Air Cooled Chiller VS Water Cooled Chiller

Many regions in the world are grappling with water scarcity. Numerous efforts to desalinate and trade in water are evidence of the magnitude of the problem. The World Bank puts the number of people living with absolute water scarcity at 2bn, a number that could hit the 4.6bn mark within the next 65 years. The water energy nexus has been a regular subject in recent years. Power plants that feed most nations consume a lot of water, either directly or indirectly. When it comes to the feasibility study of a cooling plant, the debate of consuming water or not is very important. Depending on the results of this study, water-cooled or air-cooled chillers will be selected.

What is a chiller?

This device removes heat from a load and transfers it to the environment using a refrigeration system. This heat transfer device is the preferable cooling machine in power plants and other large-scale facilities. It is simply a system consisting of ethylene + water or water reservoir and circulation components. The cooling fluid is circulated from the reservoir to the equipment undercooling. There are also air-cooled chillers, which disperse heat-using fans. These are more recent and common in power plants. In this post, we review the difference between the two technologies, leaving the choice of which one to pick to you. ARANER would be happy to help you in the decision making process. 

Water-Cooled Chiller

Water cooled chiller systems have a cooling tower, thus they feature higher efficiency than air-cooled chillers. Water cooled chiller is more efficient because it condense depending on the ambient temperature bulb temperature, which is lower than the ambient dry bulb temperature. The lower a chiller condenses, the more efficient it is. This system has several essential components including:

Cooling towers

Condenser water pumps

Make-up water pumps

Chillers

TES reservoirs

What are the benefits of a water-cooled chiller? Some users may prefer these chillers because of the smaller size they occupy as compared to air-cooled chillers. These chillers also feature higher efficiency and last longer than the mentioned alternative. Those who would like the equipment to be placed indoors may find the water-cooled machine desirable.

Discover: Chilled Water System on your next project: save up to 40% of energy

In The Evaporator

The role of the evaporator is to produce chilled water. The device releases the water at about 6°C (42.8°F) and pushes it throughout the facility with the help of a pump. A network of pipes passes the chilled water through every necessary section of the building. After exchanging coldness with room air, which blows across the Air Handling Units (AHU’s) and fan coil units (FCU’s), the water is now warmer at about 12°C (53.6°F). It returns to the evaporator where the refrigerant absorbs the unwanted heat and directs it to the condenser. The chilled water is cool once again and it can now continue to cool the facility. Note how this is called “chilled water” throughout no matter the temperature.

In The Condenser

A refrigerant brings unwanted heat from the evaporator and passes through the condenser. There is another loop connected to the condenser- the condenser water loop, which is between the cooling tower and the condenser. After entering the condenser at about 27°C (80.6°F), the water leaves at 32°C (89.6°F) and heads to the cooling tower. Note that at no time do the refrigerant and the condenser contact directly. Heat exchange is only through a pipe wall. The condenser water, with the unwanted heat, goes to the cooling tower for further heat rejection.

In The Cooling Towers

This is where the unwanted heat in a facility ends up. A large fan feeds the unit with air. The air meets with the oncoming condenser water. From the direct contact, the condenser water loses heat to the air. The condenser water goes back to the condenser the cycle continues. These open-topped devices come in many designs depending on many factors. Examples are cross flow, counter flow, natural draft and mechanical draft. Stay with us for coverage of these designs in upcoming posts. This is a good way of settling the cooling tower vs. chiller confusion. However, if you still need more details about the water-cooled chiller components and operation, reach out to our team and you will get help. Now, compare it to the air-cooled chiller discussed below.

Air-Cooled Chiller

Where aesthetics and environmental conditions or water access restrictions exist, the  air-cooled chiller may be applied. Both air-cooled chiller and water cooled chiller depend on an air stream as a means of heat transfer. The difference is that the water-cooled chillers or rather the cooling towers use a humid air stream (ambient air stream + water spray) while the air-cooled chillers use a current of ambient air. Normally water-cooled chiller is cheaper and more efficient, with the disadvantage of high water consumption. ARANER has found a way of combining modern manufacturing methods and advanced technology to achieve highly effective and efficient air-cooled chillers. Owing to that, the company’s chiller plants are very competitive to water chilled chillers in different aspects. For example, these plants are very impressive in terms of footprint, efficiency, and noise. Unfortunately, some people still believe that air-cooled chillers cannot offer quite good efficiencies. What such people only need to check is the performance of these chillers two decades ago is the progressive increase in NPLV rating of air-cooled chillers over the years. Already, many chiller plants in the Middle East and elsewhere have adopted ARANER’s air-cooled designs and have expressed satisfaction. When used in part-load applications, these chillers are very reliable. In summary, here are the benefits of using air-cooled chillers:

No cooling towers

Better environmental stability-no water wastage

Low maintenance costs

Easier to operate and control-tower freezing and tower bypass absent

Chemical costs avoided

Water costs avoided, especially in cities

No water problems to deal with in case of disaster

How do I choose between the two?

