Abstract
Diesel fuel which has been used for buses in Ho Chi Minh city (HCMC) is one of the causes of recent severe air pollution. Compressed Natural Gas (CNG) which has been exploited in Vietnam is a clean fuel and has a potential use for vehicles, especially for buses in such big cities as HCMC. This paper presents results from initial study on planning/developing mass transit buses fuelled with CNG in HCMC. The optimization of conversion of current 819 TRANSINCO B80 diesel buses, which are powered by D6AV diesel engines, was conducted. The piston of this engine was modified to achieve compression ratio of 12:1, the cylinder head was modified to install spark plug and a group of five Type 2 tanks was installed forwardly on the roof of the bus to make CNG storage system. The design of new CNG bus based on imported DHZ6110RCD chassis, powered by OM6NG1-24 single point injection CNG engine, was also analyzed and performed. Comparison in initial, fuel, and environmental costs was made between the diesel bus fleet and CNG bus fleet consisting of 19819 units. The results show high benefits of environmental as well as fuel costs and a short payback period for the CNG bus system, revealing a prospect of CNG utilization for buses in HCMC in near future.
Keywords: CNG fuel, environmental pollution, bus design.