Enhanced Solar Energy Harvest for Power Generation From Brayton Cycle

Abstract

A scalable and modular solar thermal dish-Brayton system is proposed in response to growing demand for renewable energy and distributed power generation. Existing dish systems require large areas to achieve sufficient conversion efficiency for the cost of the system. Also, the conversion efficiencies are limited by the materials and manufacturing processes. This paper proposes a low cost, high efficiency solar absorber as the core of a dish-Brayton system with the capability to achieve much higher operating temperatures than current absorbers. A simple cylindrical part, forming a black body cavity, is fabricated from silicon carbide for high absorptivity at a low fabrication cost. The manufacturing process consists of a simple casting and sintering procedure, which is a common way of creating ceramic parts. Another cylindrical shell is fabricated to cover the outer surface of the black body cavity, creating a channel for air to pass through. The high thermal conductivity of the silicon carbide ensures the efficient heat transfer between the solar absorber and the air. The entire solar energy absorber is designed to heat air up to 1500 K, which would improve energy conversion efficiency of concentrated solar power generation based on 1270 K by 20%. Analysis and test results on a scaled device are presented.