1. Coelho, L.; Koukou, M.K.; Konstantaras, J.; Vrachopoulos, M.G.; Rebola, A.; Benou, A.; Karytsas, C.; Tourou, P.; Sourkounis, C.; Gaich, H.; et al. Assessing the Effectiveness of an Innovative Thermal Energy Storage System Installed in a Building in a Moderate Continental Climatic Zone. Energies 2024, 17, 763. https://doi.org/10.3390/en17030763 
    
2. Dimitra I. Pomoni, Maria K. Koukou, Michail Gr. Vrachopoulos, Labros Vasiliadis, Circular economy: A multilevel approach for natural resources and wastes under an agri-food perspective, Water-Energy Nexus, 2024, https://doi.org/10.1016/j.wen.2023.12.003
    
3. N.T. Panagiotopoulos, A.G. Lekatou, K.A. Agrafioti, C.C. Prouskas, M.K. Koukou, J. Konstantaras, K. Lymperis, M.Gr. Vrachopoulos, G.A. Evangelakis, Anticorrosive AlN coatings for heat exchangers in thermal energy storage systems, Thermal Science and Engineering Progress, Volume 43, 2023, 102014, https://doi.org/10.1016/j.tsep.2023.102014
    
4. A. Kitsopoulou, E. Bellos, P. Lykas, M.Gr. Vrachopoulos, C. Tzivanidis, Multi-objective evaluation of different retrofitting scenarios for a typical Greek building, Sustainable Energy Technologies and Assessments 57, 2023, 103156 https://doi.org/10.1016/j.seta.2023.103156
    
5. Bellos, E.; Lykas, P.; Tsimpoukis, D.; Korres, D.N.; Kitsopoulou, A.; Vrachopoulos, M.G.; Tzivanidis, C. Multicriteria Analysis of a Solar-Assisted Space Heating Unit with a High-Temperature Heat Pump for the Greek Climate Conditions. Appl. Sci. 2023, 13, 4066. https://doi.org/10.3390/app13064066
    
6. Dimitrios Tsimpoukis, Evangelos Syngounas, Evangelos Bellos, Maria Koukou, Christos Tzivanidis, Stavros Anagnostatos, Michail Gr Vrachopoulos, Optimization analysis of Organic Rankine Cycle powered by waste heat of a supermarket transcritical CO2 multi-ejector refrigeration cycle, Journal of Cleaner Production, Volume 418, 2023, 138106, https://doi.org/10.1016/j.jclepro.2023.138106
    
7. Pomoni, Dimitra I., Maria K. Koukou, Michail Gr. Vrachopoulos, and Labros Vasiliadis. 2023. "A Review of Hydroponics and Conventional Agriculture Based on Energy and Water Consumption, Environmental Impact, and Land Use" Energies 16, no. 4: 1690. https://doi.org/10.3390/en16041690
    
8. Bellos, E.; Tsimpoukis, D.; Lykas, P.; Kitsopoulou, A.; Korres, D.N.; Vrachopoulos, M.G.; Tzivanidis, C. Investigation of a High-Temperature Heat Pump for Heating Purposes. Appl. Sci. 2023, 13, 2072. https://doi.org/10.3390/app13042072
    
9. Kitsopoulou, A.; Bellos, E.; Lykas, P.; Sammoutos, C.; Vrachopoulos, M.G.; Tzivanidis, C. A Systematic Analysis of Phase Change Material and Optically Advanced Roof Coatings Integration for Athenian Climatic Conditions. Energies 2023, 16, 7521. https://doi.org/10.3390/en16227521
    
10. Dimitrios Tsimpoukis, Evangelos Syngounas, Evangelos Bellos, Maria Koukou, Christos Tzivanidis, Stavros Anagnostatos, Michail Gr. Vrachopoulos, Thermodynamic and economic analysis of a supermarket transcritical CO2 refrigeration system coupled with solar-fed supercritical CO2 Brayton and organic Rankine cycles, Energy Conversion and Management: X, Volume 18, 2023, 100351, https://doi.org/10.1016/j.ecmx.2023.100351
     
11. Konstantaras J., Pagkalos C., Koukou M.K., Lymperis K., Caouris Y., Vrachopoulos M.G. Controller Evaluation for Solar-Latent Thermal Energy Applications. Journal of Energy and Power Technology 2022;4(2):18; DOI: 10.21926/jept.2202021
     
