Karellas, Sotirios, Prof. Dr.-Ing.

Visiting lecturer at:

Chair of Energy Systems
Boltzmannstrasse 15
85748 Garching

Email: sotokar@mail.ntua.gr

Office Hours

by appointment

Main Focus

  • Decentralized Energy Systems
  • Energy production from biomass and waste
  • Power plant technology
  • Combined Heat, Power and Cooling Technologies
  • Energy Storage

Job-related Activities

  • Since 2011 Professor at the National Technical University of Athens (NTUA)
  • Since 2014 Member of the Greek Delegation at ENERGY/Horizon2020 (Energy Expert)
  • Since 2014 Member of the Greek Delegation (Alternate Represetative of Greece) at COSCO (Coal and Steel Committee)
  • Since 2012 Member of the Combined Heat and Power Certification body of NTUA
  • Since 2008 Consultant and “Third Party Services” at 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)

A) Books:


[A1] Solar Cooling Applications S. Karellas, T. C. Roumpedakis, N. Tzouganatos, K. Braimakis Taylor and Francis 2018, ISBN 9781138060173, Series: Energy Systems

B) Chapters in books:

[Β1] Determination of Energy Efficiency of Hot Water Boilers and Calculation of Measurement Uncertainties S. Karellas, P. Vourliotis, P. Pallis, I.-A. Sofras, E. Kakaras Chapter in The Art of Measuring in Thermal Sciences, CRC Press (Taylor and Francis, Series: Heat Transfer, Series Editor: Prof Afshin Ghajar) (In Press)

[Β2] Solar Thermal Power Plants S. Karellas, T. C. Roumpedakis Chapter 7 in Solar Hydrogen Production, Processes, Systems and Technologies, F. Calise, M. Dentice D’Accadia, M. Santarelli, A. Lanzini, D. Ferrero, Academic Press (Elsevier) 2019, ISBN 9780128148532

[Β3] Hydrogen production and storage T. Roumpedakis, P. Vlavakis, K. Braimakis, D. Grimekis, S. Karellas Chapter 6 in Advances in Renewable Energy Engineering: Solar, Wind, Biomass, Hydrogen and Geothermal Energy Systems. Recent Advances in Renewable Energy Vol.3. Editors: Emmanuel D. Rogdakis, Irene P. Koronaki Bentham Books 2018, ISBN 978-1-68108-720-7

[Β4] Comparison of environmentally friendly working fluids for Organic Rankine power cycles K. Braimakis, T. C. Roumpedakis, A.-D. Leontaritis, S. Karellas Chapter 13 in Advances in Heat Transfer Fluids: from Numerical to Experimental Techniques, Taylor and Francis, CRC Press 2017, ISBN 9781498751858

[Β5] EU Emissions Trading Scheme Application in Bulgaria, Greece and Romania from 2008 to 2012 C.-S. Chatzilau, D. Giannakopoulos, S. Karellas, E. Kakaras Chapter 4 in Carbon Management, Technologies and Trends in Mediterranean Ecosystems, Editors: Sabit Erşahin, Selim Kapur, Erhan Akça, Ayten Namlı, Hakkı Emrah Erdoğan, Springer 2017, ISBN 978-3-319-45034-6

C) Articles in journals:

[C1] Thermodynamic analysis and life cycle assessment of supercritical pulverized coal-fired power plant integrated with No.0 feedwater pre-heater under partial loads X. Han, N. Chen, J. Yan, J. Liu, M. Liu, S. Karellas Journal of Cleaner Production, Vol. 233, pp. 1106-1122, 1 October 2019 doi.org/10.1016/j.jclepro.2019.06.159

[C2] Towards ΝZEB in Greece: A comparative study between cost optimality and energy efficiency for newly constructed residential buildings P. Pallis, N. Gkonis, E. Varvagiannis, K. Braimakis, S. Karellas, M. Katsaros, P. Vourliotis, D. Sarafianos Energy and Buildings, Vol. 198, pp. 115-137, September 2019 doi.org/10.1016/j.enbuild.2019.06.005

[C3] Integrated ORC-Adsorption cycle: A first and second law analysis of potential configurations T.C. Roumpedakis, T. Christou, E. Monokrousou, K. Braimakis, S. Karellas Energy, Vol. 179, pp. 46-58, July 2019 doi.org/10.1016/j.energy.2019.04.069

[C4] Analysis of energy storage systems to exploit wind energy curtailment in Crete G. Caralis, T. Christakopoulos, S. Karellas Renewable and Sustainable Energy reviews,103, 122-139, April 2019 doi.org/10.1016/j.rser.2018.12.017

