University of Tehran Journal of Solar Energy Research 2588-3097 11 1 2026 01 01 Innovative Multistage Solar Parabolic Trough Collector: Design, Development, and Thermal Performance 2820 2834 105833 10.22059/jser.2026.403441.1644 EN Sajjad Ashour Kadhim Chemical Engineering Department, Al-Nahrain University, Baghdad, Iraq Vinous Majeed Hameed Chemical Engineering Department, Al-Nahrain University, Baghdad, Iraq Journal Article 2025 10 02 Reliance on fossil fuels has led to severe environmental challenges that require more intensive development of clean energy alternatives. A design and experimental evaluation of a novel multistage parabolic trough collector (PTC) set under Basra City’s climatic conditions, southern Iraq, is presented. Four interconnected parabolic channels were designed to enhance cumulative heat gain while reducing the construction installation space. A corrugated copper tube receiver is used to increase the heat transfer surface and induce flow turbulence. A single-axis solar-tracking system was added to maximize incident solar radiation, with water flow rates of 3, 5, and 7 L/min. Conducting experimental results indicated that increasing the water flow rate reduced the outlet water temperature. The temperature gain was enhanced by 24%. The maximum temperature gain of 19 °C was recorded at 3 L/min, whereas the minimum was recorded at 7 L/min. Conversely, thermal efficiency increased with flow rate, reaching 82% at 7 L/min, corresponding to an improvement by 15-18%. The heat transfer coefficient was boosted up to 35%. The pressure drop was measured between 0.42 and 0.53 bar. These findings confirm the potential of the new design to enhance efficient energy capture, and a quantitative comparison with the traditional single-stage SPTC. https://jser.ut.ac.ir/article_105833_db5a61368e8b3fbb3463a5faa9f5d771.pdf