12. Maria K. Koukou, Christos Pagkalos, George Dogkas, Michail Gr. Vrachopoulos, Eleni Douvi, Yannis G. Caouris, Polykarpos Papadopoulos, Computational approach of charging and discharging phases in a novel compact solar collector with integrated thermal energy storage tank: study of different Phase Change Materials, Energies 2022, 15(3), 1113; DOI: https://doi.org/10.3390/en15031113
     
13. Evangelos Syngounas, Dimitrios Tsimpoukis, Maria K. Koukou, Michail Gr. Vrachopoulos, Energetic, exergetic and financial evaluation of a solar-powered absorption chiller integration into a CO2 commercial refrigeration system, Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy (2022), Volume 236, Issue 6. DOI: https://doi.org/10.1177/09576509221077540
     
14. Evangelos Syngounas, Dimitrios Tsimpoukis, Maria K. Koukou, Michail Gr. Vrachopoulos, Integration of a solar-powered absorption chiller for the performance enhancement of a supermarket CO2 refrigeration plant, Green Energy Sustain. 2(1):0003, (2022) DOI:  https://doi.org/10.47248/ges2202010003
     
15. Coelho, L.; Koukou, M.K.; Dogkas, G.; Konstantaras, J.; Vrachopoulos, M.G.; Rebola, A.; Benou, A.; Choropanitis, J.; Karytsas, C.; Sourkounis, C.; Chrysanthou, Z. Latent Thermal Energy Storage Application in a Residential Building at a Mediterranean Climate. Energies 2022, 15, 1008. DOI: https://doi.org/10.3390/en15031008
     
16. Dimitrios Tsimpoukis, Evangelos Syngounas, Evangelos Bellos, Maria Koukou, Christos Tzivanidis, Stavros Anagnostatos, Michail Gr. Vrachopoulos, Investigation of energy and financial performance of a novel CO2 supercritical solar-biomass trigeneration system for operation in the climate of Athens, Energy Conversion and Management, Vol. 245, 114583, (2021) DOI: https://doi.org/10.1016/j.enconman.2021.114583
     
17. Eleni Douvi, Christos Pagkalos, George Dogkas, Maria K. Koukou, Vassilis N. Stathopoulos, Υiannis Caouris, Michail Gr. Vrachopoulos, Phase Change Materials in Solar Domestic Hot Water Systems: A review, International Journal of Thermofluids, Vol. 10, 100075, (2021) DOI: https://doi.org/10.1016/j.ijft.2021.100075
     
18. G. Dogkas, J. Konstantaras, M.K. Koukou, M.Gr. Vrachopoulos, C. Pagkalos, V.N. Stathopoulos, P.K. Pandis, K. Lymperis, L. Coelho, A. Rebola, Development and experimental testing of a compact thermal energy storage tank using paraffin targeting domestic hot water production needs, Thermal Science and Engineering Progress, Vol. 19, 100573 (2020) DOI: https://doi.org/10.1016/j.tsep.2020.100573
     
19. G. Dogkas, M.K. Koukou J. Konstantaras, C. Pagkalos, K. Lymperis, V.N. Stathopoulos, L. Coelho, A. Rebola, M.Gr. Vrachopoulos, Investigating the performance of a thermal energy storage unit with paraffin as phase change material, targeting buildings’ cooling needs: an experimental approach, International Journal of Thermofluids, Vol 3-4, 100027 (2020) DOI: https://doi.org/10.1016/j.ijft.2020.100027
     
20. M.K. Koukou, G. Dogkas, M.Gr. Vrachopoulos, J. Konstantaras, C. Pagkalos, V.N. Stathopoulos, P.K. Pandis, K. Lymperis, L. Coelho, and A. Rebola, Experimental assessment of a full-scale prototype thermal energy storage tank using paraffin for space heating application, International Journal of Thermofluids, Vol 1-2, 100003 (2020) DOI: https://doi.org/10.1016/j.ijft.2019.100003
     
21. C. Pagkalos, G. Dogkas, M.K. Koukou, J. Konstantaras, K. Lymperis. M.Gr. Vrachopoulos, Evaluation of Water and Paraffin PCM as Storage Media for use in Thermal Energy Storage Applications: A Numerical Approach, International Journal of Thermofluids, Vol 1-2, 100006 (2020) DOI: https://doi.org/10.1016/j.ijft.2019.100006
     
22. Evangelos Bellos, Michalis Gr. Vrachopoulos, Christos Tzivanidis, Theoretical investigation of a novel hybrid refrigeration cycle based on the partial thermal isochoric compression, Thermal Science and Engineering Progress, Volume 11, June 2019, Pages 239-248. https://doi.org/10.1016/j.tsep.2019.04.003
     
