A comprehensive review of design parameters, thermal performance assessment, and medium temperature solar thermal applications of Scheffler concentrator

Abstract

Decentralized renewable energy sources such as solar thermal energy with diversified applications help to mitigate fossil fuel requirements and trigger new technology development. Fixed focus Scheffler concentrator offers thermal applications which are presently being met by conventional heaters powered by grid or steam generated using fossil fuel-fired boilers. The Scheffler concentrator developed by the German scientist Wolfgang Scheffler is attractive because of various advantages like simplicity of construction and easy access to hardware materials to build the system. Overall, it is an open-source model. This paper provides a comprehensive review of the use of such a solar concentrator. The first part describes the complete working principle, design aspects, and the tracking mechanism. The concentrator, a small lateral section of a large paraboloid, has a simple mechanical tracking system to rotate the disc in the direction of the sun’s movement. The study next assesses the application of the concentrator for medium temperature requirements up to 150–300 °C, which includes community cooking, laundry, desalination, brick & POP making, water heating, steam generation, extraction of essential oil, and even cremation, amongst many others. The performance assessment of the concentrator carried out through modeling, and experimental investigation is discussed subsequently. There are, nevertheless, several limitations of the Scheffler concentrator technology. These include vast space requirements, high cosine losses, difficulty in reaching temperatures >300 °C, single-axis tracking, and high maintenance cost. These gaps can open up new research areas for the spread of this environmentally benign technology, particularly in sunny regions of the world.