ETHYL ALCOHOL BASED SECONDARY FLUID - EFFECT OF CORROSION INHIBITORS ON THERMOPHYSICAL PROPERTIES

摘要

Currently available commercial ethyl alcohol (EA) based secondary fluids in Sweden and other Nordic countries contain up to 10 wt-% denaturing agents (in concentrate alcohol) in form of propyl alcohol and n-butyl alcohol but no corrosion inhibitors. These studies were initiated due to a growing need for providing any protection against corrosion and extending the lifetime of the system. A literature search has been made to find the compatible corrosion inhibitors that can effectively protect the system. Afterwards, measurements have been performed to investigate the effect of these corrosion inhibitors on the thermophysical properties of the base fluid. Results showed that the different corrosion inhibitors can affect the thermophysical properties even when added in small concentrations. The presences of corrosion inhibitor had a positive effect and decrease the freezing point. Additionally, the presence of corrosion inhibitor in 30 wt-% ethyl alcohol samples had no significant effect on the dynamic viscosity and only EA25 + 0.01 SG (sodium gluconate) sample showed lower dynamic viscosity value by up to 10%. The corrosion inhibitors had negative effect on the thermal conductivity in the full temperature range. EA25 and EA30 samples containing sodium gluconate, benzotriazole and sodium molybdate had higher specific heat capacity than the pure solutions. This study showed that both benzotriazole and 2-mercaptobenzothiazole seem to be the most promising corrosion inhibitor for ethyl alcohol based secondary fluids.