Hussam S. Dheyab, Manar Salih Mahdi Al-Jethelah, Tadahmun Ahmed Yassen and Thamir Khalil Ibrahim 2024. Experimental Study of The Optimum Air Gap of a Rectangular Solar Air Heater. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences. 59, 2 (Mar. 2024), 318–329.