ASTM D4529 Test Method for Estimation of Net Heat of Combustion of Aviation Fuels
5. Procedure
5.1 Determine the aniline point temperature of the sample to the nearest 0.05°C as described in Test Methods D611.
5.2 Determine the density at 15°C of the sample to the nearest 0.5 kg/m3 as described in Test Method D941, Test Method D1217, Test Method D1298, or Test Method D4052 or Guide D1250.
5.3 Determine the sulfur content of the sample to the nearest 0.02 mass % sulfur as described in Test Method D129, Test Method D1266, Test Method D2622, or Test Method D3120.
6. Calculation
6.1 Calculate the net heat of combustion using either Procedure A or B.
6.1.1 Procedure A (By Equation) - Insert the measured values in (Eq 1) and calculate Qp, the net heat of combustion at constant pressure on a sulfur-free basis (Note 4).
Qp = 22.9596 - 0.0126587 A + 26 640.9 (1/ρ) + 32.622 (A/ρ) - 6.69030 x 10(-5)A(2) - 9 217 760 (1/ρ)(2)
where:
ρ = density at 15°C, kg/m3,
A = aniline point temperature, °C, and
Qp = net heat of combustion on sulfur-free basis, MJ kg(-1).
NOTE 4 - In SI units the heat of combustion has the unit J kg(-1), but for practical purposes a multiple is more convenient. The megajoule per kilogram (MJ kg(-1)) is 10(6) J kg(-1) and is customarily used for the representation of heats of combustion of petroleum fuels, particularly for mixtures such as those covered in this international standard.
6.1.2 Procedure B (See Table 1) - Make a linear interpolation between rows bracketing the density and within columns bracketing the aniline point of the sample. Then make a linear interpolation for the aniline point within the row for the calculated density to obtain Qp.
6.2 Calculate the net heat of combustion, Q'p, corrected for sulfur content in accordance with the following equation:
Q'p = Qp - 0.1163 S
where:
S = sulfur content, mass %.
6.3 Calculate the volumetric net heat of combustion in accordance with the following equation:
qp = Qpρ x 10(-3)
where:
qp = volumetric heat of combustion, MJ L(-1).
