A direct route to the calculation of heating values of liquid fuels by using their density and viscosity measurements

doi:10.1016/S0196-8904(00)00012-1

Energy Conversion and Management

Volume 41, Issue 15, 1 October 2000, Pages 1609-1614

https://doi.org/10.1016/S0196-8904(00)00012-1 Get rights and content

Abstract

Higher heating values (HHVs) of vegetable oils, alcohols and alkanes were determined experimentally and calculated from their density and viscosity measurements. The HHV (kJ g ⁻¹) of the samples was supposed to be a function of density (d, in g cm⁻³) and viscosity (μ, in mm² s⁻¹). The equations developed for the samples represent the correlation obtained by means of regression analyses. The HHVs calculated by developing new equations using densities showed average differences of 0.04, 2.43 and 0.008% for vegetable oils, alcohols and alkanes, respectively. The correlation coefficients were 0.938, 0.674 and 0.936 for vegetable oils, alcohols and alkanes, respectively.The HHVs calculated by developing new equations using viscosities showed average differences of 0.02, 0.91, 0.05 and 0.004% for vegetable oils, alcohols, alkanes and diesel fuels, respectively. The correlation coefficients were 0.998, 0.979, 0.996 and 0.999 for vegetable oils, alcohols, alkanes and diesel fuels, respectively. The density and the viscosity are characteristic properties of liquid fuels for developing new formulae.

Introduction

In our earlier studies [1], [2], [3], formulae were developed for calculation of the higher heating values (HHVs) of biomass fuels from their proximate and ultimate analysis data. HHVs of 16 biomass samples were determined and calculated from proximate analysis [1]. The HHVs of vegetable oils can be calculated by using their saponification values and iodine values [4]. Various formulae for calculating the heating values of coals from their proximate analyses have also been proposed [5], [6], [7], [8].

The higher heating value (HHV) of a fuel is the quantity of heat evolved when one gram of a compound is burnt to CO₂ and H₂O at the initial temperature and pressure. The increase in HHV results from an increase in the number of carbons and hydrogens in a fuel molecule, as well as an increase in the ratio of these elements relative to oxygen and nitrogen [2]. Examination of the data for a great many compounds has shown that the HHV of an aliphatic hydrocarbon agrees rather closely with that calculated by assuming a certain characteristic contribution from each structural unit [9]. For open chain alkanes, each methylene group, –CH₂– contributes very close to 46.96 kJ g⁻¹. If cyclopropane and cyclobutane evolve more energy per –CH₂– group than an open chain compound, it can only mean that they contain more energy per –CH₂– group. Cyclopropane and cyclobutane are less stable than open chain compounds. The increase in the carbon–carbon double bond, –CC– content results in a decrease in the heat content of a compound [9]. The ratio C:H in an alkane or a vegetable oil decreases with increase in molecular weight.

Instead of the methods based on proximate [1], ultimate [2], [3], and chemical [4] analyses of data and experimental determination requiring special instrumentation, heating values of some fuels can be calculated relatively easily using simple physical tests, such as density and viscosity measurements.

The objective of this study was to develop new formulae for calculating the HHVs of liquid fuels by using density measurements of alkanes, alcohols and vegetable oils and by using viscosity measurements of alkanes, alcohols, diesel fuels and vegetable oils.

Section snippets

Experimental

Some of the vegetable oil samples used in this study were supplied from different Turkish vegetal sources. The alcohols (Merck) and alkanes (Merck) were reagent grade and used as received. Samples of diesel fuel used were obtained from Turkish oil sources.

The HHV of the samples was measured in a bomb calorimeter according to the ASTM D2015 standard method.

Mass densities of all the alkanes, alcohols and vegetable oil samples were measured by means of a pycnometer at 293 K.

Viscosities of the

Results and discussion

Densities (d, in g cm⁻³) and higher heating values (HHVs, in kJ g⁻¹) of vegetable oils, alcohols and alkanes were given in Table 1. The HHVs (kJ g⁻¹) of the samples as a function of density (d, in g cm⁻³) can be calculated from the following expressions.

For vegetable oils $HHV =79.014−43.126d$
For alcohols: $HHV =−220.981+316.050d$
For alkanes: $HHV =55.750−11.051d$

The HHVs calculated by using , , are given in Table 1. The HHVs calculated by using , , showed average differences of 0.04, 2.43 and 0.008%

Conclusions

Instead of the methods based on ultimate, proximate and chemical analyses of data and experimental determination requiring special instrumentation, the higher heating values of some fuels can be calculated relatively easily using simple physical tests, such as density and viscosity measurements. The density and the viscosity are characteristic properties of liquid fuels for developing new formulae.

Mathematical equations have been developed to calculate the higher heating values of various

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View full text

A direct route to the calculation of heating values of liquid fuels by using their density and viscosity measurements

Abstract

Introduction

Section snippets

Experimental

Results and discussion

Conclusions

Estimation of calorific values of fuels from lignocellulosics

Energy Sources

Calculation of higher heating values of biomass fuels

Fuel

Petroleum Science and Teechnol

Fuel properties and calculation of h_gher heating values of vegetable oils

Fuel