jmw
Industrial
- Jun 27, 2001
- 7,435
SAE J1349 and SAE J1995 describe the determination of net and gross power of engines. These calculations involve fuel density and viscosity.
Most fuels are blended for some measure of their energy, whether it is octane rating, cetane rating, specific energy or even ignition index. Density and viscosity come a long way down the list. Aviation fuel, for example, when it is bridged into the airports from the refineries, is segregated to keep different batches with differtent densities apart. One reason why density measurement can be used to segregate disel and "green" or low sulphur diesel into storage as it is delvered through a common pipeline from the refienery to the terminal is due to the marked variation in density between production bathes.
My question has more to do with how engine design or performance is influenced by variations in the density, or more probably the viscosity of the fuel. For large diesel engines burning residual fuels the fuel is heated to maintain a constant viscosity as this affects the spray pattern and droplet size as it is injected into the cylinders. I was tempted to think that viscosity was not critical to marine distillates far less to commercial diesel or even petrol but i begin to wonder if that isn't a simplistic deduction based on the fact that nobody does anything about compensation for these factors. This may be because they haven't been able to do anything till now but just how significant are these effects? anybody know?
Most fuels are blended for some measure of their energy, whether it is octane rating, cetane rating, specific energy or even ignition index. Density and viscosity come a long way down the list. Aviation fuel, for example, when it is bridged into the airports from the refineries, is segregated to keep different batches with differtent densities apart. One reason why density measurement can be used to segregate disel and "green" or low sulphur diesel into storage as it is delvered through a common pipeline from the refienery to the terminal is due to the marked variation in density between production bathes.
My question has more to do with how engine design or performance is influenced by variations in the density, or more probably the viscosity of the fuel. For large diesel engines burning residual fuels the fuel is heated to maintain a constant viscosity as this affects the spray pattern and droplet size as it is injected into the cylinders. I was tempted to think that viscosity was not critical to marine distillates far less to commercial diesel or even petrol but i begin to wonder if that isn't a simplistic deduction based on the fact that nobody does anything about compensation for these factors. This may be because they haven't been able to do anything till now but just how significant are these effects? anybody know?
