Turbo-Assisted Direct Solar Air Heater for Medium Temperature Industrial Processes Using Linear Fresnel Collectors. Assessment on Daily and Yearly Basis

Abstract The study analyzes an innovative concentrating solar thermal system aimed at the direct production of hot air for industrial applications. Air is heated inside linear Fresnel collectors in an open to atmosphere circuit, not requiring the use of a primary heat transfer fluid and a heat exchanger, with their associated cost and maintenance. Matching an automotive turbocharger with the solar field avoids auxiliary energy consumption for pumping the airflow. The detailed quasi-steady numerical model implemented, including commercial collector and turbocharger technical features, allows to scrutinize the daily and yearly operating time profile of a medium scale plant with a 633.6 m2 solar field. Considering the typical meteorological year of the selected location (Madrid, Spain), the numerical results indicate that hot air is provided at a remarkable quasi-constant temperature between 300°C and 400°C despite the solar variations, delivering 330 MW hr per year without overheating the receiver evacuated tubes.