COMPARISON OF THEORETICALLY DETERMINED FUEL ECONOMIC INDICES OF TRACTOR DIESEL AND CNG (ALTERNATIVE FUEL) ENGINES

Abstract

The fuel economic indices of tractor diesel and tractor compressed natural gas (CNG) engines were compared theoretically to determine the economy of using the two fuels (i.e diesel and compressed natural gas, (CNG) to power tractor engines under various operating conditions and to determine which of the two tractor fuel engines specified is the most economical. The operating conditions considered are engine rated condition, idle running condition and under maximum torque. The economic indices considered were indicated fuel consumption (g/kwhr), the effective fuel consumption (g/kwhr), the effective indicated efficiency and the hourly fuel consumption (kg/hr). A 47kw stey tractor diesel was compared with a 41.7kw tractor cng engine since the two are in the same tractor classification. The indicated fuel consumption of the tractor diesel engine was determined to be 282.35g/kwhr, while that of the tractor cng was 224.22g/kwhr. The effective fuel consumption of tractor diesel engine under rated condition, idle running and maximum torque were 392.15g/kwhr, 433.50g/kwhr, 433.50g/kwhr and 461g/kwhr respectively. The corresponding values for the tractor cng engine under the same condition were 263.39g/kwhr, 290.21g/kwhr and 275g/kwhr respectively.  The hourly fuel consumptions for the two engines were also determined under the specified conditions as 18.43kg/hr, 4.61kg/hr, 4.61kg/hr and 18.71kg/hr for tractor diesel engine and 11.00kg/hrs 2.75kg/hr and 11.71kg/hr for tractor cng engine. The effective indicated efficiencies of the two engines were determined to be 21.6%for tractor diesel engine and 27.2% for tractor cng engine. The tractor cng is therefore more economical in terms of fuel consumption compared to the tractor diesel engine.