Karellas, Sotirios, Prof. Dr.-Ing.

Office Hours

by appointment

Tasks

• Lecture: Renewable Energy Technology I (Part 2: Energy from Biomass)
• Lecture: Renewable Energy Technology II (Part 6: Solar Thermal Energy)

Main Focus

• Central and decentralized Energy systems
• Energy production from biomass and waste
• Renewable Energy systems
• Combined Heat, Power and cooling technology
• Energy Storage
• Hydrogen Energy

Job-related Activities

• Since 2011 Professor at the National Technical University of Athens (NTUA)
• Since 2019 Director of the Laboratory of Thermal Processes (NTUA)
• Since 2024 Task force leader of the group Hydrogen End uses of the European Hydrogen Sustainability and Circularity Panel (EHS&CP), of the Clean Hydrogen Partnership
• Since 2021 Project coordinator at the “Energy Competence Center”
• 2014 - 2021 Member of the Greek Delegation of the Energy Committee of Horizon2020  
• 2014 -2019 Member of the Greek Delegation of COSCO (Coal and Steel Committee)
• Since 2012 Member of the Combined Heat and Power “Certification body” of NTUA
• Since 2008 Consultant and provision of “Third Party Services” in Power Plants
• 2007-2008 Consultant at the “National Energy Strategy Chamber of Greece”
• 2005-2006 Engineer at Alstom Power Boiler GmbH 

Further information

Profile NTUA

Publications (Last 4 years)

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Publications (last 4 years) 

A) Books:

[A1] Heat Transfer (From Physics to Mechanical Engineering) (In Greek)

S. Karellas, E. Kakaras, T. C. Roumpedakis

Tsotras 2022, ISBN 975-618-5495-98-5

 

B) Chapters in Books:

[B1] Numerical methods for solid-liquid phase-change problems

M. Zeneli, A. Nikolopoulos, S. Karellas, N. Nikolopoulos

Chapter in ultra-high temperature thermal energy storage, transfer and conversion, Editor: Alejandro Datas, Academic Press (Elsevier) 2020, ISBN 9780128199558

[B2] Organic Rankine Cycle systems for waste heat recovery in thermal power plants 

 

K. Braimakis, S. Karellas

Chapter in Small Scale Power Generation Handbook, Series: Heat Transfer, Series Editors: Umberto Desideri, Lorenzo Ferrari, Academic Press (Elsevier) 2021, ISBN 9780128216729

 

[B3] Microbial CO2 Conversion Routes

D. Magiri-Skouloudi, E. Topakas, S. Karellas

Chapter in Green Chemistry Series No. 74, Chemical Valorisation of Carbon Dioxide

Editors: Georgios Stefanidis and Andrzej Stankiewicz, The Royal Society of Chemistry 2023 Published by the Royal Society of Chemistry, www.rsc.org, 2023, ISBN-10: 1839164077. ISBN-13: 978-1839164071

 

 

C) Articles in Journals: 

[C1] Analysis of Alternative MSW Treatment Technologies with the Aim of Energy Recovery in the Municipality of Vari-Voula-Vouliagmeni

S. Thanopoulos, S. Karellas, M. Kavrakos, G. Konstantellos, D. Tzempelikos, D. Kourkoumpas

Waste and Biomass Valorization, Vol 11, 1585-1601, 1 April 2020

https://doi.org/10.1007/s12649-018-0388-5

 

[C2] Performance evaluation and optimization of the cooling system of a hybrid thmionic-photovoltaic converter

M. Zeneli, A. Bellucci, G. Sabbatella, D. M. Trucchi, A. Nikolopoulos, N. Nikolopoulos, S. Karellas, E. Kakaras

Energy Conversion and Management, Vol. 210, 112717, 15 April 2020

doi.org/10.1016/j.enconman.2020.112717

 

[C3] Energy-exergy analysis of ultra-supercritical biomass-fuelled steam power plants for industrial CHP, district heating and cooling

K. Braimakis, D. Magiri-Skouloudi, D. Grimekis, S. Karellas

Renewable Energy, Vol. 154, pp. 252-269, July 2020

doi.org/10.1016/j.renene.2020.02.091

 

[C4] Life cycle analysis of ZEOSOL solar cooling and heating system

T. C. Roumpedakis, G. Kallis, D. Magiri-Skouloudi, D. Grimekis, S. Karellas

Renewable Energy, Vol. 154, pp. 82-98, July 2020

https://doi.org/10.1016/j.renene.2020.02.114

 

[C5] Performance Results of a Solar Adsorption Cooling and Heating Unit

T. C. Roumpedakis, S. Vasta, A. Sapienza, G. Kallis, S. Karellas, U. Wittstadt, M. Tanne, N. Harborth, U. Sonnenfeld

Energies, 2020, 13(7), 1630; https://doi.org/10.3390/en13071630

 

