Air cooled chillers are a common type of equipment cooling device. Simply speaking, the difference between them and water cooled chillers lies in the cooling medium used. For example, water cooled systems use water to transfer heat, while air cooled systems use air to dissipate the heat into the surrounding environment. So what exactly is the air cooled water chiller working principle? In this article, I will provide a detailed explanation.
Physical Principles of Air Cooled Water Chillers
Phase change
We can say that the phase change of the refrigerants is a base of an air cooled water chiller’s whole working process, it does use this rules to achieve effective exothermic and endothermic processes.
When the refrigerant vaporizes, it will absorb the heat from the circulating water and lower the temperature of it, while releasing the heat when it is condensing, finally, it will return to a liquid state and starting a new cooling cycle.
The Relationship Between Pressure and Boiling Point
The effect of pressure on the boiling point of a gas is another fundamental principle governing the operation of air cooled water chillers, and it plays a crucial role in your chiller system.
After the expansion valve reduces the refrigerant’s pressure, its boiling point decreases too, thus enabling it to absorb more heat from the circulating water during vaporization and cool it. On the other side, when the compressor increases the refrigerant’s pressure, its boiling point will rise and bring easier condensation for the refrigerant into a liquid and the release of additional heat. This characteristic allows the refrigerant to absorb or release greater amounts of heat during phase transitions, enabling effective cooling for your equipment.
Heat Exchange
The heat exchange is also the fundamental principle of your air cooled water chiller and it is this process that achieve the cooling effect. The principle is also easy to understand too, and can be conclude as the heat from the higher temperature object always transfers to the lower temperature one. That is why the heat from the circulating water is transferred to the refrigerant, and the refrigerant’s heat will be transferred to the surrounding air too.
Specific Operating Process of Air Cooled Water Chillers
The specific operating process is also straightforward for you to learn. Typically, your equipment is connected to the chiller via the pipes, which serves as the circulation pathway for the cooling water. This water will flow through the pipes into the evaporator of the air cooled chiller, where it comes into contact with the refrigerant and facilitates heat transfer.
The refrigerant that has been depressurized by the expansion valve readily will vaporize during this process, it can continuously absorb the heat from the circulating water. At the same time, the gaseous refrigerant is drawn into the compressor, where it is heated and pressurized, then will transform into a high pressure gas. While the cooled circulating water will then flow back through the piping to the equipment, continuing its cooling cycle.
Then, the high pressure refrigerant gas will enters the condenser from its coils. Fans installed on the condenser draw in surrounding air, which carries away the heat from the refrigerant. This causes the refrigerant to condense into a liquid, releasing additional heat. It then passes through the expansion valve again to further reduce its flow rate and pressure before returning to the evaporator to begin a new cooling cycle.
Main Components of an Air Cooled Water Chillers And Their Functions
Evaporator
We can call the evaporator as the start of the whole cooling cycle, as the circulating water needs to enter this component to achieve the cooling effect, and it is here the refrigerant comes into contact with the circulating water and absorbs its heat, then undergoes vaporization and the following condensation process.
Compressor
The compressor’s function is to draw in the refrigerant gas and compress it into a high temperature, high pressure state by changing the chamber volume. At this state, the refrigerant’s boiling point also rises, making it more conducive to converting into liquid within the condenser and releasing heat into the surrounding air. In actual applications, you can achieve a higher efficiency by connecting the compressors in parallel or series.
Condenser
The high temperature, high pressure refrigerant gas releases its heat into the surrounding air within the condenser, where it condenses into a liquid with the assistance of a fan. It then flows back to the compressor via the expansion valve.
To ensure your chiller maintains a sufficiently long service life, you need to note that copper fins are more suitable for condenser coils due to their equally excellent thermal conductivity. Additionally, to prevent poor condenser performance, you must protect it with safety grilles to avoid clogging from dust or foreign objects, which could decrease the condensation efficiency.
Cooling Fan
The role of the cooling fan is also necessary, it is usually installed near the condenser and can blow in the air outside to accelerate the heat dissipation process.
Expansion valve
As we mentioned above, the expansion valve is used to reduce the refrigerant pressure, but how can it perform this process?
Well, when the expansion valve receives the high pressure liquid refrigerant, it will decease the flow rate of the liquid refrigerant, thus it can lower the temperature and the pressure of the liquid. At the same time, it maintains the pressure differential between the two sides of the expansion calve. This process is similar to the effect of a dam, right? As the refrigerant enters the evaporator again, the low temperature, low pressure liquid refrigerant will vaporize too, and keep repeating this cooling cycle.
There are seven types of expansion valves are available for your selection, including thermal, low pressure, high pressure, electronic, and automatic models. Their common purpose is to achieve pressure reduction by regulating refrigerant flow.
Water Pump/Tank
The pump provides the driving force to ensure smooth and steady flow of cooling water, drawing it into and discharging it from the chiller. While the water tank works as a buffer to stabilize temperature fluctuations before the cooling water enters the chiller. More importantly, it stores sufficient circulating water to maintain consistent pressure throughout the water circulation, preventing frequent machine start stops caused by insufficient water supply during high demand cooling applications.
FAQ：
Q: What are the Differences of Working Process between Air Cooled Chillers and Water Cooled Chillers?
A: when we talk about the working process of there two types water chillers, one key difference between air cooled and water cooled chillers is the method to dissipate their heat.
Air cooled systems use air to take away the heat, while water cooled systems use water circulation to remove heat from the refrigerant and they always require a cooling tower to complete this work. Compared to the air, water possesses a higher specific heat capacity and enables more efficient heat exchange. Therefore, water cooled chillers are aways used in applications with greater cooling demands.
Of course, we cannot definitively conclude that which is better. The specific choice need to be made depending on your spercific application requirements and operational environment.
Q: What are the Signs of the Components Indicating That I Need To Change My Air Cooled Water Chiller?
A: When your air cooled chiller experiences increased noise from the compressor or fan, poor heat dissipation from the condenser, or even refrigerant leakage, you must immediately shut down the unit for inspection. If such issues persist for a long time and are difficult to repair, your chiller is likely to reach the end of its service life and requires immediate replacement.
Q: How to Maintain The Main Components Of An Air Cooled Water Chiller?
A: In fact, different components of air cooled chillers do require different maintenance approaches.
- Its evaporator needs regular inspection and cleaning to prevent blockages caused by scale or debris.
- For the compressor, you need to monitor its operational noise levels and perform regular lubrication to prevent wear and tear from affecting performance.
- Due to the fin structure, The condenser is prone to dirt accumulation. Thus regular cleaning is essential for you, along with ensuring the unobstructed airflow to maintain good functionality.
- As for the expansion valve, it requires periodic checks for unimpeded flow to prevent blockages that could disrupt the normal circulation of refrigerant liquid.
Q: Can Air Cooled Water Chillers Operate 24/7?
Yes, air cooled chillers can operate continuously around the clock, especially in industrial settings. However, it’s crucial for you to place them in a suitable environment, when installing, you need to avoid high temperatures or direct sunlight, as these conditions may shorten the unit’s lifespan.
Final thoughts
Since 1999, Chillerone has been dedicated to manufacturing energy saving, high performance, and certified air cooled systems. With over 20 years of extensive experience, we offer a comprehensive range of air cooled chillers while continuously innovating and introducing the latest technological models.
Our chillers offer cooling capacities ranging from 5 tons to 200 tons, achieving temperature control from 5°C to 35°C. They are widely applicable across industries including laser manufacturing, food processing plants, electroplating facilities, plastics production, healthcare, and industrial and commercial buildings, and so on.
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