In addition to the temperature properties listed in Table 4.4: Fuel species single-temperature properties, the Fuel Library contains a number of temperature-dependent properties for the liquid-fuel components. These properties are provided using correlations to temperature and coefficients that correspond to those correlations. In this section, the nature of the input for each temperature-dependent property is described. The correlations and coefficients used in the Reaction Workbench fuel-property file originate from the DIPPR Database [40]. The reference temperature for these values is 298 K.
For the fuel species listed in Table 4.3: Chemical species identification properties, the coefficients are included in the fuelproperty file within the Installation data directory.
Liquid Density is a 3-coefficient correlation with units of kmole/m3. This property is tabulated against temperature and used in the vaporization model for liquid fuels. The correlation with temperature for Liquid Density is:
 | (4–1) |
where the values for the 3 coefficients 
, 
, and 
are given in a fuel’s LiquidDensity property tag,
while 
is the Critical Temperature, and is included in the
CriticalTemperature tag.
Vapor Pressure is a 5-coefficient correlation with units of Pa. This property is tabulated
against temperature and used in the Vaporization model for liquid fuels. The correlation for
VaporPressure is:
 | (4–2) |
where the values for the 5 coefficients 
through 
are given in a fuel’s VaporPressure property
tag.
Liquid Heat Capacity or Liquid Specific Heat is tagged
LiquidSpecificHeat. This property is tabulated against temperature and
used in the vaporization model of liquid fuels. It is a 5-coefficient correlation with units of
J/kmol-K.
The first number in the tag is an integer indicating the type of the correlation and the
next five numbers are the five correlation coefficients: 
through 
. The liquid specific heat calculation uses two types of correlations
(mutually exclusive). The type of correlation is determined based on the first ID tag that is
either 1 or 2. The Type 1 correlation
(Equation 4–3) is
most commonly used. However, a few components, such as n-butane and
n-heptane, use the Type 2 correlation
(Equation 4–4).
 | (4–3) |
 | (4–4) |
In Equation 4–4, 
is a reduced temperature, 
.
Liquid Viscosity is tagged LiquidViscosity. This property is
tabulated against temperature and used in the vaporization model of liquid fuels. It is a
7-coefficient correlation with units of Pa-sec. The correlation is
 | (4–5) |
where the first 5 numbers in a fuel’s LiquidViscosity property
tag are values for the 5 coefficients 
through 
and the 6th and 7th numbers are lower and upper temperature bounds for the
correlation.
Surface Tension is tagged SurfaceTension. The property is tabulated
against temperature or reduced temperature and used in the vaporization model of liquid fuels.
It is a 5-coefficient correlation with units of N/m. The first number in the tag is an integer
indicating the type of the correlation and the next five numbers are the five correlation
coefficients to ( and are usually 0).
The surface tension calculation uses two types of correlations (mutually exclusive). The type of correlation is determined based on the first ID tag of either 1 or 2. The Type 1 correlation (Equation 4–6) is most commonly used. However, a few components, such as methanol and ethanol, use the Type 2 correlation (Equation 4–7).
 | (4–6) |
where temperature is 
or a reduced temperature, 
.
 | (4–7) |
Liquid Thermal Conductivity is tagged LiquidThermalConductivity. This
property is tabulated against temperature and used in the vaporization model of liquid fuels.
It is a 5-coefficient correlation with units of J/m-sec-K. The correlation is
 | (4–8) |
where the values for the 5 coefficients 
through 
are given in a fuel’s LiquidThermalConductivity
property tag.
Heat of Vaporization is tagged HeatVaporization. This property is
tabulated against temperature and used in the vaporization model of liquid fuels. It is a
5-coefficient correlation with units of J/mole. The correlation is
 | (4–9) |
where the values for the 5 coefficients 
through 
are given in a fuel’s HeatVaporization property
tag.
Values under the property tag BlendONCNParameters are used in a
nonlinear blending technique to estimate Octane Numbers and Cetane Numbers, as shown in Equation 4–10 and Equation 4–12. This method was adapted to provide the best fit for a pure
component-based expression, rather than a lumped component-class expression, such as seen in
Ghosh et al. [41] [42] In addition, the paraffin adjustment term
was modified to include a contribution from aromatics as shown in Equation 4–11.
 | (4–10) |
Table 4.5: Definitions of symbols used in Equation 4–10
|
P |
n- and iso-paraffins |
|
O |
Olefins |
|
N |
Naphthenes |
|
A |
Aromatics |
|
ONi |
ON of component i |
|
Bi |
Correlation parameter for component i |
|
vi |
Liquid volume fraction of component i |
 | (4–11) |
This correlation is used for both RON and MON, but the coefficients
are different. Note that 
is calculated only for paraffins and its value is non-zero when naphthenes
(for example, MCH or decalin), olefins and/or aromatics are present in the blend.
The correlation for estimating the cetane number is slightly simpler than that for ON as
it does not involve the extra term 
.
 | (4–12) |