In this webinar, presenters explore the major factors that impact the efficiency of air-cooled and water-cooled chillers and discuss several strategies to maximize the energy efficiency of chiller performance. Water cooled chiller efficiency can be easily improved by adopting a control reset strategy that responds dynamically to a system cooling demand. Ideally a chilled water system is only operating at design conditions when the building needs it but is also able to take advantage of lower cooling demand conditions to reduce energy consumption. System pressure setpoint can be reset by utilizing Variable Frequency Drives (VFDs) on the chilled water pumping system that responds to Air Handling Unit (AHU) valve positions, then chilled water temperature setpoint can be reset based on the AHUs’ capability to maintain their collective air temperatures. Condenser water temperature in general should be made as cold as outside air conditions permit with a low limit as dictated by the chiller manufacturer.

Because air-cooled chillers are ‘packaged’ items, engineers frequently ignore or are unaware of how to evaluate whether they are operating efficiently. By better understanding the components at play in the air-conditioning refrigeration cycle, it may be possible to add controls or components to increase their efficiency beyond factory-rated performance. Compressor energy can be substantially reduced by maximizing the surface area of the condenser used for condensing refrigerant. Presenters also discuss hardware and control modifications that may help maximize the condenser area used for condensing refrigerant, instead of de-superheating refrigerant vapor, or transporting refrigerant condensate.

Learning Objectives

• Understand the relationship between airside and water side operation
• Understand system optimization to ebb and flow the dynamic temperature resets
• Identify factors that can impact the efficiency of air-cooled chillers
• Discuss hardware and control upgrades being explored to improve air-cooled chiller efficiency