Swirl Burst injector enables ultra-clean combustion of biofuels

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Researchers in the US have developed a method for the efficient combustion of biofuels using a Swirl Burst injector to burn glycerol/methanol blends with near-zero emissions.

Mechanical engineering professor Lulin Jiang, Ph.D., and her research team on the novel Swirl Burst injector inside the CAC Lab at Baylor University, Texas
Mechanical engineering professor Lulin Jiang, Ph.D., and her research team on the novel Swirl Burst injector inside the CAC Lab at Baylor University, Texas - Robert Rogers/Baylor University

Detailed in Fuel, the Swirl Burst (SB) injector at Baylor University’s Cornerstone Atomization and Combustion Lab (CAC) is claimed to enable ultra-clean combustion for fuels that are typically difficult to burn due to their high viscosity. 

According to the Texan university, conventional injectors struggle to burn glycerol – an abundant byproduct of biodiesel production – due to its high viscosity, though it has moderate energy density.

In contrast, the SB injector’s ability to handle glycerol without requiring costly fuel preheating or processing could transform biofuel economics. The process allows the SB injector to achieve a complete and clean burn by producing fine droplets, significantly reducing emissions of harmful pollutants like carbon monoxide (CO) and nitrogen oxides (NOx).

Lead author Lulin Jiang, Ph.D., principal investigator of the CAC Lab, said this novel technology also enables biodiesel producers to convert glycerol waste into a viable fuel source, promoting a circular economy and reducing the carbon footprint for generating power.

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According to the university, the SB injector’s flexibility allows the combustion of various glycerol/methanol ratios without hardware modifications, making it ideal for power plants aiming to meet emissions regulations.

“Being able to transform waste, such as waste glycerol, into cost-effective renewable energy promotes energy resilience and energy equity for economically disadvantaged groups in a changing climate,” Jiang said in a statement.

The research team tested three different fuel blends – 50/50, 60/40 and 70/30 glycerol to methanol ratios by theoretical heat release rate – at multiple atomising air-to-liquid mass ratios (ALR).

All blends are said to achieved over 90 per cent combustion efficiency including complete combustion by the 50/50 blend, with near-zero CO and NOx emissions, even in non-preheated, uninsulated combustion setups.

This is claimed to be a significant improvement over conventional air-blast or pressure-swirl injectors, which often generate high emissions with high-viscosity fuels.

“The demonstrated high viscosity tolerance and fuel flexibility of the technology signifies that not only waste glycerol, but also the viscous source oils of biodiesel, and other waste-based bio-oils can be directly utilised for energy generation without further processing, significantly reducing biofuel cost and thus potentially stimulating its broad application,” said Jiang.

biofuels