Environmental problems such as air pollution have recently led to increasingly demanding emissions regulations.
To address this issue, the present study aims to develop a technology that will enable the exhaust gas from compact generators, with output of less than 3 kVA, to satisfy the world's most demanding emissions regulations.
The method we used is driven by pulsed secondary air injection with a catalyst. Whereas pump-driven methods have conventionally been the mainstream approach to attaining sufficient secondary air quantity to reduce emissions, our objective was to create a pump-free method for increasing the secondary air quantity by focusing on secondary air pipe pulsation.
Our study had two aims: one was to create a computation method for predicting the optimum secondary air pipe length that maximizes secondary air, and the other was to verify this method by using actual equipment, and to achieve our target emissions values.
Our testing verified that for the secondary air pipe used to amplify the secondary air quantity, the proposed computation method yielded a secondary air pipe length with strong correlation to our measured results.
By using our study results to determine the proper secondary air pipe length, we were able to reduce CO by 37% and HC and NOx by 62%, satisfying the world's most demanding regulatory values with sufficient margin.
The results of this study have been applied to mass-produce low-emissions-technology in 3 kVA generators complying with the severest emissions regulations.