Why Is Glycol Used In Cooling Systems?

Contenuto Nascondere

1 Why Is Glycol Used In Cooling Systems?

1.1 What is glycol?

1.2 Glycol vs water: Why not use water?

1.3 Why Not Use Pure Glycol?

1.4 Relationship Between Glycol Concentration, Freezing Point, and Viscosity

1.5 LNEYA:Reliable Laser Chiller Manufacturer

1.6 Related chillers

1.7 CONTATTO

Many cooling systems, such as refrigeratori industriali, HVAC, and automotive engine cooling, use a glycol-water mixture as a coolant. What is glycol? Why not just use water as a coolant? What benefits does a glycol-water mixture provide? What are the effects of the concentration of the mixture? This article will tell you everything you need to know about glycol.

What is glycol?

Glycol is a viscous liquid commonly mixed with water and used as antifreeze. Ethylene glycol (EG) and propylene glycol (PG) are commonly used in chillers.

Ethylene glycol is a colorless, odorless, sweet-tasting and toxic liquid. It is miscible with water and acetone. It is often used as a solvent, antifreeze, and a raw material for synthetic polyester.

Propylene glycol is similar to ethylene glycol in appearance and odor, but it is non-toxic. It is widely used as a wetting agent and preservative in cosmetics, toothpaste, soaps, and hair dyes, often combined with glycerol or sorbitol. It is often used instead of ethylene glycol in food and medical cooling systems.

Property	Ethylene Glycol	Propylene Glycol
Chemical Formula	C₂H₆O₂	C₃H₈O₂
Toxicity	Toxic (not food safe)	Low toxicity (food grade safe)
Freeze Point Depression	Stronger	Weaker
Heat Transfer Efficiency	Slightly better	Slightly lower
Viscosity at Low Temp	Lower	Higher
Biodegradability	Lower	Higher
Cost	Lower	Higher
Common Applications	Industrial cooling, antifreeze	Food, pharma, eco-friendly cooling

Glycol vs water: Why not use water?

Water can also be used for cooling and is cheaper than glycol. Why not use water as antifreeze?
This is mainly because glycol is more chemically stable. Water freezes below 0°C and may damage pipes. It evaporates at high temperatures. This limits the operating temperature range of the cooling system. The freezing point of glycol-water mixture is very low, and can reach below -40°C depending on the concentration.

Property	Acqua	Ethylene Glycol	Propylene Glycol
Freezing Point	0°C	-12°C (pure) / -50°C (mixed)	-59°C (pure) / -50°C (mixed)
Boiling Point	100°C	197°C	188°C
Viscosity (25°C)	0.89 mPa·s	16.1 mPa·s	58.1 mPa·s
Specific Heat	4.18 J/g·K	2.38 J/g·K	2.51 J/g·K
Cost	Lowest	Lower	Slightly higher

Why Not Use Pure Glycol?

Glycol is highly viscous and doesn’t flow easily through the cooling system. This can lead to reduced heat transfer and higher pump workload. Mixing with water can significantly reduce the viscosity of glycol, allowing it to flow smoothly in the pipe. Glycol-water mixture does not only contain glycol and water. In order to prevent the solution from corroding the pipe or breeding bacteria, corrosion inhibitors and antibacterial agents are added.

Relationship Between Glycol Concentration, Freezing Point, and Viscosity

The concentration of glycol affects the freezing point and viscosity of the solution. The higher the concentration, the lower the freezing point, but the viscosity will also increase, and the fluidity will deteriorate, which will affect the heat exchange efficiency.

Concentration (Vol%)	EG Freezing Point (°C)	PG Freezing Point (°C)	EG Viscosity (mPa·s @25°C)	PG Viscosity (mPa·s @25°C)
0% (Pure Water)	0°C	0°C	0.89	0.89
20%	-8°C	-7°C	1.5	2.1
40%	-24°C	-22°C	3.3	5.5
50%	-36°C	-32°C	5.0	9.5
60%	-48°C	-45°C	8.2	15.0

Note:
• EG = Ethylene Glycol
• PG = Propylene Glycol
• The data are approximate and may vary slightly depending on temperature and brand.

The freezing point of ethylene glycol and propylene glycol will begin to rise after the concentration exceeds about 65%, so it is not recommended to use too high a concentration.

LNEYA:Reliable Laser Chiller Manufacturer

If you are looking for an economical chiller that can operate stably at low temperatures, a glycol chiller might be a suitable solution.Want to know if glycol chiller is suitable for your application? Welcome to contact LNEYA chiller experts to provide you with coolant configuration recommendations and temperature control technical support.