Optimal Efficiency-Power Tradeoff for an Air Compressor/Expander

Andrew T. Rice, Perry Y. Li, Caleb J. Sanckens

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


An efficient and power dense high pressure air compressor/expander (C/E) is critical for the success of a compressed air energy storage (CAES) system. There is a tradeoff between efficiency and power density that is mediated by heat transfer within the compression/ expansion chamber. This paper considers the optimal control for the compression and expansion processes that provides the optimal tradeoff between efficiency and power. Analytical Pareto optimal solutions are developed for the cases in which hA, the product of the heat transfer coefficient and heat transfer surface area, is either a constant or is a function of the air volume. It is found that the optimal trajectories take the form "fast-slow-fast" where the fast stages are adiabatic and the slow stage is either isothermal for the constant-hA assumption, or a pseudo-isothermal (where the temperature depends on the instantaneous hA) for the volume-varying-hA assumption. A case study shows that at 90% compression efficiency, power gains are in the range of 500-1500% over ad hoc linear and sinusoidal profiles.

Original languageEnglish (US)
Article number021011
JournalJournal of Dynamic Systems, Measurement and Control, Transactions of the ASME
Issue number2
StatePublished - Feb 1 2018

Bibliographical note

Funding Information:
• National Science Foundation (Grant No. EFRI-1038294).

Funding Information:
• Center for Compact and Efficient Fluid Power, a National Science Foundation Engineering Research Center (Grant No. EEC-0540834).


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