Abstract

Within the framework of the Horizon 2020 DESOLINATION (DEmonstration of concentrated SOLar power coupled wIth advaNced desAlinaTion system in the gulf regION) project, CO2-based mixtures will be used as the working fluid of the power cycle coupled with the desalination plant. Desalination technologies require temperatures above 50℃, therefore a fluid with a critical temperature above 70 ℃ is required to perform the compression step in the liquid phase, minimizing compression work and increasing cycle efficiency. Blending CO2 with other fluids, such as SO2, leads to an increase in the critical temperature of the mixture and makes it suitable for transcritical cycles in concentrated solar power applications, while preserving the advantages of pure CO2 over steam cycles. Throughout the DESOLINATION project, CO2 blends will be tested in the LUTsCO2 test loop to provide validation data for the design of heat exchangers. In this work, the adaptation of the test loop to the CO2 blend is investigated. A dynamic model of the test loop is built in MATLAB-Simulink, which allows each component to be modeled independently and to realize a closed-loop cycle model coupled with a controller and real gas property tables. Steady-state simulations of the system are performed and the dynamic model of each component is verified with the design values. As a result, the study highlights the key performance and fluid dynamic differences which arise from the use of a CO2 blend instead of pure CO2.

Keywords:

  • CO2 mixtures
  • Transcritical refrigeration cycle
  • Dynamic model
  • Simulink
Authors:

Giuseppe Petruccelli
Lappeenranta-Lahti University of Technology LUT, Lappeenranta, Finland

Teemu Turunen-Saaresti
Lappeenranta-Lahti University of Technology LUT, Lappeenranta, Finland

Aki Grönman
Lappeenranta-Lahti University of Technology LUT, Lappeenranta, Finland

Afonso Lugo
Lappeenranta-Lahti University of Technology LUT, Lappeenranta, Finland