23. M.K. Koukou; Dogkas, G.; Vrachopoulos, M.G.; Konstantaras, J.; Pagkalos, C.; Lymperis, K.; Stathopoulos, V.; Evangelakis, G.; Prouskas, C.; Coelho, L.; Rebola, A. Performance Evaluation of a Small-Scale Latent Heat Thermal Energy Storage Unit for Heating Applications Based on a Nanocomposite Organic PCM. ChemEngineering 3, 88, (2019). Available online at: https://doi.org/10.3390/chemengineering3040088
     
24. P.K. Pandis, S. Papaioannou, M.K. Koukou, M.Gr. Vrachopoulos, V.N. Stathopoulos, Differential scanning calorimetry-based evaluation of 3D printed PLA for phase change materials encapsulation or as container material of heat storage tanks, Energy Procedia, 161, 429-437, (2019). Available online at: https://www.sciencedirect.com/science/article/pii/S1876610219311683
     
25. Vasiliki Chalkia, Nikolaos Tachos, Pavlos K. Pandis, Aris Giannakas, Maria Koukou, Michalis Vrachopoulos, Luis Coelho, Athanasios Ladavos, Vassilis N. Stathopoulos, «Influence of organic phase change materials on the physical and mechanical properties of HDPE and PP polymers», RSC Adv., 8, 27438–27447 (2018). Available online at: https://pubs.rsc.org/en/content/articlepdf/2018/ra/c8ra03839b
     
26. M.K. Koukou, M.Gr. Vrachopoulos, N. S. Tachos, George Dogkas, Kostas Lymperis, and Vassilis Stathopoulos, "Experimental and computational investigation of a latent heat energy storage system with a staggered heat exchanger for various phase change materials", Thermal Science and Engineering Progress 7, 87–98, (2018) Open Access. Available online at: https://www.sciencedirect.com/science/article/pii/S2451904917303128
     
27. M.K. Koukou, M.Gr. Vrachopoulos, N. Tachos and N. Tsolakoglou, Design and development of a 10kWe ORC installation working with low temperature sources, 37 (9), 857-872 (2018). Available online at: https://www.tandfonline.com/doi/full/10.1080/14786451.2017.1383991
     
28. M.Gr. Vrachopoulos, N. Tachos, M.K. Koukou, G.K. Karanasiou, C. Karytsas, P. Tsekouras, and V. Drosou, Pre-assessment of a low-temperature geothermal and solar ORC system for power co-generation: the Effi low res approach, WSEAS TRANS ON ENVIRONMENT AND DEVELOPMENT, Vol. 11, 228-236, (2015). Available online at: http://www.wseas.org/multimedia/journals/environment/2015/a505815-093.pdf
     
29. M. Gr. Vrachopoulos, E. Kravvaritis, D. G. Stavlas, V. Stamatopoulos, A. Gonidis, and M. K. Koukou, Investigating the performance of a test phase change material chamber for passive solar applications: experimental and theoretical approach, International Journal of Sustainable Energy, Volume 34, 9, pp 614-627, (2015). Available on line at:https://www.tandfonline.com/doi/full/10.1080/14786451.2013.853065
     
30. M.Gr. Vrachopoulos, M.K. Koukou, N. Tachos, S. Kalognomos, A. Adamidis, F. Lavrenti, J. Pappas, P. Xygogianni, C.Karytsas, “Implementing the GEOPEAK Project in Greece towards the achievement of Europe 20-20-20targets:  Development and Evaluation of a Geothermal Heat Pump of High Efficiency”, Journal of Environmental Science, Vol. 3, pp 182-187 (2014). Available online at: http://environment.scientific-journal.com/toc/volume-3.html
     
31. M.Gr. Vrachopoulos, M.K. Koukou, G. Filos and C. Moraitis, Investigation of heat transfer in a triple-glazing type window at Greek climate conditions, Centr. Eur. J. Eng., 3(4) pp 750-763 (2013). https://doi.org/10.2478/s13531-013-0130-9 
32. Thanos G., Vrachopoulos M.Gr., Koukou M.K., Koulis A., Kakouris A.P., Thanos A.G., Residence site selection in urban and rural areas in Greece: A multiple-criteria decision analysis approach, Int. J. Applied Management Science, Vol. 4, n. 1, 36-51, (2012). https://doi.org/10.1504/IJAMS.2012.044870
     
