Industrial and commercial chillers play a vital role in cooling all types of buildings and industrial processes. Whether the interior space of a building is used for office, manufacturing, medical laboratory-hospital purposes, residential, institutional, chiller systems provide an effective way to remove excess heat and provide a temperature controlled environment.
The primary function of a chiller system is to remove heat from the internal space and transfer it to the outside. This is particularly important in industrial environments where, for example, processes in manufacturing operations can generate significant amounts of superheat, which can negatively affect process performance and efficiency or create uncomfortable internal conditions.
These may include the burning or heating of raw materials, friction and mechanical use. Removing this heat is necessary to keep the system running properly and efficiently. Such industrial process coolers are different from HVAC systems in residential or commercial environments. Below is a summary of their main components, and how industrial chillers work.
Water Cooled Screw Chiller
Chillers work by sending water to any process that needs cooling. The water extracts heat from the source; the warm water is then sent to the chiller. A portion of the warm water is transferred to the atmosphere in the form of steam. To complete the entire cycle, the chiller system requires four main components.
Evaporator - this is where the extracted process water enters the chiller system. This is converted into a low pressure gas through the use of refrigerant.
Compressor - In this part of the cycle, the compressor converts the low pressure gas into high pressure so that it can flow through to the next step, the condenser.
Condenser - the high pressure gas is cooled by the condenser and thus converted back into a low pressure liquid form.
Expansion valve - as part of the final step of the process, the liquid returns to the expansion valve and is guided back to the evaporator. The cycle can now be restarted.
Chiller systems utilising cooling towers provide a cost effective method of heat dissipation and internal temperature control for almost any type of facility, including industrial process operations. One of their main advantages over other types of cooling systems is that they can achieve quite low water temperatures in the process compared to other methods, such as air cooling systems or systems involving dry heat removal.
Water-driven systems can improve energy efficiency and reduce overall operating costs. For example, air-cooled chillers may require more electricity to operate with a similar amount of cooling.
Chiller systems consume a lot of energy to operate. In fact, statistics show that chiller use consumes approximately one fifth (20%) of all electricity produced in North America. Clearly, there is still room to optimise the operation of these systems - many are estimated to consume up to 30% more energy than the best systems - a considerable waste and a huge unnecessary expense for building operations.
Potential areas for improving the energy efficiency of chillers include
Optimisation of chilled water set points
Improvements to chiller sequencing
Ensuring proper load balancing
Peak demand and cooling tower water management
The advent of Internet of Things (IoT) based technology has provided the conditions for the development of excellent tools for chiller optimisation. Performance and energy consumption can now be monitored in real time from every component in the system.
In addition, advances in IoT control have been shown to allow better control of temperature during the supply and return phases between chillers and cooling towers. These innovations can improve overall performance and reduce energy consumption during the operation of virtually any type or size of chiller system, whether new or existing.
Air Cooled Screw Chiller
Chiller systems are used in many industries for internal temperature control. They become critical, especially in industries where operations and processes generate excessive heat. To keep machines and equipment running properly and to provide personnel with the right internal working conditions, this heat needs to be removed reliably and continuously in the most efficient way possible. Chiller systems effectively achieve this goal.
There are different types of chillers used in commercial, industrial and a wide range of institutional environments. Here is an overview of them, as well as some of their advantages and disadvantages.
There are three main types of industrial chillers.
Evaporative condensing chillers
Each performs exactly the same function - removing heat from the building and thus reducing the internal temperature. They share some of the same components, notably the condenser, but the method of achieving heat dissipation within the condenser differs.
Water-cooled chillers use an external cooling tower to provide water to cool the gaseous refrigerant inside the condenser. After discharging its heat, the refrigerant is converted back into a liquid where it can be recirculated through the phase into a gaseous state before changing back into a liquid again.
Generally speaking, water-cooled chillers are more efficient to operate than air-cooled systems. They are very flexible and can be scaled up to large size capacities as well as small scale cooling requirements. Facilities where space constraints are an issue can also utilise portable water cooled chiller systems. Another advantage to consider is their relatively quiet operation compared to other types.
As the name implies, air-cooled chiller systems use ambient air with the help of a fan to dissipate the heat of the refrigerant in the condenser. The use of air for this heat dissipation process before the condensing step and before returning to recirculation is the main difference between them and water-cooled versions. The amount of heat discharged from this type of chiller can be considerable at its location.
The upfront cost of installing an air-cooled chiller system is often lower than that of its water-cooled counterpart. This is because they do not require components such as cooling towers and pumps. For the same reason, they also tend to be less expensive to maintain. They are a good suggestion when space constraints are an issue and are available in portable versions. In some setups, the heat discharged from the heater is used to heat the interior of the building during the colder months. This helps to offset heating and energy costs.