Air-cooled vs Water-cooled compressor
- Jul 4, 2023
An air compressor is a tool that generates energy to power business tools and equipment. Air compressors generate heat as they work, so compressed air needs to be cooled with air or refrigerated liquid.
Whether your business chooses a water-cooled compressor or an air-cooled compressor depends on your commercial space’s location, tools, and size. Learn some comparisons between air-cooled vs. water-cooled compressors to help you decide.
How does an air-cooled compressor work?
Air-cooled compressors use air to decrease the temperature of the compressed air and any other materials present. When the compressor heats up, the air cooling circuit reduces the hot air through the fan and radiator. Air-cooled compressors are the most common cooling system and are easier to use than water-cooled systems.
Industry can save utility bills by using the energy to heat buildings or power preheating batteries to recover heat losses from air-cooled compressors. The circuit directs heat to the area with the fan, but if the building doesn’t need more heat, the unit releases the warm air into the atmosphere, controlled by a thermostat or air damper.
How does a water-cooled compressor work?
The compressed air and any other materials present during compression are cooled using liquid coolant from an external unit in water-cooled compressors. The cooling circuit reduces heat through shell and tube exchangers. Water cooling is more common on higher-horsepower machines.
Companies can reuse the water the compressors produce in hot water heating systems, typically for showering, cleaning, or washing. A water-cooled screw compressor can allow a business to invest in a smaller water heater since you won’t need as much hot water.
Why does your air compressor need a cooling system?
Air compressors generate heat—and a lot of it. One of the significant considerations in compressed air system design is keeping the air compressor cool.
In oil-injected rotary screw air compressors, most of the heat is removed internally by circulating oil (also known as coolant). The air leaving the compressor is very hot and must be cooled before it goes downstream; typical outlet temperatures for oil-injected screw compressors can exceed 160°F. Discharge temperatures from oil-free air compressors or two-stage reciprocating compressors may be 300-350°F. These high temperatures can cause problems downstream in compressed air systems, especially air dryers.
Air dryers are rated for inlet temperatures no greater than 100°F. When the temperature is high, the dryer does not work effectively. Warmer air carries more moisture, stressing the drying system. If the dryer doesn’t remove enough moisture, it can cause condensation to form in other parts of the distribution system as the air cools. Too much heat can cause other problems:
Excessive heat can degrade seals and wash away lubricant in downstream tools and equipment, leading to premature failure of system components.
Failure to control the heat generated by air compression will heat the compressor room and surrounding environment, potentially causing the air compressor itself to overheat.
If the compressor is running indoors, the excess heat generated by the compressor can stress the air conditioning system in summer.
Energy costs for air cooling vs. water cooling
When considering the energy costs of each air compressor cooling system, you should keep the following factors in mind:
a) Energy consumption
Air-cooled units require more electricity than water-cooled units.
b) Electricity bills
Water-cooled compressors cost a lot of money for electricity, water, and water treatment so you can save money with an air-cooled unit.
c) Ability to recover resources
Compressor cooling systems provide reusable resources to compensate for energy bill costs. If you can reuse water from your water-cooled compressor to preheat your boiler, you can save on gas and heating bills. You can also use the hot air from an air-cooled compressor to warm a room and power a fluid heat exchanger.
Air-cooled compressor requirements
Air-cooled screw compressors require sufficient cooling air and space to provide adequate airflow. Improper planning can lead to problems with temperature regulation in commercial facilities. Businesses can experience equipment failure and unplanned downtime if the compressor room gets too hot.
To protect your equipment and continue your workflow, install ductwork from both sides of the compressor so air can circulate throughout the space. You can also use the heat from the vents to heat your commercial space in winter. If your business needs more space for additional equipment, setting up a water-cooled compressor is best.
Water-cooled compressor requirements
Water-cooled screw compressors require high-quality cooling water to function. If you get your water from a lake, ocean, well, or river, you need cooling towers and closed-loop systems to filter the water and prolong the system’s life.
Unless your building already has this equipment, you will need to include the cost of purchasing, installing, and maintaining this new machine and the water-cooled compressor. If you have a closed-loop cooling system on the site, ensure it can accommodate your water-cooled compressor before installing it.
Which system should you choose?
Air compressors can serve a variety of industrial applications, but you need to choose the best type for your particular business. Here are some factors to consider when looking for a suitable air compressor:
a) Operating and resource costs
With the cost of water conditioning on the rise, it is essential to consider how much you will pay to use and maintain your equipment. Since water-cooled air systems utilize more water to reduce the heat of the air, they are expensive. Air-cooled screw compressors do not use as much water to power their products and have lower upfront and installation costs.
b) Air demand requirements
When considering air demand requirements, consider the product’s cubic feet per minute (cfm) rating, horsepower (hp), and pounds per square inch (psi) rating. The unit’s horsepower offers more significant potential for meeting the high air demands. The cfm rating tells how much air the compressor can easily produce per minute to give you the proper psi. Look at cfm and psi ratings to determine which will meet your tool and energy requirements.
c) The type of tool used in your industry
Consider the horsepower requirements of your equipment and find out which cfm and psi ratings are suitable for your air compressor. If you use your
d) The layout of the compressor room
Before choosing an air compressor, ensure the room has enough space. If space is an issue, you can purchase several smaller compressors and place them in multiple areas around the plant instead of purchasing one large compressor. Remember that most less horsepower compressors are usually unavailable in water-cooled models.
e) Compressor room ventilation
Air-cooled compressors require adequate airflow to operate and regulate temperature. If the room is not adequately ventilated, the area may become too hot, and equipment may shut down, delaying the project. You’ll also want to keep the air-cooled compressor away from hot boiler rooms or tools occasionally; you can invest in a smaller unit, but if you run them consistently, you should purchase a larger unit.
fumes. Water-cooled compressors are better suited for tight spaces and higher temperatures.
When considering these factors, remember that one type of screw air compressor is not better. Your choice of air-cooled or water-cooled compressor will depend on your specific application and location. Discuss your options with BISON before deciding which suits your industry.
frequently asked questions about Air-cooled vs Water-cooled Compressor
How do air-cooled vs water-cooled air compressors affect energy costs?
Water-cooled units require less electricity than air-cooled compressors. Still, customers should also consider the cost of electricity for the cooling system, water, and water treatment costs when choosing a water-cooled unit. Air-cooled compressors are usually more cost-effective once these expenses are factored in.
On the other hand, some customers use cooling water to preheat factory processes, such as boilers, to save on gas and heating bills. And then they realized saving in that area.
What are the applications of air-cooled air compressors?
- It is used to heat buildings
- Any preheated battery can be charged with it.
- They produce compressed air for cylinder filling.
- Provides support for tools such as jackhammers.
What are the applications of water-cooled air compressors?
- It is used where there is a lot of water.
- Therefore, it can be installed near water bodies such as lakes or rivers.
- It is also used to heat buildings.
Does the water-cooled compressor need to purchase a cooling water tower?
Water-cooled compressors need cooling water; that's obvious, right? Water quality is also an issue. The better the water quality, the longer the compressor heat exchanger will last. So you typically see closed-loop cooling systems that control water quality rather than city water. Purchasing these additional devices with on-site closed-loop cooling systems may only make sense. Purchasing a closed-loop system with a cooling tower will significantly increse the capital cost of purchasing a new compressor. The system's operating cost must then be added to the operating price of the compressor, further expanding the lifetime cost of the compressor. Many large plants already have cooling towers for other equipment, so it becomes a question of whether the cooling tower can provide the required flow with excellent water quality.
