SolarPACES 2020: SCARABEUS listed as one of the flagship R&D projects in Europe by Prof. Julián Blanco, Managing Director of the Solar Platform in Almería (PSA-CIEMAT)



This year, most conferences have made the decision to go virtual in order to circumvent the limitations on mobility brought about by COVID-19. SolarPACES has been no different in this regard but the


Wednesday’s plenary session, chaired by Ana María Ruiz Frías (Solar Committee Chile), focused on CSP Technology Innovation. All continents were represented by high-level speakers -Australia, Asia, America and China- who introduced their vision about research priorities in Concentrating Solar Power and the tools and funding schemes to enable their accomplishment.


In this session, Europe was represented by Prof. Julián Blanco, Director of Plataforma Solar de Almería (CIEMAT), largest research, development and test centre in Europe for Concentrating Solar technologies. Prof. Blanco’s presentation provided an excellent summary of the current research priorities identified by the European Commission, along with a very informative review of the ongoing research activities and flagship projects in Europe. With the aim to make the presentation comprehensive, the contents were broken down into twelve R&I areas approved by the Steering Group of the Solar Energy Technology (SET) Plan in 2017.


The SCARABEUS consortium is grateful to Prof. Julián Blanco for making the presentation available for download (link).

The Institute for Energy Systems and Thermodynamics at TU Wien getting ready for the testing campaign

During the last months, IET concentrated on design tasks according to work package 4, where pre-tests for the design of the air-cooled condenser (ACC) and the recuperator (printed circuit heat exchanger) are planned. Therefor several modifications of the test rig are necessary, see Figure 1:



Figure 1: Modifications of test rig at IET. Grey: additional heat exchangers (precooler and test tube). Blue: cooling water lines.


With the combination precooler and test-test-tubes, desuperheating and condensation experiments at a pressure level of p = 66 bar are planned. For pure CO2 the corresponding condensation temperature is 26,11 °C. Maximum CO2-temperature will be 180 °C, so different desuperheating / condensation tests are possible depending on entrance temperature of CO2 and cooling load of the precooler. In the first step, experiments with pure CO2 will be done, then testing with blended CO2 by adding a refrigerant (R1234ze) will follow. Adding a blend will give a first impression of about the behaviour of a mixture instead of pure CO2 and will help to train the handling of harmless mixtures on the rig, in the perspective of the future planned tests with other blends being developed and tested at UBS and POLIMI.



Figure 2: Left: Precooler delivered from KELVION. Right: test rig under modification.



The SCARABEUS team keeps growing at University of Seville


The SCARABEUS team at University of Seville keeps growing. USE is very happy to welcome Pablo Rodríguez to support the optimization and integration tasks. Find some more information about him below and follow his activities through LinkedIn here:




Pablo Rodríguez standing in front of a Ljungström turbine at the lab


I’m Pablo Rodríguez, a Sevillian engineer recently graduated from the master’s degree in Industrial Engineering at the Escuela Técnica Superior de Ingeniería (University of Seville). Specialised in Energy Engineering, I’m keen on topics such as energy efficiency, process optimization, power generation, renewable energies, SWRO plants or refrigeration. It’s in the latter of these subjects that I wrote my BSc and MSc theses: performing an analysis about the international regulations of refrigerants (anybody sees the link to some of the dopants used in SCARABEUS?).


I just joined the Thermal Power Group (Department of Energy Engineering, University of Seville) as a researcher. I’m sincerely enthusiastic about being part of the SCARABEUS project, in which I promised to put all my commitment and energy to achieve the best results.


Recuperator Model with design process using pure CO2

The SCARABEUS concept relies on a recuperative cycle using supercritical carbon dioxide as working fluid. Being supercritical and in order to achieve high efficiency, very high pressures and temperatures are involved and a recuperator becomes mandatory. This is a device which can improve the thermodynamic cycle efficiency by cooling the sCO2 after its expansion and heating it after its compression, without any additional heat exchange with the environment.


