The significance of BSFC numbers for engine design and class īSFC numbers change a lot for different engine designs, and compression ratio and power rating. The use of BSFC numbers as operating values and as a cycle average statistic Thus a diesel engine's efficiency = 1/(BSFC × 0.0119531) and a gasoline engine's efficiency = 1/(BSFC × 0.0122225) Some examples of lower heating values for vehicle fuels are:Ĭertification gasoline = 18,640 BTU/lb (0.01204 kW⋅h/g) Regular gasoline = 18,917 BTU/lb (0.0122222 kW⋅h/g) Diesel fuel = 18,500 BTU/lb (0.0119531 kW⋅h/g) The lower heating value (LHV) is used for internal-combustion-engine-efficiency calculations because the heat at temperatures below 150 ☌ (300 ☏) cannot be put to use. To calculate the actual efficiency of an engine requires the energy density of the fuel being used.ĭifferent fuels have different energy densities defined by the fuel's heating value. The conversion between metric and imperial units is:īSFC = BSFC × 608.277 BSFC = BSFC × 0.001644 The relationship between BSFC numbers and efficiency The conversion factor is as follows:īSFC = BSFC × (3.6 × 10 6) The resulting units of BSFC are grams per joule (g/J)Ĭommonly BSFC is expressed in units of grams per kilowatt-hour (g/(kW⋅h)). The BSFC calculation (in metric units) ī S F C = r P may be readily measured by instrumentation with an engine mounted in a test stand and a load applied to the running engine. The term "brake" here as in " brake horsepower" refers to a historical method of measuring torque (see Prony brake). BSFC allows the fuel efficiency of different engines to be directly compared. It may also be thought of as power- specific fuel consumption, for this reason. In traditional units, it measures fuel consumption in pounds per hour divided by the brake horsepower, lb/(hp⋅h) in SI units, this corresponds to the inverse of the units of specific energy, kg/J = s 2/m 2. It is the rate of fuel consumption divided by the power produced. It is typically used for comparing the efficiency of internal combustion engines with a shaft output. The resulting dimensionless engine map fits the minimum BSFC regions of four dieselengines to within 2.5 percent.Measure of the fuel efficiency of internal combustion enginesīrake-specific fuel consumption ( BSFC) is a measure of the fuel efficiency of any prime mover that burns fuel and produces rotational, or shaft power. This common map highlights observable trendsin engine performance based on the influence of these same parameters being scaled across engines. A commonality between maps was found to occurwhen engine data is scaled by specific dimensional parametersthat target data consistency among the primary operating pointsacross engines. The resulting dimensionless engine map fits the minimum BSFC regions of four dieselengines to within 2.5 percent.ĪB - The goal of this work is to develop easily generalized models of heavy duty truck engine maps that allow for approximatecomparisons of engine performance, thus enabling fuel efficientmatching of engines to a set of corresponding loads and routes.This is achieved by applying dimensional analysis to create auniformly applicable, dimensionless Brake Specific Fuel Consumption (BSFC) map that fits the behavior of a wide range ofdiesel engines. N2 - The goal of this work is to develop easily generalized models of heavy duty truck engine maps that allow for approximatecomparisons of engine performance, thus enabling fuel efficientmatching of engines to a set of corresponding loads and routes.This is achieved by applying dimensional analysis to create auniformly applicable, dimensionless Brake Specific Fuel Consumption (BSFC) map that fits the behavior of a wide range ofdiesel engines. T1 - Diesel engine characterization and performance scaling via brake specific fuel consumption map dimensional analysis
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