[C6] Design evaluation for a finned-tube CO₂ gas cooler in residential applications

C. Alexopoulos, O. Aljolani, F. Heberle, T. C. Roumpedakis, D. Brüggemann, S. Karellas

Energies, 2020, 13(10), 2428; https://doi.org/10.3390/en13102428

 

[C7] Exergetic analysis of CO₂ and ultra-low GWP refrigerant mixtures as working fluid in ORC for waste heat recovery

K. Braimakis, A. Mikelis, A. Charalampidis, S. Karellas

Energy, Vol. 203 (10), 117801, July 2020; https://doi.org/10.1016/j.energy.2020.117801

 

[C8] The Biofficiency Project Part 2: A blueprint design for the next generation of biomass-fired cogeneration plants

T. de Riese, L. Hansen, D. Magiri-Skouloudi, K. Braimakis, L. Clemens, C. Bergins, S. Fendt, S. Karellas, H. Spliethoff

VGB Powertech, Vol. 8, 2020

 

[C9] Dynamic modelling of an ultra high temperature PCM with combined heat and electricity production for application at residential buildings

I. Violidakis, N. Zeneli, K. Atsonios, G. Strotos, N. Nikolopoulos, S. Karellas

Energy and Buildings, Vol. 222 (10), 110067, September 2020; https://doi.org/10.1016/j.enbuild.2020.110067

 

[C10] Exergetic and economic analysis of a solar driven small scale ORC

T. C. Roumpedakis, G. Loumparidis, E. Monokrousou, K. Braimakis, A. Charalampidis, S. Karellas

Renewable Energy, Vol. 157, pp. 1008-1024, September 2020; https://doi.org/10.1016/j.renene.2020.05.016

 

[C11] Modelling of methanol production via combined gasification and power to fuel

E. I. Koytsoumpa, S. Karellas, E. Kakaras

Renewable Energy, Vol. 158, pp. 598-611, October 2020; https://doi.org/10.1016/j.renene.2020.05.169

 

[C12] Energy assessment based on semi-dynamic modelling of a photovoltaic driven vapour compression chiller using phase change materials for cold energy storage

E. Varvagiannis, A. Charalampidis, G. Zsembinski, S. Karellas, L.F. Cabeza

Renewable Energy, Vol. 163, pp. 198-212, January 2021; https://doi.org/10.1016/j.renene.2020.08.034

 

[C13] Introducing an artificial neural network energy minimization multi-scale drag scheme for fluidized particles

A. Nikolopoulos, C. Samlis, M. Zeneli, N. Nikolopoulos, S. Karellas, P. Grammelis

Chemical Engineering Science, Vol. 229, 116013, January 2021; https://doi.org/10.1016/j.ces.2020.116013

 

[C14] Thermodynamic and techno-economic assessment of pure and zeotropic fluid ORCs for waste heat recovery in a biomass IFCC plant

S. Georgousopoulos, K. Braimakis, D. Grimekis, S. Karellas

Applied Thermal Engineering, Vol. 183, 116202, January 2021; https://doi.org/10.1016/j.applthermaleng.2020.116202

 

[C15] An innovative solar-biomass energy system to increase the share of renewables in office buildings

V. Palomba, E. Borri, A. Charalampidis, A. Frazzica, S. Karellas, L.F. Cabeza

Energies, Vol. 4, Issue 4, February 2021, https://doi.org/10.3390/en14040914

 

[C16] Exergetic efficiency potential of double-stage ORCs with zeotropic mixtures of natural hydrocarbons and CO₂

K. Braimakis, V. Grispos, S. Karellas

Energy, Vol. 218, March 2021, https://doi.org/10.1016/j.energy.2020.119577

 

[C17] Hybrid cascade heat pump and thermal-electric energy storage system for residential buildings: Experimental testing and performance analysis

V. Palomba, A. Bonanno, G. Brunaccicni, D. Aloisio, F. Sergi, G.E. Dino, E. Varvagiannis, S. Karellas, B. Nitsch, A. Strehow, A. Grobetae, R. Herrmann

Energies, Vol. 14, Issue 9, May 2021, https://doi.org/10.3390/en14092580

 

[C18] Life cycle analysis of a photovoltaic driven reversible heat pump

C. Riva, T. C. Roumpedakis, G. Kallis, M.V. Rocco, S. Karellas

Energy and Buildings, Vol. 240, June 2021, https://doi.org/10.1016/j.enbuild.2021.110894

 

[C19] Development, experimental testing and techno-economic assessment of a fully automated marine Organic Rankine Cycle prototype for jacket cooling water heat recovery

P. Pallis, E. Varvagiannis, K. Braimakis, T. Roumpedakis, A.-D. Leontaritis, S. Karellas

Energy, Vol. 228, August 2021, https://doi.org/10.1016/j.energy.2021.120596

 

