Energy requirement assessment on an electrically heated catalyst with heat-storing material of a small four-stroke engine during cold start

摘要

An electrically heated catalyst (EHC) with heat-storing material of a four-stroke motorcycle engine operating from cold-start conditions was studied to investigate the effect of input energy on the conversion characteristics of the catalyst from cold start. The parameters investigated were the length of the heat-storing material, the heating temperature, the CO setting level, and the heating position. The heating temperatures were 100, 140, 180, and 220℃ and the CO setting levels were 1.3 and 1.8 per cent. The heating positions were at the inlet and mid-section of the catalyst. The heat-storing material was made of stainless steel and was 15 mm wide and 0.3 mm thick. The two lengths tested were 30 and 60 cm. The experimental results showed that good conversion efficiency was attained, even with a low heating energy, using the shorter heat-storing material coupled with a high CO setting. In contrast, good conversion efficiency was not attained with a low heating energy using the longer heat-storing material. Furthermore, heating at the inlet of the catalyst resulted in better CO conversion efficiency with the combination of shorter heat-storing material and higher CO setting. A good CO conversion was also obtained when heating at the mid-section of the catalyst with the combination of longer heat-storing material and higher CO setting. Analysis of the CO converted mass per unit total input energy showed that a peak value generally occurred at a heating temperature of either 140 or 180℃.