The performance and emissions behaviors of methanol heavy-duty vehicle under cold start and hot start of the WHTC standard condition

Abstract

Methanol is a low-carbon, clean and renewable energy source for partially replacing traditional fossil fuels. In this paper, the emission characteristics of a methanol heavy-duty vehicle are examined under the cold start and hot start of World Harmonized Transient Cycle (WHTC). The experimental results indicate that HC conversion efficiency is achieved 93.41 % under cold start cycle with using three-way catalyst (TWC), while its conversion efficiency is achieved 95.84 % under hot start cycle. Additionally, TWC has a significant impact on CO conversion efficiency, with a reduction of 93.74 % during cold start and an impressive 98.07 % during hot start. Furthermore, the TWC takes longer to reach optimal operating temperature during cold start, leading to a lower NOx emissions conversion efficiency of 79.48 % compared to 88.55 % during hot start. The weighted brake specific HC, CO, and NOx emissions of the methanol heavy duty vehicle are 16.08 mg/kW·h, 45.89 mg/kW·h, and 24.99 mg/kW·h, respectively. These brake specific emissions are lower than China VI emission standard with using TWC. These findings demonstrate the high feasibility of methanol as a promising alternative fuel in transportation section, and highlight the significant role of the TWC in optimizing emission performance of a methanol vehicle.