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Received: 27 November 2022. Accepted: 3 April 2023. It is a pleasure to appreciate the General Director of Scientific Research Center at Erbil Polytechnic University Asst. Prof. Dr. Hayman Kakakhan Awla and his colleagues for their technical supports and help. Also, all authors express their appreciation to Asst. Prof. Dr. Nazar Faraj Antwan for his valuable scientific advice. Flat Plate Solar Collectors (FPSC) are one of the most environmentally friendly and energy-efficient heating solutions. In this work, the thermal performance of the FPSC for a greenhouse heating system was experimentally and numerically investigated by utilizing distilled water as a working fluid and Al2O3-water nanofluid with two different nanoparticle concentrations of 0.2wt.% and 0.5wt.%. The simulation model was conducted using TRNSYS 18, and its outcome was validated with experimental results. As a first step, the study estimates the maximum required amount of energy for a greenhouse in the Scientific Research Center at Erbil, Iraq. A temperature of 23℃ was selected as a set point temperature in the greenhouse, which is essential for the experiments needed for developing several plants. The most interesting finding was that when nanofluids were used as a working fluid, the efficiency gain was larger than with water only. The highest collector efficiency was attained when 0.5wt.% nanofluid was used in the FPSC, which increased the collector efficiency by 17.5% over the water case. Additionally, FR (UL) values for Al2O3-nanofluid and water are approximately close to each other, while for all applied concentrations, Al2O3-nanofluid's FR (τα) values were more significant than water. Further analysis showed that, during the coldest months of the year, the system could raise the inner air temperature of the greenhouse, which is ideal for farming applications. |