The cooling capacity is the main guideline for the choice of the chiller. Equally crucial is the balance between operating costs and capital costs. Some clients will base their buying decision on initial costs. However, a value-based option considers both operational cost and initial cost. To determine the initial cost of each option, add the costs for both contractors and equipment. For the water-cooled chiller, remember to add cooling tower. When it comes to life cycle cost, you have to consider both purchase cost and operating cost. When you evaluate each of the two chillers this way, you are able to determine its total cost. What you must note is that water-cooled chillers normally appear more valuable if you ignore first cost and water cost. However, it is only after you look at the broader costs that the true picture appears clearly.

Other alternatives: hybrid chillers

Hybrid chillers are chillers that can operate as air-cooled chillers under certain conditions and water-cooled chillers under other conditions. They are an interesting alternative for areas with a predominantly dry climate and low water availability. Also, when water availability is not constant or reliable.

It might interest you: Environmental Consideration of Chillers for District Cooling Plants

Water-cooled chiller and air-cooled chiller, the main advantages!

Energy cost remains a major consideration in any powered equipment. Energy-saving measures are being implemented everywhere. While the chiller has direct impact on energy usage, there are other factors to consider. While the water-cooled chiller may be more energy-efficient, it receives stiff competition from air-cooled chiller in terms of installation cost, maintenance cost, number of equipment, and several other aspects. Most importantly, air-cooled chillers avoid water consumption so they are the ideal alternatives in areas with water scarcity or areas with cheap energy but costly water fees. Have you made your choice already? Give us a call today for the most specialized and customized attention. If you enjoyed this post, you maybe want to know different heat rejection condensing technologies.

The Complete Guide to Water-Cooled Chiller Systems

The Complete Guide to Water-Cooled Chiller Systems

What Are the Benefits of Water Cooled Chiller Sytems?

You can enjoy plenty of benefits when you choose this particular water cooled chiller system. First and foremost, it is energy efficient. Compare to air systems, experts agree that it can be 100 times more efficient since they transfer heat more effectively. For businesses that invest in this system, it can mean savings in terms of your utility operating cost.

Another advantage is that it does not require an open space (unlike air systems). You can install them inside a building or in an indoor environment. It is also much safer because unlike in the past wherein chemicals are used as refrigerants, this one is completely safe as it uses water.

What Are Potential Drawbacks in Design?

While there notable benefits from using this system, you should also expect a few potential drawbacks with its use. There is a higher operating cost involved with the initial installation of the system. It requires the addition of other components such as condenser water pumps and cooling towers.

water cooled system components

It also requires more maintenance. The components are exposed to cooled chillers water, which can cause damage and corrosion over time. Hence, it should require a more stringent maintenance procedure to ensure that the system chiller works efficiently for longer.

Water Cooled Chiller System Design

How Efficient is Water Cooled Chiller Sytems?

It is highly efficient. According to industry experts, its efficiency rating can range from 10 to 100 times better than traditional cooling systems. Therefore, a more sustainable option and also better for the environment.

Is It Complicate of the Chillers Water Cooled Chiller Sytems?

No. The concept behind the use of a chiller is the same as any other, except for the addition of a few components such as the cooled chillers water pump and cooling towers. Therefore, it is not complicate to install, use, and maintain.

Water Chiller System

What Water Cooled Chiller Diagram to Install?

Unlike air chillers, the water systems can be installed in an indoor environment or any sealed room. It is the ideal option for those who need a cooling system but does not have access to an open space.

Water Cooled System Diagram

Do You Need To Cycle On And Off The Water Source?

No. You should keep the water supply going at all times. This is to ensure that the system continues to produce cooling effect without causing damage to the system. If the chiller is operating and there is no water, it can cause the coils to freeze. When this happens, it could crack or break. This could compromise the entire system.

What Is The Lifespan of Water Cooled Chiller Sytems?

On average, the lifespan of chillers water cooled is longer than chillers air cooled. The actual lifespan will vary significantly depending on the usage and the maintenance done. Longer lifespan can also be different to the fact that they install indoors so expose the system to harsh environmental factors.

schematic diagram water cooled chiller system

How Do You Maintain chillers water cooled Sytems?

Ongoing maintenance is an essential step so you can increase the efficiency of this system. If you install one for your business, it is important to implement best practices on facility management so it can last longer.

The basic step for maintenance involves inspecting and cleaning the condenser coils. You should also maintain the refrigerant charge to ensure proper cooling. Then, you must maintain the condenser water to ensure proper water flow.

Is Water Chiller More Energy Efficient Than Air Cooled Chillerss?