3D model of the recuperator to be installed in the test rig at TUW


The advantage to use printed circuit heat exchanger technology in the recuperator is to withstand high pressure and high temperature with reduced footprint (large area-to-volume ratio). This is why PCHE is the technology of choice in SCARABEUS. The 3D model above represents the recuperator which will be installed in the test rig at TUW. It is designed for a pressure of 220 bar and a temperature of 650°C and the geometry of the internal channel configuration is shown below.



Internal channels of the PCHE developed by KELVION for SCARABEUS


Some CFD calculations will be performed to study new types of internal geometries in order to optimize the thermal-hydraulical performances and to decrease heat exchange area. While this technology is already very compact, the Company is pursuing further reductions of footprint.

Researchers from City pass milestone on the route to PhD

Researchers from City pass milestone on the route to PhD


This week two researchers from the SCARABEUS research team at City, University of London, successfully completed their transfer from MPhil to PhD. This milestone, which has been completed just over a year since beginning at City, marks the successful transition from registration as a Master of Philosophy (MPhil) student to a full PhD candidate.


For the transfer, Mr Omar Aqel and Ms Salma Salah both prepared a technical report containing a literature review and an update on their work to date, and presented a 30-minute presentation over Microsoft Teams, followed by Q&A, to an internal audience of academics and researchers from City.


Mr Omar Aqel presented his report entitled “Optimization of cycle and turbine design for small-scale solar power plants employing CO2-based working fluids”. Within Omar’s work he has investigated the effect of candidate dopants on optimal cycle conditions within CSP applications, with a particular focus on the expansion process. Results highlighted the change in working fluid properties such as molecular weight, speed of sound, density, and the adiabatic coefficient. Having also explored the sensitivity of turbine design to dopant type and amount, Omar will now focus on the application of CO2-based working fluids in small-scale power plants. He aims to investigate their feasibility using an integrated system approach which accounts for turbomachinery design restrictions that are unique to small-scale installations.




Ms Salma Salah presented her report entitled “Advanced design optimisation methods for supercritical CO2 multi-stage axial turbines”. Within Salma’s work she discussed the various aspects of axial turbine design including design methodology, previous preliminary and computational fluid dynamic (CFD) studies on sCO2 turbines, in addition to existing prototypes and conceptual designs for sCO2 turbomachinery. In this work, 100 kW and 100 MW design models have been developed and a parametric study has been conducted to examine the effect of various design parameters on the performance of a small-scale sCO2 turbine. This work was concluded by detailing the future steps for her research.



New Open Access publication by University o Brescia and Politecnico di Milano provides information about characterisation of supercritical CO 2 blends

In the last Open Access paper published by UNIBS and POLIMI, a new methodology for
the thermal stability test of CO2 blends have been developed and tested.
The method proposed relies on the study of the thermodynamic behaviour of the
working fluid from the variation of the van der Waals coefficients. The comparison of
the estimated coefficients a, b and the molar mass (MM) from the regression of the
experimental data (in the gas phase), starting from the virgin fluid isochoric line, and
after different thermal stress test, can be representative of potential decomposition of
the investigated fluid. As a consequence of the thermal stress, the substance
decomposes in a mixture of different unknown species that, for simplicity, is assumed
as a pure fluid characterised by different coefficients a, b and MM. Moreover, starting
from the obtained parameters, the isothermal compressibility k T can be used as a
proper index to highlight the impact of the thermal degradation on the power cycle.

