MAINSTREAM ENGINEERING CORP SBIR Phase I Award, July 2023

Relatively low operating temperatures of proton exchange membrane fuel cells (PEMFCs) necessitate large thermal management systems (TMS). For PEMFCs to be a viable replacement for diesel engines in heavy-duty vehicles (100-450 kW power range), novel compact heat exchangers (HEXs) must be developed to reduce the size, weight, power, and cost (SWaP-C) of the TMS. Rather than rely on larger fans with their associated SWaP penalty, Mainstream proposes to leverage our experience in advanced compact HEX design to develop a radiator and stack cooling plates that maximize heat transfer surface area with low pressure drop on the air- and fluid-sides, thus delivering comparable cooling capacity for the same fan power. We will consider HEX geometries such as round and non-round microtubes, microchannels, and innovative tube/fin configurations to improve HEX performance. In Phase I, Mainstream will design and optimize radiator and fuel cell stack HEXs using commercial and in-house computational tools and models. We will investigate the impact of environmental conditions such as dust and corrosion to evaluate the tradeoffs between theoretical performance and mid- to end-life performance in harsh operating environments. We will improve manufacturing methods and demonstrate their effectiveness on the subscale. We will experimentally demonstrate subscale HEXs based on the design in Phase I. In Phase II, we will fabricate and full scale HEXs and test them in PEMFC systems. The proposed solution has many benefits in industrial and commercial applications. The direct result of this technology will be to improve the overall efficiency and reduce total costs of heavy-duty PEMFC electric vehicles paving the way for greater adoption of fuel cell technologies and reducing our dependance on fossil fuels. In addition to enabling PEMFC vehicles, our compact radiator technology is widely applicable to the automotive industry.