Chemistry of MEG

MEG is an odorless and colorless liquid. MEG is miscible with water, alcohols, and many other organic compounds without any requirement of special emulsifiers or any other compounds. Monoethylene Glycol is an organic compound that contains two hydroxyl groups (OH). MEG has high thermal stability due to its strong O-H bonds. The structural formula of MEG is illustrated below:

Structural formula of Monoethylene Glycol (MEG)

Properties of MEG

Some required properties of antifreeze products are listed below:

  • Having low viscosity and low effect on viscosity of base coolant liquid
  • High thermal resistivity and heat transfer capacity
  • High miscibility with water without needing any emulsifier or intermediary chemicals
  • Being compatible with different types of water (such as hard water)
  • Prevention of sediment formation in coolants
  • Compatibility with elastomers which are used in machines
  • Neutral to other chemicals such as corrosion control agents and scale inhibitors
  • Anti-corrosive specifications

Introduction for Antifreeze agents and Coolants

In many industrial applications, antifreeze agents are added to the water or other liquids for various reasons, such as reducing the freezing point and increasing the boiling point of the liquids which are used in the cooling systems. In these cooling systems, liquids known as coolants, are used in circulating systems to transfer the heat generated by machines and engines. Coolants are widely used in many power plants, geothermal plants, production facilities, petrochemical industries in order to control and transfer excessive heat which in-turn maintains the temperature of engines in the planned range.

Difference between Coolant and Antifreeze agent

Antifreeze agents are one of the ingredients of coolants. Antifreeze agents are an undeniable part of coolants due to their benefits such as preventing the circulating liquid from freezing. Along with scale inhibitors and corrosion control additives, antifreeze agents are added to the coolants such as water. The coolants have high thermal resistance in low to high temperatures ranging between 0˚ C to 100˚ C degrees. Although most of the coolants and antifreeze share similar specifications and properties, antifreeze chemicals mostly acquire higher stability against cold environments.

Common Coolant and Antifreeze agents

Antifreeze materials are usually a thick liquid which is normally diluted with water to make a perfect coolant liquid. Some of the most common antifreeze products which are widely utilized in numerous industries are calcium chloride, methanol, Monoethylene Glycol (MEG) and ethanol. In addition, among all types of antifreeze agents, MEG is the preferable chemical. The turbulence in freezing and boiling point of liquids is highly dependent on the type, purity and concentration of antifreeze agents which are added. For example, mixing water with 50% vol/vol pure Monoethylene Glycol can reduce the water freezing point from 0˚ C degrees to minus 36˚ C degrees.

On the other hand, water is the most used coolant due to its availability, high heat transfer coefficient, high boiling point, and low cost. Mixtures of water & MEG, and water & Propylene Glycol are other common coolants.