Development of an all Speed Governed Diesel-CNG Dual Fuel Engine for Farm Applications

This paper discusses the development of an all speed governed diesel-natural gas dual fuel engine for agricultural farm tractor. A 45 hp, 2.9 liters diesel-natural gas dual fuel engine with a novel closed loop secondary fuel injection system was developed. A frugal approach without any modification of the base mechanical diesel fuel injection system was followed. This approach helped to minimize the cost impact, while meeting performance and emissions at par with neat diesel operation. Additional cost on gas injection system is redeemed by cost savings on diesel fuel. The dual fuel technology developed by Mahindra & Mahindra Ltd., substitutes on an average approximately 40% of diesel with compressed natural gas, meeting the TREM III A emission norms for dual fuel while meeting all application requirements. The governing performance of the tractor was found to be superior than base diesel tractor. A prototype dual fuel tractor was tested for all field applications including puddling, cultivator, rotavator, plough and haulage to confirm application suitability and substitution performance. The raw emission results showed an increase in unburned hydrocarbon and carbon monoxide emissions, while nitrous oxide emissions decreased marginally. A diesel oxidation catalyst was used to reduce the carbon monoxide and hydrocarbon emissions and exhaust gas recirculation was used to reduce the nitrous oxides. Overall emissions in dual fuel were achieved below the diesel emissions with 40% particulate matter reduction.