Why Glycol Is Used for Cooling?
The most commonly used coolant in a chiller is water or a mixture of water and another substance with appropriate heat conduction properties – such as a glycol compound. Glycol-based coolants consist of either ethylene glycol or propylene glycol. The main advantage of glycol coolants is anti-freeze properties.
Pure water freezes at 0 degrees C, while 30% ethylene glycol freezes at -14 degrees C. The low freezing point of glycol mixtures makes them ideal for cooling items that are below the freezing point of water.
Although glycol has a lower heat capacity than water (each kilogram of glycol is easier to heat than one kilogram of water), the larger temperature difference allows the glycol mixture to remove heat more quickly than pure water. The glycol mixtures are more suitable for applications where the chiller must quickly remove large amounts of heat.
In addition to providing excellent heat transfer parameters, glycol tends to discourage algae growth in heat transfer equipment.
How Does A Glycol System Work?
A chiller is a machine that removes heat from a liquid. This liquid can then be circulated through a heat exchanger（or a cooling jacket） to cool the equipment, another process stream, or just to be used. At the heart of a glycol system is the glycol chiller.
Glycol chiller, as the name implies, uses glycol as the chiller’s cooling medium. A glycol chiller consists of a compressor, an evaporator, a condenser, a throttling element, and an electric control system.
Let’s see what’s the working principle of a glycol chiller:
The chiller’s refrigerant absorbs thermal energy from your process, usually the refrigerant will be turned into gas. The gaseous refrigerant is then circulated to a condenser which expels the heat through evaporative condensation. This heat exchange condenses the refrigerant back into a cooler gas& liquid mixture that is sent back to the process heating source to begin the cycle again.
Ratio of Water to Glycol to Use
Calculating the proper ratio of glycol to water in a refrigeration system depends on the coldest temperature you need during operation. If the refrigeration system is used indoors, where there is a lower chance of freezing, the amount of glycol required will be significantly less than a glycol chiller used outdoors. it is very important to use the correct ratio of glycol to water in the chiller system. Adding too much glycol to a chiller system will result in an inefficient system. However, insufficient glycol can cause the system to freeze, possibly bursting pipes and even destroying the chiller evaporator.
Check the most used glycol ratio chart:
What Can A Glycol Chiller Be Used For?
Glycol chillers are most used for chemical processing, pharmaceutical formulation, food and beverage processing.
Glycol Chiller Applications
How Glycol Chillers are Being Used
Cooling the Wort
Crash Cooling Vessels
Cold Chilling the Juice
Cold Storage of the Final Product
Circulation Between Distillation Tanks & Stills
In breweries, using a glycol chiller allows producers to lower the temperature of the product dramatically over a short period of time, depending on the production needs.
For cooling in brewing, there are several processes in which it is important to lower or maintain the temperature – such as cooling the beer sharply after fermentation, or maintaining a steady temperature during fermentation (which generates heat), or cooling the wort after the initial boiling process.
Winery chillers are used in the fermentation process of winemaking to control the temperature during fermentation. The temperature of the glycol solution varies depending on the type of wine being made and each winemaker’s preference, but most winery chillers operate in the 2 Deg C to 10 Deg C range (7 Deg C to 15 Deg C for wine containers).
A glycol chiller takes advantage of this fact by chilling liquid glycol solution to well below the freezing point of water while pumping it through mats that are below the ice rink surface. These mats are then sprayed with water causing the water to freeze around and above the mats.
A properly designed dairy glycol chiller can cool the milk very rapidly to help keep milk temperatures (and bacteria growth) under control as it is transferred from the milking parlor to his insulated tank.
In addition to the above items, glycol chillers can be widely used in rubber, plastic, petroleum, chemical, electronics, paper, textile, brewing, pharmaceutical electroplating, central air conditioning and many other fields.
How To Choose The Right Capacity Of A Glycol Chiller?
For the above information, we will know the important role played by glycol chillers is not only in industry but also in commercial applications.
There are some useful tips for sizing your glycol chillers:
1. Air-cooled Or Water-cooled
Air-cooled chillers use a condenser that is similar to the “radiators” in a car. They use a fan to force air through the refrigerant coil. Unless they are specifically designed for high ambient conditions, air-cooled condensers need to operate effectively at an ambient temperature of 35°C (95°F) or less.
Air-cooled chillers require less maintenance than water-cooled chiller units.
Advantages of air-cooled chiller:
- Air-cooled chillers do not require cooling towers.
- Easier to install compared with a water-cooled chiller.
Water-cooled chillers function in the same way as air-cooled chillers but require two steps to complete the transfer of heat. First, heat enters the condenser water from the refrigerant vapor. The warm condenser water is then pumped to the cooling tower, where the heat from the process is eventually vented to the atmosphere.
Advantages of water-cooled chiller:
- Higher COP(Coefficient Of Performance).
- Lower cost on power for the same cooling capacity.
- Have a longer lifespan.
- Relatively quieter than air-cooled chillers.
- Provide more consistent cooling performance.
2. Cooling capacity
How to calculate the cooling capacity I need?
Let’s see the below formula.
- Calculate Temperature Differential = Incoming Water Temperature (°c) – Outlet Chilled Water Temperature(°c)
- Water flow rate that you need per hour(m³/hour)
- Get in tons of cooling capacity = Water Flow Rate x Temperature Differential ÷ 0.86 ÷ 3.517
- Oversize the chiller by 20% Ideal Size in Tons = Tons x 1.2
- You have the ideal size for your needs.
Fill out our quick sizing form and we will be able to provide you with the glycol chiller selection customized to your process.
If you are not sure how to choose the cooling capacity, please contact us.
3. Whether A Built-in Tank Is Necessary
In a chiller system, a tank is usually equipped to buffer the thermal load of the chiller.
But should we choose a built-in type of tank or an external type of tank?
A chiller with a built-in tank is easier to install and can be used simply by connecting a water pipe to your application. But it has a limited capacity and is not suitable for applications with larger chilled water demands.
External tank’s capacity can be customized according to specific needs. It can buffer a larger heat load, store more chilled water, but the installation will be more troublesome.
4. Water Flow
The water flow of a glycol chiller is mainly controlled by the pump, so you can choose a pump with different flow rates according to your specific needs.
Check some of our glycol chiller models: