A glycol solution is a mixture, typically of water and a glycol chemical such as ethylene glycol or propylene glycol, that serves as a liquid in various systems, including cooling, heating, and dehydration. Key properties of glycol solutions include their ability to lower the freezing point of water, elevate the boiling point, inhibit corrosion, and transfer heat efficiently. Ethylene glycol is a common coolant but is toxic, while propylene glycol is a less toxic alternative often used in food and cosmetic applications. 
Types of Glycol Solutions 

• Propylene Glycol (PG):
  A less toxic alternative to ethylene glycol. It is found in food products, cosmetics, and is used in systems where lower toxicity is a priority, such as food-grade refrigeration.

• Ethylene Glycol (EG):
  Known for its excellent heat transfer properties and effectiveness in lowering freezing points. It is widely used in automotive antifreeze, HVAC systems, and industrial cooling.

Primary Uses

• Antifreeze and Coolant:
  Glycol is added to water to prevent it from freezing and to raise its boiling point in closed-loop systems like car radiators and industrial heating/cooling systems. 

• Heat Transfer:
  Glycol solutions efficiently absorb and transfer heat, making them valuable for maintaining consistent temperatures in cooling and heating applications. 

• Dehydration:
  Glycol solutions are also used in industrial processes for dehydration purposes. 

• Corrosion Inhibition:
  Added corrosion inhibitors protect metal components from corrosion and maintain the integrity of the system. 

Key Properties

• Freeze Point Depression:
  Glycol molecules interfere with the formation of ice crystals, significantly lowering the freezing point of the water mixture. 

• Boiling Point Elevation:
  The presence of glycol also raises the boiling point of the solution, allowing it to operate at higher temperatures without boiling off. 

• Heat Transfer:
  Glycol solutions enhance heat transfer capabilities within systems. 

• Toxicity:
  Ethylene glycol is toxic and requires careful handling, whereas propylene glycol is less toxic and is often preferred for safety reasons.