CFD-Based Study of Performance Enhancement of a Solar Chimney Using Synthetic Jets

Abstract

In the past few decades, excessive carbon emissions have had a significant impact on the earth, such as global warming, leading to the reduction of icebergs and sea level rise. Therefore, many scholars have turned their attention to new energy sources, hoping to find ways to reduce carbon emissions. Solar chimneys are one of the devices that use 100% renewable energy. Like most devices driven by new energy sources, the ventilation performance of solar chimneys is not as good as that of traditional electric-driven ventilation systems. Therefore, improving the ventilation performance of the chimney is a top priority. In addition to changing the chimney design, adding an airflow control device is also an excellent way to improve performance. Synthetic jet (SJ) is an active flow control method that has the advantages of easy installation, simple structure and low cost. It stands out among many control devices and it is a good choice. Many scholars have studied the synthetic jet as an active fluid control device for separation flow control on the aircraft wing. This article will use the data obtained in CFX (a CFD software) to study the feasibility of the design. First, there will be a discussion of the influence of the chimney design on the chimney performance, including the heating plate, inlet position and the ratio of the inlet and outlet. This part will use the Shear Stress Transport (SST) model to calculate, and the subsequent experiments on SJ will use the k-Epsilon (k-ε) turbulence model. The fluid characteristics produced by an 18-inch loudspeaker as SJA will be discussed later. The effects of different amplitudes and vibration frequencies on the fluid flow field are studied. Simultaneously, the influence of the varying orifice geometries on the performance of SJA has also been studied. Finally, the two models are merged and simulated with the k-ε model. The result is that if the amplitude of the SJA is too small (0.5mm), the performance of the chimney does not rise it decreases. If the amplitude is 7mm, the chimney's performance can be improved by about 3 percent.