.87°C. This is a 22% increase, which proves the collector works well.