Developing and investigating a Novel Compressed Air energy Storage (CAES) system using a Liquid Piston Gas Compressor/Expander (LPGC/E)

  • Seyedehmansoureh Khaljani

Student thesis: Doctoral ThesisDoctor of Engineering


This research aims to improve the performance of the Liquid Piston Gas Compressor/Expander (LPGC/E) for the application in small scale Compressed Air Energy Storage (CAES) systems in order to tackle the challenge of unsteady energy supply by renewable energies such as wind and solar. The LPGC/E technology is in developing state and has been proposed to overcome the drawbacks of the solid piston air compressors/expanders. So, most of the research conducted in CAES with LPGC/E are in a pilot-scale and small-scale. Compared to large-scale CAES systems that rely almost invariably on underground air storage in caverns, small-scale overground CAES systems with their highly flexible and adaptable characteristics have attracted interest in recent years. Since, LPGC/Es are more efficient while working isothermally, experimental and modelling research have analyzed different heat exchange materials (e.g. metal foam, interrupted plate, aqueous foam) inside the LPGC/E cylinder in order to achieve near-isothermal compression/expansion processes. However, manufacturing of these heat exchangers is challenging and due to the complex geometry of these heat exchangers, detailed measurements and prediction of the local flow and thermal fields inside these heat exchangers are difficult. High operating pressure and temperature in the LPGC add extra complexity to the problem. This makes the experimental and modeling analysis of such heat exchangers in LPGC/E to be very challenging. The present work examines easy to manufacture and simple geometry heat exchangers (parallel plate inserts) in order to improve the efficiency of the LPGC/E through achieving near-isothermal compression/expansion processes. The system’s performance is analysed using numerical approaches, which are validated against experimental data. For the numerical study, the Reynolds-averaged Navier–Stokes equations (RANS) are solved by deploying the k-ε turbulence model to explore the details of the flow and thermal fields in the LPGC with parallel plate inserts. Further, a detailed parametric study is performed using the CFD model in order to identify an optimum plate geometry for achieving the maximum efficiency of the LPGC. For validation of the model and demonstration of the achievable efficiency, an experimental prototype was developed in collaboration with the industrial partner (B9 Energy Group).

Date of AwardJul 2022
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsRenewable Engine Program
SupervisorAdrian Murphy (Supervisor) & Marco Geron (Supervisor)

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