Recuperator Model with design process using pure CO2

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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

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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

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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.

a

(MPam6kmol-2)

 b

(m3kmol-1)

 MM

(kgkmol-1)
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.

1/kT

(MPa)

 u(kT)

(MPa)
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

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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)

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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 sCO2@uni-due.de

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

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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

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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.

 

Cerro Dominador, the first solar thermal tower plant in Latin America, raises its receiver at 220 meters high

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  • This is one of the last milestones in the construction of the project executed by Abengoa and Acciona in the Atacama Desert (Chile) and owned by EIG Global Energy Partners.
  • Weighing 2,300 tons, this highly complex piece will concentrate the solar radiation reflected from the 10,600 heliostats that surround the tower.
  • This is the first time this maneuver has been carried out in this kind of project worldwide.

March 5th, 2020. The Cerro Dominador solar thermal project, owned by EIG Global Energy Partners and built by Abengoa and Acciona in the Atacama Desert in Chile, has just achieved one of the key milestones of tis development before its entry into operation: the raising and installation of its solar receiver at 220 meters high. It was placed in the highest part of the central tower of the complex, which is surrounded by 10,600 heliostats.

The maneuver was completed in recent weeks, with the positioning of the receiver (piece of high complexity weighing 2,300 tons) in the foundation octagon, at 220 meters high in the central tower of the solar thermal plant. The function of the receiver is to concentrate the solar radiation reflected from the heliostats that are located around the 250-meter tower and heat the salts that will be stored to generate electricity.

The complete raising operation lasted a week, since the moment the receiver entered a cavity located at the base of the tower. Once inside, the receiver was raised to the top of the construction with 16 hydraulic industrial jacks. The ascent rate did not exceed five meters per hour, due to safety requirements and given the technical complexity of the entire procedure.

“We are very proud to have achieved this milestone. We continue advancing without pause in the construction of this iconic project for the region,” said Fernando González, CEO of Cerro Dominador.

 

“This is the first time this maneuver has been carried out worldwide in this type of project,” as explained by Abengoa’s project manager on Cerro Dominador, Héctor Berlangieri, who also pointed out that the conceptual idea of the operation and the engineering came from the Spanish company.

On the other hand, Luis Pérez, site manager of Acciona in the project, explained the great technical complexity of this raising maneuver: “A total control is needed on the ascent rate of the receiver, limited to approximately six meters per hour. We are really proud to participate in such a unique project and the commitment we are all demonstrating to make it happen.”

 

Find out more in this Youtube video: link.

 

About Abengoa

Abengoa (MCE: ABG/P:SM) applies innovative technology solutions for sustainability in the infrastructures, energy and water sectors. (www.abengoa.com)

 

Francesco Crespi takes PhD viva with honours

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Francesco Crespi takes PhD viva with honours

 

Francesco Crespi took his PhD examination at University of Seville on Tuesday February 12th 2020. A commission comprised of five leading researchers in the area of Concentrated Solar Power acknowledged the valuable contribution of Francesco’s work and his capacity to approach the topic from an innovative perspective. If you would like to get a free copy of the PhD dissertation, follow this LINK

Fortunately enough, Francesco will join the SCARABEUS team at University of Seville in the following days. Welcome.

SCARABEUS research team at City, University of London fully assembled

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This month the latest and final member of the SCARABEUS research team at City joined the group and began his PhD.

 

In total, the research team at City comprises of Prof Abdulnaser Sayma (Principal investigator at City), Dr Martin White (Co-investigator), Dr Mahmoud Khader (Research Associate) and three PhD students, Mr Omar Aqel, Ms Salma Salah and Mr Abdel-Rahman Abdeldayem.

 

City are leaders of work package 3 (Turbomachinery) and are working with the industrial partner Exergy to deliver the design of the turbomachinery components for the SCARABEUS plant.

 

The latest recruit will join the two PhD students who were recruited in the second half of 2019 and are already in the early stages of their research. The three PhD students will be conducting research into important aspects related to turbomachinery design for supercritical power cycles operating with CO2-blends.

 

Mr Omar Aqel will be exploring optimal cycle configurations for supercritical power cycles operating with CO2-blends, including the integration of turbomachinery design methods with cycle simulation and optimisation to enable the simultaneous optimisation of cycle layout, operating conditions and turbine design.

 

Ms Salma Salah will be investigating design and optimisation methods for multi-stage axial turbines for large-scale supercritical power cycles, and their application to the SCARABEUS plant, focussing on mean-line design and 3D shape optimisation methods.

 

Mr Abdel-Rahman Abdeldayem will be investigating loss mechanisms within multi-stage axial turbines for large-scale supercritical power cycles, and characterising the effects of the fluid blend on turbomachinery performance.

 

From left to right: Ms Salma Salah, Mr Omar Aqel, Prof Abdulnaser Sayma, Dr Martin White, Mr Abdel-Rahman Abdeldayem