Session: 08-04-02: Sustainable Energy Systems for Heating and Cooling

Paper Number: 112995

112995 - Computational Fluid Dynamics Study of the Performance of Solar Air Heater 

As a part of the push for suitable and accessible green energy, renewable sources have become prevalent in both commercial and residential spaces. With the development of green technologies and the shortage of accessible renewable energy sources, the need for alternative methods of residential heating systems has increased over the past decades. Solar panels are one of the most promising forms of residential power generation. While widely used, significant losses are incurred when converting solar radiation into electric potential. Solar air heaters, commonly referred to as SAH, remedy the issue of conversion losses by utilizing solar radiation to warm air directly, without the use of photovoltaic cells. A typical SAH is a passive system that includes a flow channel encased in an insulated chamber, a transparent cover, and a solar collector to retain thermal energy. Inside a SAH, air passes over a high-temperature, sun-heated surface and is then returned to the living space at a higher temperature. Due to its availability and easy installation, SAHs could serve as a reliable supplemental heat source for individual rooms. For example, a home addition, workshop, garage, or any other small outbuilding could see their heating load reduced with the application of a SAH. While losses are reduced due to the conversion of energy, the properties of air and insulation requirements pose challenges. Unlike the design seen in a solar water heater, the low density and specific heat of air result in a challenging environment to impose a significant temperature change. Targeting these challenges, in this research, we use computational fluid dynamics analysis to find the optimal design of the SAH. We focus on the internal geometry of the SAH, in which the heat exchanges between the hot panel and cold air flowing over it. The changes in the internal geometry could improve the flow field to generate a smoother flow and enhance the rate of heat transfer between the two bodies. To quantitatively investigate how the internal design could affect their performance, SAHs with different internal geometries were designed. First, we modeled the three-dimensional SAHs with "S-shaped”, “Tight-shaped”, “Dual Channel-shaped” and “Dual Channel-Tight-shaped” internal structures in Solidworks. Second, the flow and heat transfer inside the designed 3D models were simulated and evaluated with Solidworks Flow Simulation. Results show that the configuration of the SAH has a great impact on its performance and a well-designed SAH could improve the performance by up to 10%.  Finally, we further developed a real-sized SAH and conducted experiments to validate the findings from the CFD analysis. The results from CFD and experiments show to have good agreement. This research could provide guidance for the optimal design of the next-generation SAH, and further enhance the sustainability of building designs.

Presenting Author: Kieran Ames Portland State University

Presenting Author Biography: Undergraduate Mechanical Engineering student at Portland State University

Authors:

Kieran Ames Portland State University
Chris Mccarthy Portland State University
Ian Clark Portland State University
Justin Weathers Portland State University
Kyle Mastrandrea Portland State University
Timothy Tudor Portland State University
Faryar Etesami Portland State University
Xiaowei Zhu Portland State University