Evaluating the Impact of Recycled Ceramic-Pcm Compound and Absorber Tube Positioning on the Efficiency of Flat-Plate Solar Collector

Abstract

Hot water production remains highly dependent on finite fossil fuels, contributing to environmental degradation and resource depletion. Solar energy presents a cleaner, sustainable alternative, with flat plate solar water heaters (FPSWH) widely recognized for their affordability and reliability. Integrating thermal energy storage (TES) systems enhances energy absorption, while phase change materials (PCMs) show promising potential for improved storage efficiency. Recycled ceramic (RC) offers a cost-effective, eco-friendly storage option, but its low heat capacity constrains performance. Combining RC with PCMs creates hybrid materials with enhanced thermal properties. This study deployed a small-scale system with two heat exchanger scenarios (upper and lower bounds) and two TES material configurations: pure PCM (RT31) and a recycled ceramic-PCM composite.Key findings from experimental analysis during radiation on and off cycles revealed that the PCM in lower-bound configurations (L-PCM and L-RC-PCM) did not fully melt, indicating effective thermal energy absorption. System efficiency peaked at 37-38% for L-PCM and L-RC-PCM with rapid fluctuations, whereas upper-bound configurations (U-PCM and U-RC-PCM) showed lower, more stable efficiencies of 27-30%. Lower-bound heat exchanger positioning increased cumulative energy gain by approximately 12%, while upper-bound configurations reduced it by 3.6% and 5.3% compared to the conventional flat plate collector.The study shows that inserting the heat exchanger tube into the TES material has a better impact on the system performance than changing the storage capacity of the material.

Keywords: Flat plate solar collectors, thermal energy storage, PCM, recycled ceramic, heat exchanger tube positioning