Case studies on the effect of two-dimensional heliostat tracking on the performance of domestic scale solar thermal tower

Abstract

Solar thermal system has been envisioned for utility scale applications. However, on the low end the domestic applications can be made realizable through low end automation. Performance of typical solar reflector can be significantly enhanced by using a solar tracking system. An efficient & low energy consuming system can result in improved energy harvesting. In the current study, an experimental analysis of automated domestic scale heliostat field using rack and pinion-based mechanism is performed. The mechanism is controlled using relay module with an Arduino UNO R3-SMD. Experiments are performed in actual working conditions of Taxila, Pakistan. The heliostat field is made to reflect the solar rays to a cavity type central receiver (CTCR) having stainless steel tubing. Experimentations were performed under three different scenarios-tracking using one dimensional (1D) with fixed position heliostats, tracking using two dimensional (2D) with 5 variable positioning heliostats, and tracking using 2D with 8 variable positioning heliostats. The performances of each setup is analyzed parameters such as heating fluid, temperature difference (ΔT), absorbed heat (Qabs), and overall efficiency (ƞ). Performance enhancement was observed using 2D tracking with 8 variable positioning heliostats where ΔT was 64.26 °C, Qabs was 489.89 W, with maximum ƞ was 52.8%. In 2D with 5 variable positioning heliostats and 1D with fixed heliostats, the values obtained were 50.3 °C, 385.5 W, 51.83% and 6.523 °C, 50 W, 45.86% respectively.