Material Failure Analysis and Selection Criteria for PCM-Integrated Solar Flat Plate Collectors

Abstract

Present research paper is depicting the challenges to make a leak-proof solar flat plate collector (FPC) containing Phase-change material (PCM).A lot of leakage problem in PCM panels was observed during the fabrication, testing and experimental work; therefore, efforts have been made to prevent leakage in PCM panels by using different types of sealants and different materials. The best leak proof results were obtained by iron tube in which rubber gasket is inserting at the opening and covered through the iron gasket using Teflon tape. Two solar water heaters have been designed and fabricated with compact type boxes of size of 24\"×16\"×4\", one with conventional FPC and the other with PCM.A simple water heater heats water up to 70?C by 12 noon, while a PCM filled collector heats water up to 95?C by 12 noon and continues heating water even after sunset. It was observed that even at 10 pm it continues to heat water up to 40 ?C. Therefore, it can be concluded that solar FPC showcases better efficiency and reliability with PCM as compared to conventional FPC. The integration of phase change materials (PCMs) into solar flat plate collectors offers significant advantages in thermal energy storage, improving efficiency and energy retention. However, operating conditions can cause the material to fail, affecting performance and longevity. This study explores various failure mechanisms, including thermal stress, mechanical degradation, and chemical instability. It also discusses non-destructive evaluation methods as well as advanced diagnostic techniques such as thermal, mechanical, and chemical analysis. Mitigation strategies, including material selection, design optimization, protective coatings, and improved PCM formulations, have been proposed to enhance system reliability.

Introduction

The text discusses the development and failure analysis of a solar flat-plate water heater integrated with phase change materials (PCM) to improve hot water availability for rural households, where water quality and hygiene are often inadequate. Hot water is essential for daily activities such as cooking, bathing, and cleaning, and rural households typically require 120–150 liters of potable water per day. Since hot water demand extends beyond daylight hours, integrating PCMs into solar collectors helps store thermal energy and supply heat after sunset.

The study focuses on a copper flat-plate solar collector with PCM for latent heat storage, highlighting challenges related to material failures caused by thermal expansion, mechanical stress, and chemical incompatibility. PCMs, which store and release heat during phase transitions, enhance energy efficiency but can cause leakage and structural degradation if not properly contained. Various types of failures—mechanical deformation, chemical corrosion, and sealing breakdown—are identified as major limitations of PCM-based systems.

Two types of collectors were fabricated and tested: a conventional copper foil–tube collector without PCM and a PCM-filled collector using iron pipes embedded within copper foil sheets. Detailed fabrication methods for insulated iron boxes, copper foil–tube panels, and PCM-filled panels are described. The experimental setup involved outdoor testing with controlled water flow, temperature measurements, and efficiency calculations over several days.

Extensive failure analysis was conducted using different sealing materials and containment methods. Many materials such as PVC pipes, rubber tubes, gaskets, and pouches failed due to leakage under high temperatures. Ultimately, iron pipes combined with silicone sealant and Teflon tape proved effective in preventing PCM leakage, resulting in a leak-proof PCM-filled solar water heater design.

Experimental results showed that the conventional collector achieved water temperatures up to 70 °C at noon and 55 °C in the evening, demonstrating its viability as a low-cost option. Overall, the study concludes that integrating PCM into solar flat-plate collectors can enhance thermal storage for rural water heating, provided that appropriate materials and sea

Conclusion

Material failure analysis is critical to improving the performance and durability of PCM-filled solar flat plate collectors. By understanding the failure mechanisms and employing proper failure techniques, manufacturers can design systems that can withstand operational stresses. The used method includes a low-cost assembly, which performs continued examination of the degradation of solar copper flat plate collector. It is observed that solar FPC is feasible for long-term use. There was a lot of leakage problem in PCM panels during the experiment; hence efforts have been made to prevent leakage in PCM panels by using different types of sealants and different materials. By combining it with an iron tube, its test was successful and it could be used. Two flat plate collectors were built for testing; these can be easily multiplied to make larger flat plate panels. While performing experiment, problems related to PCM filling in iron tubes was encountered. This made it difficult to quantify further investigation. The experiment covers several complementary assembly methods, such as creating a cheaper design by removing the copper tube. By using a good sealant with low cost, it will become much easier to manufacture SFPC using limited resources.

References

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Copyright

Copyright © 2025 Haneef Khan, Dr. Ravindra Randa, Prof. Brijendra Kumar Gond. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.