EXPLANATION
The net heat of combustion is a factor in the performance of all aviation fuels. For high performance weight-limited aircraft, the net heat of combustion per unit mass and the mass of fuel loaded determine the total safe range. The proper operation of the aircraft engine also requires a certain minimum net energy of combustion per unit volume of fuel delivered.
This test method is intended for use as a guide in cases where an experimental determination of heat of combustion is not available and cannot be made conveniently, and in which an estimate is considered satisfactory. It is not intended as a substitute for experimental measurements of heat of combustion which can be done by Test Methods ASTM D240 and ASTM D4809. This test method calculates the net heat of combustion from the fuel density, sulfur, and hydrogen content. This calculation is justifiable only when the fuel belongs to a well-defined class for which a relationship between these quantities has been derived from accurate experimental measurements on representative samples of that class. Even in this class, the possibility that the estimates can be in error by large amounts for individual fuels should be recognized.
TEST SUMMARY
The hydrogen content, density, and sulfur content of the sample are determined by experimental test methods and the net heat of combustion is calculated using the values obtained by these test methods based on reported correlations. The following test methods may be used for the actual analyses:
TEST PRECISION
Repeatability: 0.05 MJ/kg
Reproducibility: 0.06 MJ/kg
Bias is not known.