Concept Note

Concept note
1. Title
Modelling and Experimental Validation of the Operating Behavior of sCO2 Power Processes in
Thermal Energy Storage Systems
2. Abstract
The main aim of this research is Modelling and Experimental Validation of the Operating Behavior
of sCO2 Power Processes in Thermal Energy Storage Systems. CO2 is an environmentally friendly
heat transfer fluid and has many advantages in thermal energy and power systems due to its
peculiar thermal transport and physical properties. Supercritical CO2 (S-CO2) thermal energy
conversion systems are promising for innovative technology in domestic and industrial
applications including heat pump, air-conditioning, power generation, renewable energy systems,
energy storage, thermal management, waste heat recovery and others. High supercritical CO2
turbine inlet temperature can be achieved, avoiding the temperature limitations set by the use of
solar molten salts as primary heat transfer fluid. The packed bed thermal energy storage enables
the decoupling between solar irradiation collection and electricity production, and it grants
operational flexibility while enhancing the plant capacity factor.
3. Background to the Study

Increased concentration of anthropogenic CO2 in the atmosphere due to fossil fuel combustion is
widely believed to be responsible for global warming and extreme climate change. In particular,
industrial processes are energy intensive, up to 70% of the energy is provided by fossil fuel and
about 40% of global CO2 emissions are attributable to the industrial sector(This, Attribution-
noncommercial-noderivs, By-nc-nd, If, & Rose, 2019).
The integration of supercritical carbon dioxide (sCO2) power cycles with thermal energy storage
(TES) systems holds great promise in enhancing the efficiency and flexibility of power generation.
This concept note proposes a comprehensive investigation into the modeling and experimental
validation of the operating behavior of supercritical carbon dioxide (sCO2) power processes
within TES systems. supercritical carbon dioxide (sCO2) power cycles have gained considerable
attention due to their high efficiency, compactness, and potential for various applications. Thermal
energy storage systems offer the ability to store excess energy and dispatch it when needed, thereby
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improving grid stability and accommodating intermittent renewable energy sources(Trevisan &
Gu, 2020)
The sCO2 power cycle is an innovative concept for converting thermal energy to electrical energy.
It uses sCO2 as the working fluid in a closed or semi-closed Brayton cycle. These power cycles
have several potential benefits, such as high efficiency, small equipment size and plant footprint
(and therefore lower capital cost), and the potential for full carbon capture(Zhu, 2017).
CO2 thermal energy conversion systems are promising technology in many applications in power
generation with conventional and renewable energy sources, energy storage and waste heat
recovery. Both supercritical and transcritical CO2 thermal systems are efficient energy
conversion and utilization technology(Cheng & Xia, 2023).
4. Objectives of the Study

4.1. General objective
The main objective of the research is Modelling and Experimental Validation of the Operating
Behavior of sCO2 Power Processes in Thermal Energy Storage Systems
4.2. Specific objectives

➢ To Develop a detailed mathematical model of sCO2 power processes integrated with TES
systems, considering transient behavior and dynamic interactions
➢ To Conduct experimental validation to verify the accuracy and reliability of the developed
model under various operating conditions
➢ To Investigate the performance, efficiency, and dynamic response of sCO2 power cycles
with TES integration through simulations and experiments
➢ To Identify key parameters and operating strategies to optimize the performance and
flexibility of the integrated system
5. Expected Outcomes
➢ validated mathematical model capable of accurately predicting the operating behavior of
sCO2 power cycles integrated with TES systems
➢ Insights into the performance and dynamic response of the integrated system, facilitating
the optimization of operational strategies and component design
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➢ Identification of key parameters and control strategies to enhance the efficiency, flexibility,
and reliability of sCO2-based power generation with thermal energy storage
6. Significance
➢ The proposed research contributes to the advancement of sustainable power generation
technologies by providing a comprehensive understanding of the synergies between
sCO2 power cycles and thermal energy storage systems
➢ The findings can inform the design and deployment of integrated sCO2-TES systems
for various applications, including renewable energy integration, grid stabilization, and
industrial processes
➢ The developed models and insights can guide future research and development efforts
aimed at further improving the performance and scalability of sCO2-based power
generation technologies
7. Proposed Research Design, Methods/Procedures

