Thermal Assessment and Performance Evaluation of Evacuated Flat Plate Collector

Abstract

The transition towards renewable energy technologies is gaining momentum, especially within industrial domains seeking sustainable alternatives to traditional energy sources. Among these technologies, the Evacuated Flat Plate Collector (EFPC) stands out as a promising solution, amalgamating the advantages of both Flat Plate Collector (FPC) and Evacuated Tube Collector (ETC). This thesis delves into an in-depth performance analysis of EFPC. Utilizing a meticulously validated mathematical model, the study explores the study of three crucial design parameters—tube diameter, spacing, and absorber plate thickness—while investigating their impact on four key performance indicators: outlet temperature, overall heat loss coefficient, thermal efficiency, and exergy efficiency. It has been found that for an industry where daily 500 tons water is heated from 25°C to 100°C, the tube diameter should be around 12 mm and the distance between the tubes should be around 180 mm to get the maximum performance from the collector. The optimum absorber plate thickness should be around 0.2 mm for the mentioned case. Through rigorous energy and exergy analyses, the study elucidates the sensitivity of these parameters to fluid temperature, flow rate variations, and solar irradiance fluctuations across different seasons, thereby providing comprehensive insights into EFPC's performance under diverse climatic conditions. Energy and exergy analyses conducted under varying environmental conditions provide valuable insights into the operational efficiency of EFPC. By simulating different inlet fluid temperatures, flow rates, and solar irradiance levels, the study demonstrates the collector's adaptability to various boundary conditions. In the studied case, the thermal performance significantly improves with increasing flow rates up to approximately 0.003 kg/s, beyond which the improvement becomes negligible. Analysis indicates that the current system operates optimally when the inlet temperature is below 350K. If the inlet temperature surpasses this threshold, both thermal efficiency and exergy efficiency decrease, adversely affecting the system's overall performance. From off design performance analysis, it has been observed that during summer, higher solar irradiance enhances the collector's performance, while in winter, the efficiency drops slightly due to lower irradiance levels. However, EFPC maintains a relatively high efficiency across all seasons, making it a reliable choice for continuous industrial applications. The economic analysis of EFPC highlights its potential for significant cost savings. By supplying a substantial portion of the heat demand, EFPC reduces reliance on conventional energy sources, leading to lower fuel costs. The daily savings of 45.57%, when extrapolated over a year, translate to considerable financial benefits for the industry. Additionally, the reduction in CO2 emissions by up to 3.915 tons in summer underscores the environmental advantages of adopting EFPC technology. This aligns with global efforts to reduce carbon footprints and combat climate change, making EFPC an attractive option for industries aiming to achieve sustainability goals. In addition to its performance analysis, EFPC's comparative advantage over traditional FPC and ETC collectors is underscored, positioning it as a superior choice for industrial applications. It is notable that when the inlet temperature is 340 K, the exit temperature of the FPC is 341.33 K, indicating that FPC is not recommended for higher temperature applications. Both EFPC and ETC outperform the FPC at higher inlet temperatures, with no significant difference in performance between EFPC and ETC. At lower solar irradiation, the thermal efficiency of the FPC is significantly lower compared to EFPC and ETC. However, as solar irradiation increases, the thermal efficiency of the FPC also increases, reaching 81.89% at 1000 W/m². ETC demonstrates the highest thermal efficiency at around 82.7%, followed closely by EFPC with a deviation of approximately 1%. The study extends its scope to explore EFPC's integration into the Absorption Refrigeration Cycle (ARC), highlighting its versatility and potential for sustainable energy solutions across various industrial sectors. By offering assessment of EFPC's performance, economic viability, and environmental impact, this research contributes to the broader understanding of solar energy utilization and aids decision-making processes for implementing sustainable energy solutions in industrial contexts. This research provides a detailed evaluation of EFPC, emphasizing its technical, economic, and environmental benefits. The findings support the adoption of EFPC in industrial settings, highlighting its potential to enhance energy efficiency, reduce costs, and mitigate environmental impact. Future studies should focus on long-term performance monitoring and explore the integration of EFPC with other renewable energy systems to further optimize its application in various industrial processes.