[C5] Numerical simulation of a silicon-based latent heat thermal energy storage system operating at ultra-high temperatures M. Zeneli, I. Malgarinos, A. Nikolopoulos, N. Nikolopoulos, P. Grammelis, S. Karellas, E. Kakaras Applied Energy, Vol. 242, pp. 837-853, 15 May 2019 doi.org/10.1016/j.apenergy.2019.03.147

[C6] Modelling of Substitute Natural Gas production via combined gasification and power to fuel E.-I. Koytsoumpa, S. Karellas, E. Kakaras Renewable Energy, Vol. 135, pp. 1354-1370, May 2019 doi.org/10.1016/j.renene.2018.09.064

[C7] Analysis of energy storage systems to exploit wind energy curtailment in Crete G. Caralis, T. Christakopoulos, S. Karellas Renewable and Sustainable Energy reviews,103, 122-139, April 2019 doi.org/10.1016/j.rser.2018.12.017

[C8] Experimental investigation of CO2 solubility and its absorption rate into promoted aqueous potassium carbonate solutions at elevated temperatures D. Grimekis, S. Giannoulidis, K. Manou, K.D. Panopoulos, S. Karellas International Journal of Greenhouse Gas Control, Vol. 81, pp. 83-92, February 2019 doi.org/10.1016/j.ijggc.2018.12.008

[C9] Thermodynamic analysis of an improved flue gas pre-dried lignite-fired power system integrated with water recovery and drying exhaust gas recirculation X. Han, M. Liu, J. Yan, S. Karellas, J. Wang, F. Xiao Drying Technology, Taylor & Francis Online 2019 doi.org/10.1080/07373937.2019.1607871

[C10] Hybrid adsorption-compression systems for air conditioning in efficient buildings: Design through validated dynamic models V. Palomba, E. Varvagiannis, S. Karellas, A. Frazicca Energies, Vol. 12, Issue 6, 2019, Article Number 1161 doi.org/10.3390/en12061161

[C11] Cost effectiveness assessment and beyond: A study on energy efficiency interventions in Greek residential building stock P. Pallis, N. Gkonis, E. Varvagiannis, K. Braimakis, S. Karellas, M. Katsaros, P. Vourliotis Energy and Buildings, Vol. 182, pp. 1-18, January 2019 doi.org/10.1016/j.enbuild.2018.10.024

[C12] A review of key environmental and energy performance indicators for the case of renewable energy systems when integrated with storage solutions D.Kourkoumpas, G. Benekos, N. Nikolopoulos, S. Karellas, P. Grammelis, E. Kakaras Applied Energy, Volume 231, pp.380-398, 1 December 2018 doi.org/10.1016/j.apenergy.2018.09.043

[C13] Exergy analysis of a naturally ventilated Building Integrated Photovoltaic/Thermal (BIPV/T) system R. Agathokleous, S. Kalogirou, S. Karellas Renewable Energy, Vol. 128, Part B, pp. 541-552, December 2018 doi.org/10.1016/j.renene.2017.06.085

[C14] Equilibrium and kinetic aspects for catalytic methanation focusing on CO2 derived Substitute Natural Gas (SNG) E.-I. Koytsoumpa, S. Karellas Renewable and Sustainable Energy reviews, Vol. 94, pp. 536-550, October 2018 doi.org/10.1016/j.rser.2018.06.051

[C15] Preparation and investigation of distinct and shape stable paraffin/SiO2 composite PCM nanospheres G. Belessiotis, K. Papadokostaki, E. Favvas, E. Efthimiadou, S. Karellas Energy Conversion and Management, 168, pp. 382-394, 15 July 2018 doi.org/10.1016/j.energy.2018.02.044

[C16] 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, pp. 1-17, 30 June 2018 doi.org/10.1007/s12649-018-0388-5

[C17] Reversible Heat Pump–Organic Rankine Cycle Systems for the Storage of Renewable Electricity S. Staub, P. Bazan, K. Braimakis, D. Müller, C. Regensburger, D. Scharrer, B. Schmitt, D. Steger, R. German, S. Karellas, M. Pruckner, E. Schlücker, S. Will, J. Karl Energies Vol 11, Issue 6, Article number en11061352, June 2018 doi.org/10.3390/en11061352

[C18] The potential of WHR/batch and cullet preheating for energy efficiency in the EU ETS glass industry and the related energy incentives S. Karellas, S. Giannakopoulos, C.-S. Hatzilau, I. Dolianitis, G. Skarpetis, T. Zitounis Energy Efficiency, Vol. 11, Issue 5, pp. 1161-1175, June 2018 doi.org/10.1007/s12053-017-9587-3

