CALCULATION OF HEATING VALUE OF ORGANIC SUBSTANCES USING OXYGEN CONSUMPTION

At present over 90% of world energy is thermal energy. Thus the question is how to determine the energy potential of various fuels and combustible substances. The experimental measurement of thermal energy is carried out by burning of dehydrated samples in a special device - bomb calorimeter filled with oxygen under pressure. The bomb calorimeter is a complex, expensive and not always available device. In addition, the measurement of heating value is lengthy and requires multiple repetitions to obtain a reliable result. Therefore, numerous studies were performed to develop express methods for calculating the heating values of various combustible organic fuels, substances and materials. In this paper a relationship between net heating value (q) and oxygen consumption (NO2) has been studied for various types of fuels, organic low-molecular compounds, synthetic polymers and biopolymers. The linear dependence q=f (NO2) was confirmed, which can be described by the equation: q = Eq NO2, where average energetic parameter of oxygen is Eq = 418 13 kJ/mole O2. This equation provides a calculation of the net heating values of various substances with an average relative deviation (ARD) of 6%. To reduce the deviation of calculated values from experimental heating values a variable energetic parameter, Eq,v, in the range of 406 to 430 kJ/mole O2 for similar types of substances was found. However, in the cases where it is difficult to determine the type of combustible substance, the use of variable parameter, Eq,v, is not possible. As a result of further research a quite precise equation with a constant value of the general energetic parameter of oxygen Eo= 412.8 kJ/mol O2 was derived, which is suitable for calculating the net heating values of various types of organic substances with ARD of 1%: qc,o = Eo NO2,c, where corrected oxygen consumption NO2,c = c + 0.81 s + 0.24 h – 0.43 o; and c, s, h, o are numbers of the corresponding atoms in molecule of low-molecular compound or in repeat link of polymer.