Specification :

The major end uses of ethylene glycol are as an antifreeze, which accounts for over 50% of ethylene glycol' s commercial uses, and as raw material in the production of polyester fibers, mainly PET, which accounts for 40% of total ethylene glycol consumption. Because this material is cheaply available, it finds many niche applications.

Coolant and heat transfer agent
The major use of ethylene glycol is as a medium for convective heat transfer in, for example, automobiles and liquid cooled computers. Ethylene glycol is also commonly used in chilled water air conditioning systems that place either the chiller or air handlers outside, or systems that must cool below the freezing temperature of water. In geothermal heating/ cooling systems, ethylene glycol is the fluid that transports heat through the use of a geothermal heat pump. The ethylene glycol either gains energy from the source ( lake, ocean, water well) or dissipates heat to the source, depending if the system is being used for heating or cooling.

Pure ethylene glycol has a specific heat capacity about one half that of water. So, while providing freeze protection and an increased boiling point, ethylene glycol lowers the specific heat capacity of water mixtures relative to pure water. A 50/ 50 mix by mass has a specific heat capacity of about 0.75 BTU/ lb F, thus requiring increased flow rates in same system comparisons with water. Additionally, the increase in boiling point over pure water inhibits nucleate boiling on heat transfer surfaces thus reducing heat transfer efficiency in some cases, such as gasoline engine cylinder walls. Therefore, pure ethylene glycol should not be used as an engine coolant in most cases.

Antifreeze
Due to its low freezing point and tendency to form glasses, ethylene glycol resists freezing. A mixture of 60% ethylene glycol and 40% water does not freeze until temperatures below â ˆ ’ 45 Â ° C ( â ˆ ’ 49 Â ° F) .[ 3] Diethyleneglycol behaves similarly. It is used as a deicing fluid for windshields and aircraft. The antifreeze capabilities of ethylene glycol have made it an important component of vitrification ( anticrystallization) mixtures for low-temperature preservation of biological tissues and organs.

Ethylene glycol disrupts hydrogen bonding when dissolved in water. Pure ethylene glycol freezes at about â ˆ ’ 12 Â ° C ( 10.4 Â ° F) , but when mixed with water molecules, neither can readily form a solid crystal structure, and therefore the freezing point of the mixture is depressed significantly. The minimum freezing point is observed when the ethylene glycol percent in water is about 70% , as shown below. This is the reason pure ethylene glycol is not used as an antifreezeâ € � water is a necessary component as well.

However, the boiling point for aqueous ethylene glycol increases monotonically with increasing ethylene glycol percentage. Thus, the use of ethylene glycol not only depresses the freezing point, but also elevates the boiling point such that the operating range for the heat transfer fluid is broadened on both ends of the temperature scale. The increase in boiling temperature is due to pure ethylene glycol having a much higher boiling point and lower vapor pressure than pure water; there is no chemical stabilization against boiling of the liquid phase at intermediate compositions, as there is against freezing.

In the plastics industry, ethylene glycol is important precursor to polyester fibers and resins. Polyethylene terephthalate, used to make plastic bottles for soft drinks, is prepared from ethylene glycol.

Hydrate inhibition
Because of its high boiling point and affinity for water, ethylene glycol is a useful desiccant. Ethylene glycol is widely used to inhibit the formation of natural gas clathrates ( hydrates) in long multiphase pipelines that convey natural gas from remote gas fields to an onshore processing facility. Ethylene glycol can be recovered from the natural gas and reused as an inhibitor after purification treatment that removes water and inorganic salts.

Natural gas is dehydrated by ethylene glycol. In this application, ethylene glycol flows down from the top of a tower and meets a rising mixture of water vapor and hydrocarbon gases. Dry gas exits from the top of the tower. The glycol and water are separated, and the glycol recycled. Instead of removing water, ethylene glycol can also be used to depress the temperature at which hydrates are formed. The purity of glycol used for hydrate suppression ( monoethylene glycol) is typically around 80% , whereas the purity of glycol used for dehydration ( triethylene glycol) is typically 95 to more than 99% . Moreover, the injection rate for hydrate suppression is much lower than the circulation rate in a glycol dehydration tower.

Niche applications
Minor uses of ethylene glycol include the manufacture of capacitors, as a chemical intermediate in the manufacture of 1, 4-dioxane, and as an additive to prevent corrosion in liquid cooling systems for personal computers. Ethylene glycol is also used in the manufacture of some vaccines, but it is not itself present in these injections. It is used as a minor ( 1â € “ 2% ) ingredient in shoe polish and also in some inks and dyes. Ethylene glycol has seen some use as a rot and fungal treatment for wood, both as a preventative and a treatment after the fact. It has been used in a few cases to treat partially rotted wooden objects to be displayed in museums. It is one of only a few treatments that are successful in dealing with rot in wooden boats, and is relatively cheap. Ethylene glycol may also be one of the minor ingredients in screen cleaning solutions, along with the main ingredient isopropyl alcohol.

Ethylene glycol is commonly used as a preservative for biological specimens, especially in secondary schools during dissection as a safer alternative to formaldehyde. It can also be used in killing jars. It is also used as part of the water-based fluid used to control subsea oil and gas production equipment.