[C19] Exergetic optimization of double stages Organic Rankine Cycle (ORC) K. Braimakis, S. Karellas Energy, 149, pp. 296-313, 15 April 2018 doi.org/10.1016/j.enconman.2018.04.059

[C20] Energetic optimization of regenerative Organic Rankine Cycle (ORC) configurations K. Braimakis, S. Karellas Energy Conversion and Management, Vol. 159, pp.353-370,1 March 2018 doi.org/10.1016/j.enconman.2017.12.093

[C21] Numerical analysis of a GPHE’s hydrodynamic and thermal charateristics, by applying an iterative procedure for the thermal boundary conditions S. Chapaloglou, A. Nikolopoulos, N. Nikolopoulos, S. Karellas, P. Vourliotis International Journal of Heat and Mass Transfer, 118, pp. 88-102, March 2018 doi.org/10.1016/j.ijheatmasstransfer.2017.10.106

[C22] Semi-empirical model of a multi-diaphragm pump in an Organic Rankine Cycle experimental unit F. D’Amico, P. Pallis, A.D. Leontaritis, S. Karellas, N.M. Kakalis, S. Rech, A. Lazzaretto Energy, 143, pp. 1056-1071, 15 January 2018 doi.org/10.1016/j.energy.2017.10.127

[C23] Comparative thermodynamic analysis of compressed air and liquid air energy storage systems P. Krawczyk, L. Szablowski, S. Karellas, E. Kakaras, K. Badyda Energy, 142, pp.46-54, 1 January 2018 dx.doi.org/10.1016/j.energy.2017.07.078

[C24] Thermal analysis of a Phase Change Material for a Solar Organic Rankine Cycle M. Iasiello, K. Braimakis, A. Andreozzi, S. Karellas Journal of Physics: Conference Series, Volume 923, Issue 1, 20 November 2017, Article number 012042 10.1088/1742-6596/923/1/012042

[C25] The Driving Factors of CO2 emissions from electricity generation in Greece: An Index Decomposition Analysis D. Diakoulaki, D. Giannakopoulos, S. Karellas International Journal of Global Warming, Vol. 13, Nos. 3/4, pp. 382-397, 2017

[C26] An environmental and economic evaluation of the lignite power generation system by using Life Cycle Analysis Principles D.-S. Kourkoumpas, G. Stamatiou, S. Karellas, P. Grammelis, E. Kakaras International Journal of Global Warming, Vol. 13, Nos. 3/4, pp. 296-329 2017

[C27] Energy and exergy analysis of adiabatic compressed air energy storage system L. Szablowski, P. Krawczyk, K. Badyda, S. Karellas, E. Kakaras, W. Bujalski Energy, 138, pp.12-18, November 2017. DOI: dx.doi.org/10.1016/j.energy.2017.07.055

[C28] Radial piston expander as a throttling valve in a heat pump: Focus on the 2-phase expansion G. Galoppi, R. Secchi, L. Ferrari, G. Ferrara, S. Karellas, D. Fiaschi International Journal of Refrigeration, 82, pp. 273-282, October 2017 DOI: dx.doi.org/10.1016/j.ijrefrig.2017.06.025

[C29] Experimental performance evaluation of a multi-diaphragm pump of a micro -ORC system G. Carraro, P. Pallis, A. Leontaritis, S. Karellas, P. Vourliotis, S. Rech, A. Lazzaretto Energy Procedia, 129, pp. 1018-1025, September 2017 DOI: 10.1016/j.egypro.2017.09.232

[C30] Experimental Investigation and CFD analysis of heat transfer in single phase subcooler of a small scale waste heat recovery ORC T. Roumpedakis, S. Chapaloglou, P. Pallis, A.-D. Leontaritis, S. Karellas, P. Vourliotis Energy Procedia, 129, pp. 487-494, September 2017 DOI: 10.1016/j.egypro.2017.09.166.

