Chiller units are refrigerant systems that help cool commercial spaces, machinery, industrial operations, and industrial chemicals. Two of their biggest advantages are that they are energy and cost-efficient.
Chillers provide a continuous flow of coolant to the cold side of a process water system at the desired temperature of 50°F. The refrigerant is then pumped through the process pulling the heat out of one area of a facility.
Chillers are categorized by types. The two main types are vapor compression and vapor absorption chillers.
Vapor compression chillers use an electrically driven mechanical compressor to force a refrigerant around the system while vapor absorption chillers use heat to move the refrigerant around the system.
Vapor compression chillers are the most common and fall into two subcategories: air-cooled chillers and water-cooled chillers.
Water-cooled chillers tend to be more efficient than air-cooled chillers. When water evaporation is used to dissipate heat, less energy is used versus blowing air across a hot surface. Water has a higher heat capacity than air so it is much easier to remove the heat. Water chillers when properly maintained will tend to last a lot longer than air-cooled chillers.
Air-cooled chillers cost less to install as they have less equipment and require less space. Rooftop installation negates the need for a mechanical room and frees up more space within the building. Typically, they do not have as long a service life as water-cooled chillers due to exposure to the outside elements.
Chillers are further categorized by the type of compressor used: centrifugal, screw, reciprocating, and scroll chillers.
A centrifugal chiller uses rotating impellers to compress the refrigerant and move it around the chiller. The majority of centrifugal chillers are water chillers. These are used for medium to large cooling loads and offer high cooling capacity in a compact design.
Centrifugal compressors have better full-load efficiency, and screw compressors can achieve comparable part-load efficiencies.
Screw chillers are also used in both water and air chillers and are ideal for small to medium cooling loads. They use two interlocking rotating helical rotors to compress the refrigerant and capacity is controlled via speed control or slider.
Screw compressors work by using two interlocking rotating helical rotors to compress the refrigerant and they are preferred for part-load applications. These are stable down to about 10% capacity, where centrifugal compressors begin to surge at around 20% to 40% capacity.
Reciprocating compressors have two types: air-cooled or water-cooled. They use cylinders with pistons acting as pumps to increase coolant pressure, much like a car engine. Reciprocating chillers are smaller than centrifugal chillers and can cope with the specific demands from load on the system.
Scroll compressors are most often used for small buildings with cooling loads under 200 tons or 700 kW. A scroll compressor works by using two interleaving scrolls (one scroll within the other) to compress the refrigerant. Usually self-contained, scroll compressors are used in both air and water coolers. They are known for quiet operation and their dependability.
Whether it's for rooftop chillers, light commercial or industrial applications, Ohio Heating & Refrigeration has solutions for air conditioning and heating that are designed to meet a wide range of building and application regulations. Call us at 614-863-6666 to learn more.