Experimental study of supercritical CO2 heat transfer in a thermo-electric energy storage based on rankine and heat-pump cycles
Nicolas Tauveron, Edoardo Macchi, Denis Nguyen, Thomas Tartière
Session: Session 1A: CO2 Power System
Session starts: Wednesday 13 September, 10:30
Presentation starts: 10:30
Room: Building 27 - Lecture room 01
Nicolas Tauveron (CEA)
Edoardo Macchi (IMFT)
Denis Nguyen (BRGM)
Thomas Tartière (ENERTIME)
Multi-megawatt thermo-electric energy storage based on thermodynamic cycles is a promising alternative to PSH (Pumped-Storage Hydroelectricity) and CAES (Compressed Air Energy Storage) systems. The size and cost of the heat storage are the main drawbacks of this technology but using crystalline superficial bedrock as a heat reservoir could be a readily available and cheap solution. SELECO2 research project1 considers a thermal doublet consisting in a “hot storage” in a crystalline superficial bedrock (e.g. granite) and a cold storage in an ice pool. The complete system includes a heat pump transcritical CO2 cycle as the charging process and a transcritical CO2 Rankine cycle of 1 – 10 MWe as the discharging process.
Various technical studies are undertaken to assess the performance of such system. Steady-state thermodynamic models have been realized to optimize system efficiency. In addition, unsteady models of geothermal heat exchanger network were developed for the ground heat storage.
An experimental device has been designed and built to test the heat-exchange performance and dynamics. The conditions are intended to reproduce real process dynamics at a laboratory scale. The heat exchanger is at 1/10e scale with a 1.6 m height and 40 mm inner diameter. Temperature (~130°C) and pressure conditions (~12MPa) follow the operating conditions of the real process coupled with a granitic bedrock. First results show that energetic and exergetic performances are better if a specific strategy of short charge and discharge cycles is employed rather than longer charge and discharge phases. Moreover experimental results will be used to improve the above-mentioned numerical simulations and to validate more complex CFD models developed within the project.
1 Project SeleCO2, grant ANR-13-SEED-0004, partners BRGM, CEA, Enertime, ENGIE, IMFT. Project website http://seleco2.free.fr/