Ch., Sreenivasa Rao, and Gupta AVSSKS. “Thermal Efficiency Improvement of Direct Absorption Solar Collector Using TiO2- Water Nano Fluid”. International Journal of Engineering and Innovations 1, no. 1 (December 1, 2019): 27-32. Accessed July 6, 2020. http://ijei.in/index.php/ijei/article/view/3.