What factors affect chiller efficiency and operating costs?

Efficient operation starts with selecting a chiller that is appropriate for the application.

When specifying a recirculating chiller, important information includes:

• Process heat load
• Required fluid temperature
• Required flow rate
• Coolant type
• Any stated pressure requirement
• Ambient operating conditions
• Electrical supply

Selecting equipment around the actual process requirements helps to ensure that the chiller, refrigeration system, and pump are appropriate for the application.

The conditions in which a chiller operates can have a significant effect on its performance.

For an air-cooled chiller, heat removed from the process is rejected into the surrounding air. As ambient temperature increases, rejecting this heat becomes more difficult and the available cooling capacity can be affected.

Correct indoor siting, adequate ventilation, and unobstructed airflow are therefore important.

For applications with more demanding ambient conditions, compatible ATC models may also be available with a High Ambient Configuration.

Most recirculating chillers use surrounding air to reject heat, but a Water-Cooled configuration is available on compatible ATC models.

A water-cooled chiller uses a suitable facility chilled water supply for heat rejection rather than relying on ambient air. This can provide more stable operation, reduce heat rejection into the surrounding room, and offer lower operating noise.

It can also be particularly useful in high ambient environments.

The right configuration depends on the application and the infrastructure available at the installation.

The hydraulic system can also affect how efficiently and reliably a chiller operates.

A chiller pump creates flow, while pressure develops as that flow encounters resistance within the customer’s pipework, fittings, and process equipment. Selecting a pump therefore requires an understanding of both the required flow and the system resistance.

ATC’s current range uses two main pump types:

Centrifugal pumps provide variable flow depending on system resistance and are generally suited to higher-flow, lower-pressure applications.

Positive Displacement Pumps provide more consistent flow as resistance increases and require bypass protection.

The appropriate pump should be selected for the application rather than simply matching a previous pump specification.

A continuous coolant flow path is essential for reliable chiller operation.

Excessive restriction or a blocked flow path can result in overpressure, pump dead-heading, overheating, cavitation, reduced cooling performance, and potential equipment damage.

Pipework, valves, and process equipment should therefore be designed with the chiller’s flow requirements in mind.

The process fluid is another important part of the cooling system.

Fluid type and temperature influence both heat transfer and hydraulic performance. The coolant should be compatible with the chiller and application and maintained in an appropriate condition throughout operation.

Contamination or restrictions within the fluid circuit can reduce heat transfer or affect flow, so the condition of the cooling circuit should form part of routine maintenance.

ATC’s current product development strategy focuses on lower-GWP refrigerants suitable for today’s regulatory environment and future product development.

R290 is ATC’s preferred long-term refrigerant platform. It has ultra-low Global Warming Potential (GWP), and a strong long-term regulatory outlook where refrigerant charge limits and safety requirements can be met.

R454C is used as a lower-GWP transitional refrigerant for applications where R290 is not currently practical.

Older refrigerants including R134a and R407C are now considered legacy refrigerants within ATC’s product strategy and are not being used for new product development.

The refrigerant used is determined by the design of the chiller and is not something that should be selected or changed independently by the customer.

Rather than relying on extensive bespoke modifications, ATC’s current chiller range is structured around predefined configurations, Option Packs, and Accessory Packs.

This allows common application requirements to be addressed using validated and repeatable solutions while maintaining consistent product quality, manufacturing processes, and support.

Depending on the model and application, standard solutions can include high-ambient and water-cooled configurations, together with Option packs for requirements such as low temperature and high temperature operation.

Requirements outside the standard product range can be assessed by ATC Engineering as a non-standard requirement.

Regular preventative maintenance helps a chiller continue to operate effectively throughout its working life.

Keeping heat-exchange surfaces clean, maintaining unobstructed airflow and fluid circulation, checking the condition of mechanical and electrical components, and identifying developing issues can help to prevent deterioration in performance and reduce the risk of unexpected downtime.

Maintenance requirements will vary according to the equipment, application, and operating environment.

There is no single measure that determines the operating costs of a recirculating chiller. Electrical consumption will vary according to the chiller model, process load, operating temperature, ambient conditions, and how the complete cooling system is designed and maintained.

The most effective approach is therefore to consider the complete lifecycle of the cooling system:

Specify the chiller correctly, select the appropriate configuration and pump, operate it within its intended conditions, and maintain it appropriately. 

ATC can help you to identify a recirculating chiller suitable for your process and operating environment.