Comparing Chillers – Screw vs Scroll Compressors

Your company therefore needs a new chiller for the manufacturing process in your factory. How do you decide on the right chiller for you? Making the right decision can be a daunting task for any plant manager or engineer. You get it wrong and your plant and your job prospects could be in big trouble. Let's discuss some of the options you have at hand.

Decision points when buying an industrial chiller

The first part of the buying process is deciding whether you need an air-cooled or water-cooled chiller. Now, if you are simply replacing or upgrading an old unit, you may be able to replace that unit with the same type of chiller. However, if you are dealing with a new installation, then you will need to look at your options.

Air cooled chillers vs water cooled chillers

The two most popular types of chillers are air-cooled or water-cooled. The "air" or "water" cooling name refers to the type of condenser used by the chiller to cool the refrigerant.

 Air Cooled Screw Chiller   

Air Cooled Chillers

Custom screw chillers are the most commonly used chiller system because they are a self-contained system. No additional external components are required. These systems are less efficient than water cooled chillers but are more attractive because they are self-contained. Air-cooled scroll chillers are relatively easy to install and start up.

Water cooled chillers

Water cooled chillers require an external cooling tower and cooling tower supply pump to cool the water cooled condenser. If your plant already has an existing cooling tower with excess capacity available, then this is the best option for you to consider. Once you have decided on an air-cooled or water-cooled chiller, you now have to make some more difficult decisions.

Screw vs. scroll compressors

If you are looking for a relatively small chiller (under 30 tonnes), you must buy a scroll chiller. If your cooling needs exceed 30 tons, you can make a decision. Do you use a scroll compressor or a screw compressor. When comparing screw and scroll chillers, there are several things to consider when making this decision.

Water Cooled Scroll Chiller     

Scroll chiller compressors

Scroll compressors are limited in size. Although technology is constantly improving and increasing its size, the largest scroll compressor you can buy today is 40 HP. therefore, if you need a larger cooling load, you will need multiple compressors. While this may be a benefit, you need to ensure that you do not install multiple compressors on a single circuit.

Scroll compressors vs. screw compressors

Scroll compressors fit into a good niche market. They are ideally suited to smaller process applications - especially when operating times are more dispersed (< 24 hours/day). We classify scroll units as medium-sized process chillers. Depending on the environment, scroll chillers can handle longer operating times.

If you plan to run your plant 24/7 and meet the load requirements (over 30 tonnes), we would always recommend an air-cooled screw chiller over a scroll system. Screw compressor systems offer better capacity control options, are fully serviceable and have a wider operating range.

Choosing the right evaporator for your chiller

Another consideration is the evaporator of your chiller. In any application over 20 tonnes we usually recommend a DX shell and tube evaporator on a brazed plate.

Using with a shell and tube evaporator will give you a longer life and better durability. With the ability to manufacture shell and tube vessels using custom materials and thicker tube walls, evaporators can be used to handle direct cooling of corrosive or even aggressive liquids.

We hope that this overview has helped you to make the decision to purchase a new chiller or to replace it. While one of our main objectives is obviously to sell and manufacture first class cooling equipment, our priority is to provide you, the customer, with enough information to make an informed and educated decision. Our Huazhao Refrigeration Equipment can provide an immediate quote for your chiller requirements.