A = aromatics, volume %
G = gravity, API (American Petroleum Institute)
V = volatility: boiling point or average of Test Method D 86 10%, 50%, and 90% points, C.
To correct for the effect of the sulfur content of the fuel on the net heat of combustion, apply the following
equation:
Q = Qp x [1-0.01(S1)] + C(S1) (3)
Where:
Q = net heat of combustion, megajoules/kilogram or British thermal unit (BTU) per pound, of the fuel
containing S1 weight percent sulfur,
Qp = Qp1 (inch-pound units) or Qp2 (SI units),
S1 = sulfur content of the fuel, mass %, and
C = 0.10166 (SI units) or 43.7 (inch-pound units) = a constant based on the thermochemical data on
sulfur compounds.
The empirical equations for the estimated net heat of combustion, sulfur-free basis, were derived by stepwise
linear regression methods using data from 241 fuels, most of which conform to specifications for aviation
gasolines and aircraft turbine or jet engine fuels.
Calculation and reporting procedures.
Calculate the net heat of combustion, sulfur-free basis, using equation No. 1. Round the value obtained to
the nearest one-thousandth.
Example:
Sample: Kerosene
Determined Values:
Aromatics, A= 12.5% volume
3
Density, D = 805.0 kg/m
Distillation
T10 = 203C
T50 = 233C
T90 = 245C
T= (203 + 233 + 245) / 3 = 227C
(4)
Calculated Value: A x T = 2837.5
(5)
Substitute into equation No. 2.
Qp2 = [5528.73 - 92.6499A = 10.1601(227)+ 0.314169 (2837.5)] / D + 0.0791707 (12.5) (2) -
0.00944893(227) - 0.000292178 (2837.5) + 35.9936
Therefore:
Qp2 = 43.4101015 = 43.410 MJ/kg, sulfur-free basis
Report the result to the nearest one-thousandth as net heat of combustion of the fuel in megajoules per
kilogram.
1-8
QM 5181
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