33. Vrachopoulos, M.Gr. M.K. Koukou, D.G. Stavlas, V.N. Stamatopoulos, A.F. Gonidis, E.D. Kravvaritis, Testing reflective insulation for improvement of buildings energy efficiency, Central European Journal of Engineering, Vol. 2 n. 1, 83-90 (2012). https://doi.org/10.2478/s13531-011-0036-3
     
34. Vrachopoulos, M.Gr., M.K. Koukou, D.G. Stavlas, V.N. Stamatopoulos, A.F. Gonidis, E.D. Kravvaritis, Enhancement of Solar Thermal Energy Storage using Phase Change Materials: an Experimental Study at Greek Climate Conditions, International Review of Mechanical Engineering (IREME), Vol. 5 n. 2, pp. 279-284 (2011)
     
35. Stavrakakis, G.M., Koukou, M.K., Vrachopoulos, M.Gr., Markatos, N.C., Natural Cross-Ventilation in Buildings: Building-scale Experiments, Numerical Simulation and Thermal Comfort Evaluation, Energy & Buildings 40, 9, 1666-1681, (2008). https://doi.org/10.1016/j.enbuild.2008.02.022
     
36. Bacharoudis, E., Vrachopoulos, M.Gr., Koukou, M.K., Margaris, D., Filios, A.E., Mavrommatis, S.A., Study of the natural convection phenomena inside a wall solar chimney with one wall adiabatic and one wall under a heat flux approach, Applied Thermal Engineering, 27, 2266–2275, (2007). https://doi.org/10.1016/j.applthermaleng.2007.01.021
     
37. Papaefthimiou, V.D., Katsanos, C.O., Vrachopoulos, M.Gr., Filios, A.E., Koukou, M.K., Layrenti F.G., Experimental measurements and theoretical predictions of flow field and temperature distribution inside a wall solar chimney, Proc. IMechE Vol. 221 Part C: J. Mechanical Engineering Science, 33-41, (2007). https://doi.org/10.1243/0954406JMES308
     
38. Zervas, P., M.K. Koukou, N.C. Markatos, Predicting the effects of process parameters on the performance of phosphoric acid fuel cells using a 3-D numerical approach, Energy Conversion and Management, Vol. 47, no. 18-19, 2883-2899, (2006). https://doi.org/10.1016/j.enconman.2006.03.030
     
39. Zervas, P., M.K. Koukou, N.G. Orfanoudakis, N.C. Markatos, Evaluating low-temperature fuel cells performance for power generation: fluid dynamics study of PAFC systems at the cell level, Proc. IMechE Vol. 220 Part A: J. Power and Energy, 220 (6), pp. 525-533(9) (2006). https://doi.org/10.1243/09576509JPE229
     
40. Hatziapostolou, A., K. Krallis, N. G. Orfanoudakis, M. K. Koukou, D. Chatzifotis, G. Raptis, Numerical Prediction of the Flow Field produced by a Laboratory-Scale Combustor: a Preliminary Isothermal Investigation, WSEAS Transactions on Fluid Mechanics, Issue 3, Vol. 1, 230-236, (2006). http://wseas.us/e-library/conferences/2006evia/papers/516-370.pdf
     
41. Bacharoudis, E., Vrachopoulos, M.Gr., Koukou, M.K., Filios A.E., Numerical investigation of the buoyancy-induced flow field and heat transfer inside solar chimneys, WSEAS Transactions on Heat and Mass Transfer, Issue 2, Vol. 1, 193-198, (2006). http://www.wseas.us/e-library/conferences/2006evia/papers/516-367.pdf
     
42. Vrachopoulos, M.Gr., M.K. Koukou, G. Kotsiovelos, E. Kravvaritis, P. Ioannidou, Experimental evaluation of the performance of reflective insulation for improvement of indoor thermal environmental conditions, WSEAS Transactions on Environment and Development, Issue 3, Vol. 2, 173-178, (2006). http://www.wseas.us/e-library/conferences/2006evia/papers/516-366.pdf
     
43. Vrachopoulos, M.Gr., M.K. Koukou, N.W. Vlachakis, N.G. Orfanoudakis, G. Thanos, A.E. Filios, J. Kaldelis, ‘”Developing efficient tools to evaluate indoor environment issues: on-site measurements and numerical simulation of indoor air flow in a test room”, WSEAS Transactions on Environment and Development, Issue 2, Vol. 1, 288-293, (2005)