Heat transfer fluids are divided into mineral oil and synthetic fluid according to the chemical components.
Synthetic fluid is synthesized through chemical reaction and has specified chemical structure and certain chemical name. Main products of synthetic fluids include alkylbenzene, alkyl biphenyl, benzyl and dibenzyltoluene, mixture of biphenyl and diphenyl ether, hydrogenated terphenyl, alkyl diphenyl ether and silicone oil.
Mineral oil is the proper fraction generated through distillation and refinery of crude oil. Its main component is hydrocarbon mixture including the paraffinic, naphthenic and alkyl aromatic.
Synthetic fluid and mineral oil belong to different organic chemicals. Their molecular structures decide the different properties of two kinds. Following issues occur when mixing two kinds of fluids.
Physical properties of system fluid changes after mixing. And system operating condition and heat transfer will not conform to the design requirements.
When mixing the synthetic fluid with mineral oil, under the condition of high temperature unexpected chemical reaction may occur because of the different chemical structures, causing system operation fluctuation and adversely affecting production.
It is difficult to accurately evaluate the mixed fluid quality changes as the existing testing methods and evaluation standard are unable to monitor changes of the specified chemical component or some particular physical property parameters.
Components of mineral oil are more confounding and can’t be regenerated. Synthetic fluid has the certain chemical structure and consistent physical property, which can be regenerated, increasing fluid quality and extending fluid service life. Comparing to the mineral oil, synthetic fluid has better cost performance. Usually, the synthetic fluid is more expensive than mineral oil. When mixing the synthetic fluid with mineral oil, the system mixed fluid will be impossible to be regenerated, causing economic loss and resource wastes.
In conclusion, the mineral oil and synthetic heat transfer fluid should not be mixed.
