Evidence of the illegitimacy of the additive approach to the determination of the thermophysical properties of coal‐water fuel with glycerol

Summary For the fuel ignition, the thermal conductivity and heat capacity are the key properties that determine the pre‐ignition behavior of the drop of the fuel. The classic monophase fuels, such as natural gas, liquid propellants, or solid one‐component fuels, have been investigated for a long tim...

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Bibliographic Details
Published in:International journal of energy research 2020-11, Vol.44 (14), p.12056-12065
Main Authors: Pinchuk, V.A., Moumane, M., Sharabura, T.A., Kuzmin, A.V., Pinchuk, S.A.
Format: Article
Language:English
Subjects:
Additives
Burning
Capacity
Coal
coal‐water fuel
experimental research
Fuels
Glycerol
Heat
heat capacity
Heat conductivity
Heat transfer
Ignition
law of additivity
Liquid propellants
Mathematical analysis
Natural gas
Properties
Properties (attributes)
Slurries
Specific heat
Temperature
Thermal conductivity
Thermophysical properties
Water
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Summary:Summary For the fuel ignition, the thermal conductivity and heat capacity are the key properties that determine the pre‐ignition behavior of the drop of the fuel. The classic monophase fuels, such as natural gas, liquid propellants, or solid one‐component fuels, have been investigated for a long time; and their thermophysical properties are well known in most of the cases. Composite fuels, which have recently attracted the attention of the researchers, have complex contents. In many cases, composite fuel is a mixture of solid and liquid components in the form of a slurry. Coal‐water fuel and its derivatives with different additives are examples of such type fuels. For those fuels, the thermophysical properties are usually unknown. Nowadays, researchers use simple additivity theory for the calculation of the thermophysical properties of complex fuels for the first approach. Authors of this research believe that the simple additivity approach is not correct and can lead to the wrong results in the case of the numerical research of the ignition and burning processes of such a fuel. In the present research, the thermophysical properties of coal‐water fuel with glycerol additives were experimentally obtained. It was found that the coefficient of thermal conductivity increases with temperature and varies in the range of 0.45 to 0.53 W/(m·K). The heat capacity of the fuel also increases with the temperature and varies from 4.7 to 5.5 kJ/kg·K. The higher the glycerol content, the lower the thermal conductivity and heat capacity of the composite fuel in the investigated temperature range. The results confirm the failure of the approach of the additivity law usage. Neither, thermal conductivity coefficient or heat capacity of the coal‐water fuel with the addition of up to 20% glycerol complies with the additivity law. Differences between real values of the thermophysical properties and calculated ones are more than 30% to 50%. Empirical expressions for calculation of the thermophysical properties of coal‐water fuel with the addition of up to 20% glycerol are presented. Glycerol affects thermophysical properties of the resulting suspension; thermophysical properties of CWF with glycerol do not obey law of additivity changes in thermophysical properties and can eliminate improvements in CWF combustion.
ISSN:0363-907X
1099-114X
DOI:10.1002/er.5858