An example of the new method is briefly discussed for a mixture of carbon dioxide and
perfluorohexane, with molar fractions of 80% and 20% respectively. In Figure 1 , the
virgin fluid measurements are along mixture density value of 99.4 kg/m 3 , in the gas
phase, while measured p-T points after each thermal stress are represented. The best
fit of the experimental values, using the van der Waals equation of state, yields the
values in Table 1 , assuming a pure fluid behaviour of the mixture, while Table 2 shows
the resulting isothermal compressibility k T at different temperatures. Since
measurements at 250°C and 300°C are in agreement with the fresh mixture, the values
were included for the calculation of the virgin mixture parameters.
Although the van der Waals parameters are slightly different after the thermal stress
tests at 350°C and 400°C, the mixture can be considered thermally stable up to 400°C:
this behaviour is also confirmed by the parameter k T . Decomposition phenomena occur
from 450°C where not only the isothermal compressibility increases by more than 50%
with respect to the virgin mixture but also a strong deviation of the van der Waals
parameters from initial values can be observed



Figure 1 Results of P-T measurements for the mixture CO 2 +C6F 14 .

Table 1 Parameters a, b and MM of the van der Waals equation of state of the mixture carbon dioxide and perfluorohexane.







Virgin mixture 0.818 0.086 102.4
350°C 0.901 0.087 102.9
400°C 0.924 0.088 101.0
450°C 0.016 0.360 158.7
500°C 0.004 0.584 176.1


Table 2 The estimated isothermal compressibility kT of carbon dioxide and perfluorohexane at 120°C for the virgin and the decomposed mixture using the van der Waals coefficients and MM of Table 4.





Virgin mixture 2.246 0.052
350°C 2.084 0.054
400°C 2.072 0.057
450°C 3.435 0.122
500°C 4.149 0.247


PS: For more information, follow this link to the online article: link.

Hydraulic testing of heat exchangers tube completed at Kelvion

With a few weeks of delay due to the COVID-19 outbreak, the tubes used to determine the heat transfer coefficient to design the Air-Cooled Condenser have successfully undergone hydrostatic testing at KELVION. They will soon be installed in the test rig at TUW.

Watch out for the upcoming Call for Papers for the 4th European sCO2 conference in Prague (March 2021)

The 4th European sCO2 Conference in 2021 focusses on supercritical carbon dioxide for energy systems. Scientists and researchers from academia and industry as well as end users are kindly invited to share and discuss the latest outcomes from their sCO2 related projects. Moreover, this conference is the perfect place to establish new initiatives and cooperations amongst those who are active in this fascinating field of research.


Conference Topics:

  • Heat Exchanger
  • Turbomachines and Cycles
  • sCO2 Applications and Energy Systems
  • sCO2 Experiments and Loops
  • Fluid and Material Aspects


In case of any questions please contact

2 nd Progress Meeting completed successfully on April 22 nd and 23 rd

The 2nd Progress Meeting of SCARABEUS, hosted by University of Seville (Spain) and due to take place on April 22nd and 23rd, was held on-line on the same dates. Due to the limitations brought about by COVID-19, the meeting could not be developed face-to-face, as planned, but the commitment and hard work of all partners enabled a successful meeting with exactly the same Agenda as scheduled originally.

Over twenty five researchers from partners across Europe joined the two-day meeting and engaged in thrilling technical discussion about the progress made in the first year of the project. It was confirmed that SCARABEUS is developing according to schedule, with minor delays and certainly no impacts on the scope of work. Renewed commitment and a number of ideas for the continuous adaption to the new, unforeseen situation were put forward to ensure that all partners keep up with the good work carried out in the first twelve months.

Cancellation of the dissemination event jointly organized by SCARABEUS and SOCRATCES at University of Seville. The event was originally scheduled for April 22nd

Cancellation of the dissemination event jointly organized by SCARABEUS and SOCRATCES at University of Seville. The event was originally scheduled for April 22nd


Due to the recent recommendations provided by the Government of Spain and the subsequent measures adopted by University of Seville, the Networking Session on key enabling Concentrated Solar Power technologies scheduled for April 22nd at the School of Engineering of this institution has been cancelled.


The event will be organised again in the future, once the said measures will be lifted. Further information will be announced on the website and through LinkedIn when available.


The SCARABEUS and SOCRATCES consortia would like to apologise for any inconvenience this cancellation may cause.