[C31] Adsorption of thiophene by activated carbon: A global sensitivity analysis P. Edinger, D. Grimekis, K. Panopoulos, S. Karellas, C. Ludwig Journal of Environmental Chemical Engineering, 5/4 pp. 4173-4184, August 2017 DOI: dx.doi.org/10.1016/j.jece.2017.07.041

[C32] Simulation of the reacting flow within a pilot scale calciner by means of a three phase TFM model M. Zeneli, A. Nikolopoulos, N. Nikolopoulos, P. Grammelis, S. Karellas, E. Kakaras Fuel Processing Technology, 162, pp. 105-125, July 2017. DOI: 10.1016/j.fuproc.2017.03.032

[C33] Integration of Organic Rankine Cycle with Lignite Flue Gas Pre-drying for Waste Heat and Water Recovery from Dryer Exhaust Gas: Thermodynamic and Economic Analysis X. Han, S. Karellas, M. Liu, K. Braimakis, W. Chen, J. Yan, E. Kakaras Energy Procedia, 105, pp. 1614-1621, May 2017. DOI: doi.org/10.1016/j.egypro.2017.03.518

[C34] Numerical investigation and comparison of coarse grain CFD – DEM and TFM in the case of a 1 MWth fluidized bed carbonator simulation A. Nikolopoulos, A. Stroh, M. Zeneli, F. Alobaid, N. Nikolopoulos, J. Ströhle, S. Karellas, B. Epple, P. Grammelis Chemical Engineering Science, 163 (2017), pp. 189-205, May 2017. DOI: 10.1016/j.ces.2017.01.052

[C35] Integrated thermoeconomic optimization of standard and regenerative ORC for different heat source types and capacities K. Braimakis, S. Karellas Energy, 121/15, pp. 570-598, February 2017. DOI: 10.1016/j.energy.2017.01.042

[C36] Technoeconomic Analysis and Comparison of a Solar-Based Biomass ORC-VCC System and a PV Heat Pump for Domestic Trigeneration K. Braimakis, A. Thimo, S. Karellas Journal of Energy Engineering, DOI: 10.1061/(ASCE)EY.1943-7897.0000397

[C37] Water extraction from high moisture lignite by means of efficient integration of waste heat and water recovery technologies with flue gas pre-drying system X. Han, J. Yan, S. Karellas, M., E. Kakaras, F. Xiao, Applied Thermal Engineering. 110, pp. 442-456, January 2017. DOI: dx.doi.org/10.1016/j.applthermaleng.2016.08.178

[C38] Energy recovery by means of a radial piston expander in a CO2 refrigeration system G. Ferrara, L. Ferrari, D. Fiaschi, G. Galoppi, S. Karellas, R. Secchi, D. Tempesti, International Journal of Refrigeration, 72 pp. 147-155, December 2016. DOI: dx.doi.org/doi: 10.1016/j.ijrefrig.2016.07.014

[C39] Exergy analysis of solar thermal collectors and processes S. Kalogirou, S. Karellas, K. Braimakis, C. Stanciu, V. Badescu, Progress in Energy and Combustion Science, 56, pp. 106-137, September 2016. DOI:10.1016/j.pecs.2016.05.002

[C40] Waste heat recovery at the glass industry with the intervention of batch and cullet preheating I. Dolianitis, D. Giannakopoulos, C.-S. Hatzilau, S. Karellas, E. Kakaras, E. Nikolova, G. Skarpetis, N. Christodoulou, N. Giannoulas, T. Zitounis Thermal Science, OnLine-First Issue 00, pp. 79-79, 2016 DOI: 10.2298/TSCI151127079D

[C41] Combustion and Emissions in an HSDI Engine Running on Diesel or Vegetable Oil Base Fuel with n-Butanol or Diethyl Ether As a Fuel Extender D. C. Rakopoulos, C. D. Rakopoulos, R. Papagiannakis, E. Giakoumis, S. Karellas, G. Kosmadakis Journal of Energy Engineering, DOI: 10.1061/(ASCE)EY.1943-7897.0000308

[C42] An investigation of the techno-economic parameters for the Power to Methanol concept D.-S. Kourkoumpas, E. Papadimou, K. Atsonios, S. Karellas, P. Grammelis and E. Kakaras, International Journal of Hydrogen Energy, 41/38, pp. 16674-16687, October 2016, dx.doi.org/10.1016/j.ijhydene.2016.07.100

[C43] Energy-exergy analysis and economic investigation of a cogeneration and trigeneration ORC-VCC hybrid system utilizing biomass fuel and solar power S. Karellas, K. Braimakis Energy Conversion and Management, 107, pp. 103–113, January 2016 Special Issue on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems ECOS-2014. dx.doi.org/10.1016/j.enconman.2015.06.080

[C44] Exergy analysis on solar thermal systems: A better understanding of their sustainability S. Kalogirou, S. Karellas, V. Badescu, K. Braimakis Renewable Energy, 85, pp. 1328–1333, January 2016 dx.doi.org/10.1016/j.renene.2015.05.037