[C20] Development, experimental testing and techno-economic assessment of a fully automated marine Organic Rankine Cycle prototype for jacket cooling water heat recovery

P. Pallis, E. Varvagiannis, K. Braimakis, T. Roumpedakis, A.-D. Leontaritis, S. Karellas

Energy, Vol. 228, August 2021, https://doi.org/10.1016/j.energy.2021.120596

[C21] Techno-economic assessment of a small-scale biomass ORC-CHP for district heating

K. Braimakis, A. Charalampidis, S. Karellas

Energy Conversion and Management, Vol. 2471 November 2021, https://doi.org/10.1016/j.enconman.2021.114705

 

[C22] Bioenergy with carbon capture and utilization: A review on the potential deployment towards a European circular bioeconomy

E. I. Koytsoumpa, D. Magiri-Skouloudi, S. Karellas, E. Kakaras

Renewable and Sustainable Energy Reviews, Vol 152 December 2021, https://doi.org/10.1016/j.rser.2021.111641

 

[C23] Energy and economic performance assessment of efficiency measures in zero-energy office buildings in Greece

P. Pallis, K. Braimakis, T. Roumpedakis, E. Varvagianis, S. Karellas, L. Doulos, M. Katsaros, P. Vourliotis

Building and Environment, Vol. 206, December 2021, https://doi.org/10.1016/j.buildenv.2021.108378

 

[C24] Organic flash cycles in Rankine-based Carnot batteries with large storage temperature spreads

M. Weitzer, D. Müller, D. Steger, A. Charalampidis, S. Karellas, J. Karl

Energy Conversion and Management, Vol 2551 March 2022, https://doi.org/10.1016/j.enconman.2022.115323

 

[C25] Techno-economic assessment of dimethul carbonate production based on carbon capture and utilization and power-to-fuel technology

V. Kontou, D. Grimekis, K. Braimakis, S. Karellas

Renewable and Sustainable Energy Reviews, Vol. 157, April 2022, https://doi.org/10.1016/j.rser.2021.112006

 

[D26] Techno-economic evaluation of medium scale power to hydrogen to combined heat and power generation systems

N. Skordoulias, E.-I. Koytsoumpa, S. Karellas

International Journal of Hydrogen Energy, Vol. 47, 63, July 2022, https://doi.org/10.1016/j.ijhydene.2022.06.057

 

[C27] Life cycle analysis of a waste heat recovery for marine engines Organic Rankine Cycle

G. Kallis, T.C. Roumpedakis, P. Pallis, Z. Koutantzi, A. Charalampidis, S. Karellas

Energy, Volume 25715 October 2022, https://doi.org/10.1016/j.energy.2022.124698

 

[C28] Exergy efficiency potential of dual-phase expansion trilateral and partial evaporation ORC with zeotropic mixtures

K. Braimakis, S. Karellas

Energy, Vol. 2621 January 2023, https://doi.org/10.1016/j.energy.2022.125475

 

[C29] Smart maintenance with regression analysis for efficiency improvement in photovoltaic energy systems

I. Ay, M. Kademli, S. Savas, S. Karellas, A. Markopoulos, Ch.-S. Hatzilau, P. Denvil, H. Dusbudak, A. S. Arslan, M. Koc, K. Duraklar, K. Sunal

Journal of Solar Energy Research, Vol. 8, Issue 5, Pages 1663-1679, 2023

 

[C30] Numerical and Experimental Analysis of a Low-GWP Heat Pump Coupled to Electrical and Thermal Energy Storage to Increase the Share of Renewables across Europe

O. A. Rehman, V. Palomba, A. Frazzica, A. Charalampidis, S. Karellas, L. F. Cabeza

Sustainability, Vol. 15, Issue 6, March 2023, https://doi.org/10.3390/su15064973

 

[C31] Comparative life cycle greenhouse gas emissions assessment of battery energy storage technologies for grid applications

X. Han, Y. Li, L. Nie, X. Huang, Y. Dengm J. Yan, D.-S. Kourkoumpas, S. Karellas

Journal of Cleaner Production, Vol 392, 15 March 2023, DOI: 10.1016/j.jclepro.2023.136251

 

[C32] Tracking the life-cycle greenhouse gas emissions of municipal solid waste incineration power plant: A case study in Shanghai

X. Han, H. Chang, C. Wang, J. Tai, S. Karellas, J. Yan, L. Song, Z. Bi

Journal of Cleaner Production, Vol 398, 20 April 2023, DOI: 10.1016/j.jclepro.2023.136635

 

[C33] Innovations for organic Rankine cycle power systems: Current trends and future perspectives

