Effect of Collector Self-Shading on the Performance of a Biomass/solar Micro-Chp System
Abstract
This paper describes an exhaustive study concerning solar geometry and the effect of shading between collectors in the overall performance of a new biomass/solar micro-CHP system. The system is a new prototype of a 6 kWe plant, based on a micro-cogeneration Organic Rankine Cycle (ORC) system, driven by a combination of solar thermal and biomass sources. Both sources may be used separately or combined. The solar thermal energy is obtained through medium-temperature concentrating compound parabolic solar collectors (CPC) with evacuated tubes. The system simultaneously produces electrical energy and low/medium temperature heat. In this study, five scenarios are presented: no shading; shading when the collector tilt is seasonally adjusted; and shading when the collector tilt is fixed in three positions during the year. Results of system simulation under the different operating modes are presented. Namely, a comparison of solar fractions and global electrical efficiencies of the system, with and without shading, is carried out.
Keywords
Collector shading, Organic rankine cycle, Micro-cogeneration, Solar energy, Biomass