Yes. Unlike ambient air that can fluctuate, you can expect more stability from a water source. This makes it more efficient to operate in the long run.

How Do You Determine the Cooling Capacity for Project Purpose?

When you buy GESON China water chiller, Compare to air, water has the ability to remove heat 20 times faster. This means that there is a higher cooling capacity with the water chiller than the air cooled chillers. In terms of figure, you can expect 70% cooling capacity when you power the system (compared to only 30% for the air cooled chillers).

Which Type of China Water Chiller is Best For Your Facility?

It depends on what type of facility or building you want to install the cooling system for. For large or high-rise buildings, the water cooled system is the best option. It does not require an open space and it can generate more cooling power. The most common uses for the water chiller are airports, shopping malls, and other similar facilities.

On the other hand, air cooled chillers are best for those that have smaller space available for installation. Since the system is often installed outdoors, its lifespan is often compromised.

Does A Water Chiller Need A Cooling Tower?

Yes. Unlike air cooled chillers that do not need cooling towers, water cooled ones do. Depending on the water source, the cooling tower acts on it to remove any heat. Once the heat is removed, it can disperse cool air into a large space.

Can You Use It for An Commercial Buildings HVAC System?

Yes, chillers are now widely used in many air conditioning units. It does the same process as any type of chiller applications wherein the cooling towers remove the heat from the water. This enables the air conditioner to emit cool air from the fan coil units to cool the space.

chiller cooling system

When to Choose Water Cooled Air Conditioners?

If you are looking for a cooling system that is energy-efficient and long lasting, choose water air conditioners. It also features quiet operation so it is perfect when you want to cool a room or building without causing a lot of disturbance.

How Do You Troubleshoot A Water Cooled Chiller Sytem?

There are several common issues that could arise from the use of a water cooled chiller. It is important to know how to troubleshoot them.

When the chiller does not power up, it could be that there are some loose connections. Other possible causes would be that the power switch is “off”, or that a fuse might have been broken. Make sure to check these possible causes for an immediate fix.

pipe water cooled chiller system

If there is insufficient water flow or it is not pumping water at all, check if the reservoir has enough water to supply the system. Make sure to check the process valve to ensure it is open or that none of the process lines are restricted. A failure in the pump must also be looked into.

Finally, if there is insufficient cooling produced by the system, check the refrigerant. Make sure there is no leak that makes it incapable of removing heat from the water source. You should also check the condenser or air filter to make sure that it is working properly.

Even when you maintain and inspect the chiller regularly, there are still issues that could arise. It is important to know the basic troubleshooting for the system so you can address the cause and ensure proper function.

Water Cooled Chiller Diagram

What are The Common Applications of A Water Cooled Chiller System?

There are plenty of ways to use a water system. It plays a vital role in various industries such as keeping medical machines functioning properly. It is also valuable in the food processing industry in order to preserve meat and other perishable goods by keeping them in a cool storage.

Other industries that can benefit from the use of a water chiller system include the brewery industry, pharmaceutical industry, meat and poultry processing, and retail industry, among others.

Applications of A Water Chiller System

What is The Average Size for This Water Cooled Chiller?

You can find a variety of sizes for water chillers in the market. Choose the size you want according to the cooling capacity in need. Find smaller models that offer 20 ton capacity to larger models of up to a thousand-ton in capacity. Therefore, there are plenty of possibilities when it comes to their use since you can find different models to choose from.

Can You Use Them in An Outdoor Setting?

No. Water chillers are typically used in an indoor setting wherein it is protected from the elements. It does not require an open space like air chillers so it can be installed in an enclosed space or room.

The process of installation for the water system is more complex and time-consuming. However, the cost and effort to install it pays for themselves in the long run because you can enjoy more benefits and a longer lifespan.

How a Chilled Water System Works

Many climates have hot weather. Some places are hot year-round.

But that doesn’t mean that the inside of buildings needs to be hot.

While the temperature outside can sometimes be over 100 °F, the temperature inside the building can be a comfortable 74 °F. This is all thanks to the chilled water system.

Chilled water systems are used in medium and large-sized buildings.

Chiller plants act as a centralized cooling system that provides cooling for an entire building or even multiple buildings. This is because it is often more practical to centralize air conditioning equipment in one location rather than install many pieces of equipment in many different places.

In addition to simplifying access for a building’s maintenance crew, large water chilled systems also provide greater energy efficiency than smaller, individual systems.

An Introduction to Chilled Water Plants

Even though chilled water systems are a new idea to most people, the concept has actually been around since the time of the ancient Romans. In order to cool their buildings, the Romans would run water through the walls to cool the space inside.

It wasn’t until 1902 that Willis Carrier invented modern air conditioning. Then in 1926, Carrier invented the first centrifugal chiller, which made it possible to provide large-scale air conditioning for buildings.