C. Wieland, C. Schifflechner, K. Braimakis, F. Kaufmann, F. Dawo, S. Karellas, G. Besagni, C. N. Markides

Applied Thermal Engineering, Vol 225, 5 May 2023, DOI: 10.1016/j.applthermaleng.2023.120201

 

[C34] CFD modelling of an indirectly heated calciner reactor, utilized for CO₂ capture, in an Eulerian framework

G. Kanellis, M. Zeneli, N. Nikolopoulos, C. Hofmann, J. Stöhle, S. Karellas, J. Konttinen

Fuel, Vol 346, 15 August 2023, DOI: 10.1016/j.fuel.2023.128251

[J113] An innovative heating, ventilation, air conditioning and refrigeration circular economy system for reducing carbon dioxide emissions in Europe via extensive reuse of existing fluorinated gases

N. Barmparitsas, S. Karellas, P. Pallis, S. Thanopoulos, D. Kobelt

Energies, Vol. 16, Issue 23, December 2023, DOI: 10.3390/en16237705

 

[C35] Simplified Modeling and Experimental Validation of a Combi-Storage Distribution Tank for Seasonal Thermal Energy Storage Systems

T. C. Roumpedakis, A.-D. Leontaritis, P. Vlachogiannis, E. Varvagiannis, A. Charalampidis, S. Karellas

Thermo, Vol. 3, Issue 4, pages 657 – 681, December 2023, DOI: 10.3390/thermo3040038

 

[C36] Life Cycle assessment of novel thermochemical – biochemical biomass-to-liquid pathways for sustainable aviation and maritime fuel production

D.-S. Kourkoumpas, A. Bon, A. Sagani, K. Atsonios, P. Grammelis, S. Karellas, E. Kakaras

Bioresources Technology, Vol 393, Febr 2024, DOI: 10.1016/j.biortech.2023.130115

 

[C37] A review of alternative processes for green hydrogen production focused on generating hydrogen from biomass

A.-P. Damiri, E. Stamatakis, S. Bellas, M. Zoulias, G. Mitkidis, A.G. Anastasiadis, S. Karellas, G. Tzamalis, A. Stubos, T. Tsoutsos

Hydrogen, Vol. 5, Issue 2, Pages 163 – 184, June 2024, DOI: 10.3390/hydrogen5020011

 

[C38] Cost-Optimality Assessment of a Solar Trigeneration System for Tertiary Sector Buildings in Greece

D. Tziritas, K. Braimakis, D. Bakirtzis, G. M. Stavrakakis, S. Yfanti, K. Terzis, P. Langouranis, P. L. Zervas, S. Karellas

Energies, Vol. 17, Issues 12, June 2024, DOI: 10.3390/en17122819

 

[C39] Life Cycle assessment of an innovative alcohol-to-ject process: The case for retrofitting a bioethanol plant for sustainable aviation fuel production

D.-S. Kourkoumpas, A. Sagani, A. Hull, A. Hull, S. Karellas, P. Grammelis

Renewable Energy, Vol. 228, July 2024, DOI: 10.1016/j.renene.2024.120512

 

[C40] Life cycle environmental hotspots analysis of typical electrochemical, mechanical and electrical energy storage technologies for different application scenarios: Case study in China

Y. Li., X. Han, L. Nie, Y. Deng, J. Yan, T.C. Roumpedakis, D.-S. Kourkoumpas, S. Karellas

Journal of Cleaner Production, Vol. 466, 10 August 2024, DOI: 10.1016/j.jclepro.2024.142862

 

[C41] Innovative waste heat valorisation technologies for zero-carbon ships − A review

R. Fisher, L. Ciappi, P. Niknam, K. Braimakis, S. Karellas, A. Frazzica, A. Sciacovelli

Applied Thermal Engineering, Vol 253, 15 September 2024, DOI: 10.1016/j.applthermaleng.2024.123740

 

[C42] Thermodynamic investigation of integrated organic Rankine cycle-ejector vapor compression cooling cycle waste heat recovery configurations for cooling, heating and power production

K. Braimakis, S. Karellas

Energy, Vol304, 30 September 2024, DOI: 10.1016/j.energy.2024.132020

 

[C44] Transforming CO₂ into Synthetic Fuels: Modeling, Simulation, and Optimization Analysis of Methanol Production from Industrial Wastes

V. Kontou, A. Peppas, S. Kottaridis, C. Politi, S. Karellas

Eng, Vol5. Issue 3, September 2024, DOI: 10.3390/eng5030070

 

[C45] A novel dual-stage intercooled and recuperative gas turbine system integrated with transcritical organic Rankine cycle: System modeling, energy and exergy analyses

X. Han, Y. Dai, X. Guo, K. Braimakis, S. Karellas, J. Yan

Energy, Vol 305, 1 October 2024, DOI: 10.1016/j.energy.2024.132252