2021 AZAPPA: Steps for Improving Air-Cooled & Water-Cooled Chiller Performance and Energy Efficiency

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Издатель Jun 9, 2021

PRESENTATION ABSTRACT: Jim Crockett, PE, and Greg Jimmie presents the major factors impacting the efficiency of air- and water-cooled chillers and discuss strategies to maximize the energy efficiency of chiller performance. Water cooled chiller efficiency can be improved by instituting a control reset strategy which responds dynamically to system cooling demand. The chilled water system should operate at design conditions when needed, but can improve energy efficiency at non-peak conditions. 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 setpoints can be reset based on the AHUs’ capability to maintain their collective air temperatures. Condenser water temperature, in general, should be as cold as outside air conditions permit, with a low limit dictated by the chiller manufacturer. Because air-cooled chillers are ‘packaged’ items, engineers rarely consider whether they are operating efficiently. By understanding the components 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 percentage of condenser surface used for condensing refrigerant. Presenters also discuss hardware and control modifications that may help maximize the condenser area used for condensing refrigerant, by de-superheating refrigerant vapor, or using pumps to pressurize refrigerant condensate.

3 LEARNING OBJECTIVES:
• Understand the relationship between airside and waterside operation of a cooling system
• Understand how to use dynamic temperature resets to optimize system efficiency
• Discuss potential hardware and control upgrades to improve air-cooled chiller efficiency

3 OUTCOME GOALS:
• Identify factors that can impact the efficiency of air-cooled chillers
• Recognize opportunities in your systems for gaining efficiency
• Increase awareness of packaged units and their impact on energy consumption