Understanding and reducing energy and costs in industrial cooling systems

Abstract

Industrial cooling remains one of the largest potential areas for electrical energy savings in industrial plants today. This is in spite of a relatively small amount of attention paid to it by energy auditors and rebate program designers. US DOE tool suites, for example, have long focused on combustion related systems and motor systems with a focus on pumps and compressors. A chilled water tool designed by UMass was available for some time but is no longer being supported by its designers or included in the government tool website. Even with the focus on motor systems, auditing programs like the DOE's Industrial Assessment Center program show dramatically less energy savings for electrical based systems than fossil fueled ones. This paper demonstrates the large amount of increased saving from a critical review of plant chilled water systems with both hardware and operational improvements. After showing several reasons why cooling systems are often ignored during plant energy surveys (their complexity, lack of data on operations etc.), three specific upgrades are considered which have become more reliable and cost effective in the recent past. These include chiller changeouts, right sizing of systems with load matching, and floating head pressures as a retrofit. Considerations of free cooling and improved cooling tower operations are shown as additional "big hitters”. It is made clear that with appropriate measurements and an understanding of the cooling system, significant savings can be obtained with reasonable paybacks and low risk.