The proposed research design and methods/procedures would depend greatly on the specific
research question or objective being addressed. However, here is a general outline of how one
might structure a research design and methodology.
7.1. Mathematical Modeling

➢ Utilize thermodynamic principles to develop a dynamic model of sCO2 power cycles,
including compressors, turbines, heat exchangers, and storage tanks
➢ Incorporate the thermophysical properties of carbon dioxide in supercritical state for
accurate prediction of system behavior
➢ Extend the model to account for the interaction between the sCO2 power cycle and the
thermal energy storage system, considering heat transfer processes and storage dynamics
7.2. Experimental Validation

➢ Design and construct a laboratory-scale sCO2 power system integrated with a TES
unit
➢ Perform a series of experiments to measure the system's performance, including
efficiency, power output, temperature profiles, and response to load variations
➢ Compare experimental results with simulation predictions to validate the accuracy
of the developed model
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7.3. Performance Analysis
Utilize the validated model to analyze the transient behavior and dynamic response of the
integrated sCO2 power cycle with TES
Investigate the influence of key parameters such as operating temperature, pressure, and
storage capacity on system performance and efficiency
Explore different control strategies to optimize the operation of the integrated system under
varying load and renewable energy input conditions
8. Conclusion
The proposed research aims to bridge the gap between theoretical modeling and experimental
validation of sCO2 power cycles integrated with thermal energy storage systems. By elucidating
the dynamic behavior and performance characteristics of the integrated system, this study seeks to
facilitate the deployment of efficient, flexible, and sustainable power generation solutions for a
diverse range of applications. The steady state thermodynamic analysis at design point conditions
of the proposed single- recuperator recompression sCO2 cycle predicted a thermal efficiency of
about 33% Preliminary design of the heat exchanges confirmed the efficient matching of the
temperature profile of the CO2 working fluid and the exhaust gas in the gas heater
The sCO2 cycle can potentially reach thermal efficiencies of 50% or more. The high energy density
of sCO2 means the components are small, as is the overall plant footprint. These factors coupled
with other technology attributes could potentially result in lower capital and fuel costs and
decreased GHG emissions from coal-fired power generation. Two primary sCO2 power cycle
configurations have been reviewed: an indirectly-heated closed Brayton cycle and a semi-closed,
directly-fired, oxy-combustion cycle.
The benefits of the S-CO2 thermal and power systems includes the thermal efficiency can be
increased up to 5% as compared with the steam Rankine systems, the turbomachinery can be much
smaller and the overall system size can be reduced up to ten times as compared to the conventional
steam Rankine systems, the positive potential of the air-cooled S-CO2 cycle can be adopted if the
system design becomes more sophisticated, as the minimum pressure is higher than the CO2
critical pressure, the purification system requirements are lower than those of the steam Rankine
systems and CO2 is relatively cheaper and less harmful than other working fluids when an
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appropriate ventilation system is installed to prepare for a sudden large release of CO2 from the
power conversion
9. References
Cheng, L., & Xia, G. (2023). Progress and Prospects for Research and Technology Development
of Supercritical CO 2 Thermal Conversion Systems for Power , Energy Storage , and Waste
Heat Recovery ABSTRACT. Heat Transfer Engineering, 0(0), 1–18.
https://doi.org/10.1080/01457632.2023.2282765
This, R., Attribution-noncommercial-noderivs, C. C., By-nc-nd, C. C., If, T., & Rose, W. (2019).
Dynamic Modelling and Control of Supercritical CO 2 Power Cycle Using Waste Heat from
Industrial Processes Olumide Olumayegun , Meihong Wang *.
Trevisan, S., & Gu, R. (2020). Thermo-economic optimization of an air driven supercritical CO 2
Brayton power cycle for concentrating solar power plant with packed bed thermal energy
storage Balance of Plant. 211(October), 1373–1391.
https://doi.org/10.1016/j.solener.2020.10.069
Zhu, Q. (2017). Power generation from coal using supercritical CO 2 cycle Power generation
from coal using supercritical CO 2 cycle. (December).
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3. Background to the Study

4. Objectives of the Study

4.2. Specific objectives

7. Proposed Research Design, Methods/Procedures

7.1. Mathematical Modeling

7.2. Experimental Validation

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