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GCC-spec Chillers

Principal Investigators:
Dr. Afshin Afshari, Professor of Practice, Engineering Systems and Management, Masdar Institute
Dr. Peter Armstrong, Associate Professor in Mechanical Engineering, Masdar Institute

Brief:
UAE customers (contractors, building owners) are generally more first-cost sensitive and less operating-cost sensitive than North American customers. Gulf Cooperation Council (GCC) customers, and consequently designers, are highly conservative with respect to adequate capacity. Consequently oversized, standard-performance (or worse) cooling plants are typically installed without regard to the high ambient wet and dry-bulb temperatures, nor the dusty conditions prevalent in UAE. This results not only in high energy use but high discharge temperatures and pressures that lead to high compressor failure rates.

Objectives:
This project is developing chiller designs and specifications that address the foregoing problem while still being life-cycle cost effective based on the true time-of-use costs of supplying power to the cooling equipment. Specific design features to consider will include oversize condensers and evaporators, variable-speed and 2-speed compressors and condenser fans, special condenser surfaces, optimal subcooling control, ejector/expander cycle, and evaporatively-cooled desuperheaters, subcoolers, and condensers. The life cycle operating costs will be estimated based on previously established cooling load profiles (Ali, et al, 2011) and component-based chiller models (Zakula, 2012) that have been validated with variable, as well as fixed-speed, fan and compressor components. A market transformation plan will be developed.

Relevance:
Cooling uses over 40% of all electrical energy produced in Abu Dhabi and over 60% of peak-day energy. It is estimated that drop-in replacement of all cooling equipment with life-cycle cost optimized equipment will reduce cooling energy use by 20-35% with respect to ASHRAE 90.1 2007 equipment (Armstrong, et al, 2009). Savings by replacing older or improperly-sized equipment will be correspondingly higher.