Flat plate solar collectors comprise a flat, rectangular panel with a transparent cover, an absorber plate, and insulation. The cover allows sunlight to pass through and reach the absorber plate, which converts it into heat energy. The heat is transferred to a fluid that flows through tubes or channels within the collector, usually water or a heat transfer fluid. The heated fluid has many applications, including domestic hot water heating, space heating, pool heating, industrial process heating, and solar drying. They provide a sustainable and eco-friendly method of harnessing solar energy, offering an alternative to traditional energy sources and helping to decrease greenhouse gas emissions.

In this project, we utilize a solar ray tracing model to simulate the performance of a flat plate solar collector in Ukraine. The specific geographical coordinates chosen for the simulation are a latitude of 51.531 and a longitude of 25.2854. Furthermore, the paper entitled “Energy and exergy comparison of a flat-plate solar collector using water, Al2O3 nanofluid, and CuO nanofluid [1]” is chosen as the base paper to follow and take correct estimated inputs.

• 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: Flat plate solar collector CFD simulation [1]

Simulation Process

The geometry of the present model seems to be easy to be drawn using ANSYS Design Modeler software. However, due to the use of a structured grid for higher accuracy, it becomes a challenge to split zones in the primary phase of the project. The design model is meshed in ANSYS Meshing software, and 792000 hexagonal cells are formed (Figure 1). The flat plate solar collector has different parts, including an insulated substrate, an absorber made from aluminum, a copper tube and water that flows inside it. In order to consider radiation effects, the Discrete Ordinates (DO) module is activated along with Solar Ray Tracing model to estimate received radiative solar irradiation from the sun in December. The k-epsilon RNG turbulence model is also used. Each part of the system has its own specific thermal condition, which requires a great understanding of the mechanism of the solar collectors.

Figure 2- The structured grid generated for model

Post-processing

An extensive relationship between radiative and conductive heat transfer mechanisms is shown by the thermal performance analysis of the flat plate solar collector. The interaction between the incident solar radiation and the collector components is well captured by the Solar Ray Tracing model in association with the Discrete Ordinates (DO) module. With the insulation substrate reaching high temperatures of 354K, the temperature distribution contours demonstrate a strategic thermal cascade, which amply demonstrates the system’s efficient solar energy capture. This temperature pattern shows how the high thermal conductivity materials (copper tubing and aluminum absorber) enable effective heat transfer to the working fluid, while the insulation layer’s non-reflective quality aids in thermal energy retention.

Figure 3- Temperature Distribution on a 2D section plane

The thermal evolution of the working fluid offers strong proof of the system’s efficiency in using solar energy. Through a single pass, the water’s temperature rises significantly from its initial entrance temperature of 45°C to 54.87°C, or 22%. The design of the collector and the numerical method, in particular the use of the k-epsilon RNG turbulence model for fluid flow characterization, are both validated by this significant temperature gain. Optimal thermal energy transmission from the absorber plate to the working fluid is indicated by the temperature contours on the 2D section plane, which show consistent heat distribution throughout the collector with maximum temperatures strategically centered around the fluid channels. The simulation’s geographic specificity (latitude 51.531°, longitude 25.2854°) gives these results more real-world significance and shows that the system is feasible for solar thermal applications in Ukraine’s environment.