Traditional coolants include water, brine, ethylene glycol or propylene glycol solutions, dichloromethane, and trichloroethylene.

Water: Water is stable, safe, non-toxic, non-corrosive, and offers good flow and heat transfer properties. It is inexpensive and readily available. Its main disadvantage is its freezing point of 0°C, which is relatively high. Due to this limitation, water is only suitable for high-temperature cooling applications where the operating temperature is above 0°C. It is the most appropriate coolant for artificial cooling equipment and air conditioning systems operating above 0°C, such as in air handling units. Industrial circulating cooling water typically operates within a temperature range of 10°C to 30°C.

Brine: Brine refers to aqueous solutions of calcium chloride or sodium chloride. It can be used in ice-making machines, indirect cooling refrigeration units, and for cooling packaged food products. The freezing temperature of brine varies with concentration. For calcium chloride brine, the freezing point reaches -55°C at a concentration of 29.9%; for sodium chloride brine, the freezing point reaches -21.2°C at a concentration of 22.4%. In practice, the concentration is selected based on the rule that the freezing point of the solution should be approximately 5°C lower than the evaporation temperature of the refrigeration system. While calcium chloride and sodium chloride are low in cost, they are highly corrosive to equipment.

Propylene Glycol and Ethylene Glycol: These are stable and miscible with water. The freezing point of their aqueous solutions varies with concentration and they are typically used as coolants within an operating temperature range of 0°C to 20°C. Although the freezing point of ethylene glycol or propylene glycol solutions can be as low as -50°C, their viscosity increases rapidly at low temperatures. Therefore, their practical industrial application is generally limited to temperatures above -20°C. Besides, their aqueous solutions also exhibit corrosive properties.

Dichloromethane and Trichloroethylene: These are used in liquid form as coolants. Dichloromethane has a freezing point of -97°C, which is suitable for applications ranging from -50°C to -90°C. However, both dichloromethane and trichloroethylene share the following significant drawbacks: they have high volatility and low boiling points, resulting in substantial losses and requiring frequent replenishment; they contain chlorine, which is highly reactive and can easily detach to form hydrochloric acid or chlorides, leading to equipment corrosion; they have low water solubility, which can cause ice plugging and pipe bursts in low-temperature systems; and they have low heat transfer coefficients.

Suzhou UOLEN New Material Technology Co., Ltd. offers the UOLEN series of synthetic coolants. These next-generation products feature excellent heat transfer performance. They are not only colorless and odorless, but energy-efficient and environmentally friendly. They do not corrode metal equipment including copper, iron, aluminum, and carbon steel as well. They can serve as a direct replacement for the four types of traditional coolants described above, enabling customers to overcome the limitations of conventional products while benefiting from superior performance.