Effect of moisture on the efficiency and power density of a liquid piston air compressor/expander

Anirudh Srivatsa, Perry Y. Li

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


For a compressed air energy storage (CAES) system to be competitive for the electrical grid, the air compressor/expander must be capable of high pressure, efficient and power dense. However, there is a trade-off between efficiency and power density mediated by heat transfer, such that as the process time increases, efficiency increases at the expense of decreasing power. This trade-off can be mitigated in a liquid (water) piston aircompressor/ expander with enhanced heat transfer. However, in the past, dry air has been assumed in the design and analysis of the compression/expansion process. This paper investigates the effect of moisture on the compression efficiency and power. Evaporation and condensation of water play contradictory roles - while evaporation absorbs latent heat enhancing cooling, the tiny water droplets that form as water condenses also increase the apparent heat capacity. To investigate the effect of moisture, a 0-D numerical model that takes into account the water evaporation/ condensation and water droplets have been developed. Results show that inclusion of moisture improves the efficiencypower trade-off minimally at lower flow rates, high efficiency cases, and more significantly at higher flow rates, lower efficiency cases. The improvement is primarily attributed to the increase in apparent heat capacity due to the increased propensity of water to evaporate.

Original languageEnglish (US)
Title of host publicationAdvances in Control Design Methods, Nonlinear and Optimal Control, Robotics, and Wind Energy Systems; Aerospace Applications; Assistive and Rehabilitation Robotics; Assistive Robotics; Battery and Oil and Gas Systems; Bioengineering Applications; Biomedical and Neural Systems Modeling, Diagnostics and Healthcare; Control and Monitoring of Vibratory Systems; Diagnostics and Detection; Energy Harvesting; Estimation and Identification; Fuel Cells/Energy Storage; Intelligent Transportation
PublisherAmerican Society of Mechanical Engineers
ISBN (Electronic)9780791850695
StatePublished - 2016
EventASME 2016 Dynamic Systems and Control Conference, DSCC 2016 - Minneapolis, United States
Duration: Oct 12 2016Oct 14 2016

Publication series

NameASME 2016 Dynamic Systems and Control Conference, DSCC 2016


OtherASME 2016 Dynamic Systems and Control Conference, DSCC 2016
Country/TerritoryUnited States

Bibliographical note

Publisher Copyright:
Copyright © 2016 by ASME.


  • Compressed air energy storage (CAES)
  • Condensation
  • Evaporation
  • Heat transfer
  • Isothermal compressor/expander
  • Liquid piston
  • Renewable energy


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