The global demand for industrial process cooling system remains steadily rising. Reliability and minimal downtime are the keys to achieving consistent and profitable industrial and commercial processes. This article will consider the best way to achieve the optimal temperature required for production processes in the metal finishing, medical, brewing, and agricultural industries.

Glycol chiller VS water chiller

1: How does the chiller work?

So, how does the chiller work? The process circulates, but we will start from where the cooling medium is connected to your process equipment.

The coolant in the system absorbs the heat energy in the process, which usually causes a phase change to a gas. The gaseous refrigerant is then circulated to the condenser, which discharges heat through evaporative condensation or cooling towers. This heat exchange condenses the cooling medium into a colder liquid, which is sent back to the process heating source to start the cycle again.

What type of coolant is used in the chiller?

The type of coolant used in the chiller depends on the process requirements and cost considerations. The most popular coolant is water or a mixture of water and another substance with appropriate thermal conductivity (such as a glycol compound).

Water: Using water as a coolant is an economical method because in most cases, water can be easily obtained at the lowest cost. Alternatively, pure water (deionized water, reverse osmosis) can be used in a water-based chiller to achieve higher cooling efficiency.

Glycol: glycol-based coolants consist of ethylene glycol or propylene glycol. Although the two variants have similar physical properties, do not mix them. The main advantage of glycol coolant is to improve corrosion resistance and antifreeze performance.

2: Why use ethylene glycol for cooling

Compared with using ordinary water as the cooling liquid, the use of glycol-water mixture as the cooling liquid has many advantages. These advantages are due to its unique physical properties, including a lower freezing point than water.

Heat transfer between water and glycol

For water without impurities, its freezing point is 0°C, which is much higher than when pure ethylene glycol becomes solid at -13°C. When the mixture of ethylene glycol and water is changed, the freezing point of the coolant will also change. As an example, 10% ethylene glycol will freeze at -3.5°C, while a 60% ethylene glycol solution will freeze at -52°C.

It can be clearly seen from the above analysis that the refrigerant characteristics of ethylene glycol are more suitable for refrigerators that are expected to operate in a low temperature environment. Under these hot conditions, the cooling water can freeze and hinder the circulation of the chiller, while reducing overall efficiency.

In contrast, using a glycol-based chiller will take advantage of its antifreeze properties to ensure that the coolant maintains the desired fluid state.

3: glycol chiller VS water chiller

Both glycol chillers and chillers can be used to satisfactorily dissipate the heat generated during the production process. The fundamental difference between the two types of chillers is the change in their freezing point and thermal conductivity.

The freezing point of pure ethylene glycol or a mixture of ethylene glycol and water is much lower than that of pure water. This means that glycol-based chillers are more suitable for low-temperature environments. On the contrary, compared with glycol mixtures, water has a better ability to retain and conduct heat in related processes. As a result, the heat transfer efficiency for water chillers will be higher than glycol chillers.

In general, the operator needs to consider the ambient temperature of the location environment before choosing the type of chiller.

1. How does the glycol chiller system work?

Glycol chiller equipment consists of refrigeration components and pipes containing glycol-water mixture as coolant. The cooling fluid from the refrigeration unit is guided through pipes associated with the heat exchanger surrounding the heating process. After absorbing heat from the related process, the warmed coolant returns to the refrigeration unit for cooling, and then the process is repeated.

Glycol content in chilled water system

For many types of chillers, ethylene glycol is mixed with water in a 60/40 ratio. A higher percentage of ethylene glycol will greatly enhance the antifreeze performance of the mixture. This is useful in situations where rapid cooling is required. In these cases, the process can be cooled to very low temperatures without freezing the coolant in the pipeline.

How does the chiller system work?

Conventional water chillers work according to the principle of heat transfer between fluid and solid media. These cooling systems work by endothermic or vapor compression. The basic components of the water chiller system include a refrigeration unit and a piping system for circulating cooling coolant.

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