Performance enhancement of solar updraft tower plant using parabolic chimney profile configurations: A numerical analysis

Abstract

The solar updraft towers harnessing solar energy are a sustainable and economical source of power, however, they suffer from low collector efficiency. Geometric characteristics have a large effect on the plant’s efficiency. One of the lesser-studied parameters that affect the flow behavior, and the performance of the plant is the chimney wall profile. A novel concept of parabolic wall profiles is introduced in this study using inner parabolic chimney profile (IPCP) and outer parabolic chimney (OPCP) configurations. For this purpose, the plant is modeled numerically and validated with the experimental data from the Manzanares prototype. The influence of parabolic profiles is studied at 0° to 3° chimney diverging angle (CDA) and 0° to 10° collector roof angle (CRA). The convergent effect of IPCP resulted in increased performance in contrast to OPCP. The appearance of large eddies creating a recirculation region near the base of the chimney is significantly decreased by using IPCP. The IPCP also resulted in an elevated performance when the effect of CDA and CRA is included resulting in a 12.1% increased power output. The IPCP at 1° CDA and 6° CRA is found to be the optimum among the studied configuration resulting in 80.6% and 80.7% increased power output and collector efficiency respectively. The proposed design resulted in smoother flow with smaller eddies, better thermal characteristics, and improved performance of the plant.