CARBOSOLA

Commercial facilities usually generate electrical energy by open, direct heated Brayton or Joule processes (gas turbines) and closed, indirect heated Rankine processes (steam circuit). Instead, a novel and innovative concept suggests sCO₂ as a working fluid for the Brayton process. Thereby, the low fluid viscosity at high density enables compacter components and small plant foot prints. Furthermore, numerous studies underline the potential and higher efficiency of sCO₂ power cycles in comparison to conventional energy conversion units.
In the frame of the CARBOSOLA project the design and commissioning of an operating technical scale facility with sCO₂ as a working fluid was performed at the Helmholtz-Zentrum Dresden-Rossendorf. Temperatures up to 520 °C at 300 bar and mass flow rates of 1.32 kg/s are possible.

Experimental studies will focus the components performance and durability as well as generic fluid dynamic phenomena. The data obtained in the facility foster modelling and simulation of fluid flows and heat transfer in sCO₂ power cycles. The challenging operation conditions give valuable insights for a wide range of topics. Relevant questions concern the material behavior, the structural and fluid dynamic integrity as well as the design of the components at temperatures above 500 °C. Special attention is on the part load behavior of the compressor, the thermal fluid dynamics and heat transfer of the process as well as close critical condensation. Future work will focus the process dynamics for power cycles operated with fluid mixtures or impurities and the performance of the affected components. Consequently, solutions for dynamic sealing of the turbomachinery and the existing measurement and safety technology will be developed and evaluated. Moreover, examinations of various start up and shut down processes as well as operation under different load curves can be addressed.

The construction and the operation of a potent test environment will contribute to the commercialization and the optimization of sCO₂ based power plants as an integral part of the energy system.

References

• Unger, S.; Müller, J.; Bangalore Mohankumar, M.; Rath, S.; Hampel, U.
  Numerical dimensioning of a pre-cooler for sCO₂ power cycles to utilize industrial waste heat
  Energies 14(24), 8278, (2021) DOI: 10.3390/en14248278

Funding

Supercritical carbon dioxide (sCO₂) as alternative working fluid for bottoming cycle and solar thermal application - CARBOSOLA (BMWi 03EE5001D). The authors are responsible for the presented content.