Study of the SI engine using natural gas for driving a small generator

Abstract

Considering the difficulty in meeting the ever increasing demand of energy as well as greater concern regarding the environment, searches for possible alternative energy resources are being carried out throughout the developed world as well as in many developing countries. Conventional fossil fuel run internal combustion engines are one of the large sources of environmental pollution. Natural gas is one of the most potential alternative fuels that can be used in petrol or diesel run engines of different types, with different degree of engine modifications. Small scale petrol engine run generators are widely used to cope up with frequent power failures in Bangladesh. This research concerns the use of domestic line supply of natural gas as an alternative fuel in a small spark ignition engine run portable electric generator of 1.5kW rated capacity. To retain instant inter-chanagability to petrol fuel and minimum alteration cost, the engine modifications were intended to be kept as minimum as possible. Such an engine could have potential applications in - households, community halls and small commercial units. Smooth engine operation with natural gas was achieved with small alterations to the air intake structure. The engine run with natural gas showed improved performance regarding - fuel economy, overall efficiency and significantly better exhaust emission characteristics, compared to the petrol counterpart. On the other hand the maximum load carrying capacity was found to be limited to some extent (about 85% of rated) and the gas now controlling requirement introduced some added complexity. A simple and cheap. single step gas flow regulating device was designed for running the engine near the rated capacity. This provided smooth engine operations from 50-85% of the rated capacity. Taking the economical and environmental benefits into account natural gas could be a very potential alternative fuel for small scale power generation using Sl engines.