Since then, chillers have undergone much innovation and there are many different types of chillers. However, the purpose of a chiller remains the same: To remove heat from water.

Chilled Water System Basics

Chilled water systems provide cooling to a building by using chilled water to absorb heat from the building’s spaces. At the heart of the water chilled system, a chiller removes heat from water by means of a refrigeration cycle.

Chillers use the refrigeration cycle to remove heat from water

A chilled water system’s refrigeration cycle works by removing heat from chilled water in the evaporator of the chiller. The compressor is what drives the entire process. It also uses the most energy in a chilled water system.

In the condenser of the chiller, the heat is transferred to the condenser water, or directly to the outside air (we’ll talk more about this below).

Chilled Water Loop

The chilled water loop consists of pipes and pumps that move chilled water around a building. A chilled water pump (CHWP) pushes chilled water through the chiller and through the chilled water line around the building.

The chilled water that exits a chiller is called the chilled water supply (CHWS). The chilled water supply temperature is usually about 45 °F.

The chilled water supply is pumped through the chiller and to the building’s various air conditioning units such as air handling units (AHUs) and fan coil units (FCUs):

In the AHUs and FCUs, the chilled water is passed through a heat exchanging coil to reduce the temperature of the coil.
 

While the heat exchanging coil is cooled by the chilled water, a fan blows air through the coil to provide cold air to the building’s space. The supply air temperature that is blown out of AHUs and FCUs is usually about 55 °F.
 

After exiting the heat exchanging coil, the chilled water return (CHWR) returns to the chiller, where it is cooled again, and the process repeats.

Some chilled water cooling system configurations are very simple, while others are more complex:

A simple chilled water cooling system configuration can consist of a single chiller and a single pump.
 

A more complex chilled water cooling system configuration can consist of multiple chillers, multiple pumps, cooling towers, heat exchangers, and all sorts of valves to redirect flow according to the heat load inside of the building.

Next, we’ll talk about a couple of different chilled water system configurations.

Chilled Water Cooling Systems

When a chiller is producing chilled water, the heat that is removed from the chilled water must be rejected somewhere – usually outside of the building. The chiller system is the facilitator of heat transfer between the inside and outside of a building.

There are two main types of chilled water cooling systems: air-cooled chillers, and water-cooled chillers.

Air Cooled Chiller

Air-cooled chillers are almost always located outside of a building and remove heat from the chilled water by exhausting the heat directly to the surrounding air.

Air-cooled chillers exhaust heat from the condenser coil. As warm refrigerant passes through the condenser coil, the outside air blows over the condenser coil and removes heat from the refrigerant.

The refrigerant then passes through an expansion valve, where it rapidly cools and goes through the evaporator, where it cools the chilled water. This process is then repeated all over again.

A chilled water system using an air-cooled chiller

Water Cooled Chiller

Water-cooled chillers are almost always located inside of a building. They work almost the same way as air-cooled chillers. The difference is that they remove heat from chilled water by exhausting the heat to a second, isolated water line called the condenser water line.

The condenser water flows through the chiller and picks up heat. The condenser water then returns to the cooling tower. The cooling tower is almost always located outside of the building and removes heat from the condenser water by evaporating some of the condenser water into the atmosphere.

As some of the condenser water evaporates, heat is removed from the condenser water, and the cool condenser water flows back to the chiller. This process is then repeated all over again.

A chilled water system using a water-cooled chiller

Water-cooled chiller systems are very energy efficient. However, due to their complexity and many different parts, they are often more expensive to install and maintain. For this reason, you will usually only find them in large buildings. This is because the energy savings outweigh the cost of installing and maintaining the system.

However, water-cooled chillers are starting to make an appearance in small buildings as well. Recent advancements have made it practical to install and maintain water-cooled chillers in buildings that usually would not have one.

Chiller Plant Optimization

Chiller plants are often a significant portion of a building’s energy usage. According to the U.S. Energy Information Administration, 15% of the energy used in commercial buildings is for cooling.

When you consider that chillers are often one of the largest consumers of energy inside a building, their performance can have a huge impact on operational costs. For this reason, the efficiency of a chiller plant is often closely monitored for potential improvement.

Optimizing a chiller plant is a complex task that involves gathering data and making calculations. These calculations determine how to best operate the chiller plant equipment.

For instance, during the cool night hours, it may be more efficient to raise the chilled water supply temperature setpoint of the chiller. Raising the chilled water supply temperature setpoint will allow the chiller to not work as hard.

Conclusion

Chilled water systems are typically used for cooling medium and large buildings. While the upfront cost of a water chilled system can be a lot, the greater energy efficiency and lower maintenance costs usually make up for it.

A chiller is simply a facilitator of heat transfer between the inside and the outside of a building, and the chilled water system can have many different configurations. Air-cooled chillers and water-cooled chillers are the most commonly used types of chillers.

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