doc. Ing. Lubomír Klimeš, Ph.D.
E-mail:   klimes@fme.vutbr.cz  WWW:   http://sites.google.com/a/vutbr.cz/klimes Dept.:   Energy Institute Dept. of Thermodynamics and Environmental Engineering Position:   Associate Professor Room:   A2/406

Supervised courses:

• Applied Thermomechanics (9ATH)
• Bachelor Seminar (6A-A)
• Bachelor Seminar (6A)

Publications:

• ŠTĚTINA, J.; MAUDER, T.; KLIMEŠ, L.; CHARVÁT, P.:
  Melting front propagation in a paraffin-based phase change material-lab-scale experiment and simulations
  journal article in Web of Science
• KLIMEŠ, L.; CHARVÁT, P.; HEJČÍK, J.:
  Comparison of the energy conversion efficiency of a solar chimney and a solar PV-powered fan for ventilation applications, MDPI
  journal article in Web of Science
• STRITIH, U.; CHARVÁT, P.; KOŽELJ, R.; KLIMEŠ, L.; OSTERMAN, E.; OSTRÝ, M.; BUTALA, V.:
  PCM thermal energy storage in solar heating of ventilation air - Experimental and numerical investigations, Elsevier
  journal article in Web of Science
• KLIMEŠ, L.; POPELA, P.; MAUDER, T.; ŠTĚTINA, J.; CHARVÁT, P.:
  Two-stage stochastic programming approach to a PDE-constrained steel production problem with the moving interface, Institute of Information Theory and Automation of The Czech Academy of Sciences
  journal article in Web of Science
• PÍŠTĚK, V.; KLIMEŠ, L.; MAUDER, T.; KUČERA, P.:
  Optimal design of structure in rheological models: an automotive application to dampers with high viscosity silicone fluids, JVE International
  journal article in Web of Science
• KLIMEŠ, L.; MAUDER, T.; CHARVÁT, P.; ŠTĚTINA, J.:
  A Front Tracking Method Accelerated by Graphics Processing Units for Phase Change Modelling in Latent Heat Thermal Energy Storage: A Comparison with Interface Capturing Methods ,
  CHEMICAL ENGINEERING TRANSACTIONS , pp.1-6, ISBN 978-88-95608-51-8, (2017), Aidic Servizi Srl
  conference paper
  akce: 20th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (PRES17), Tianjin, 21.08.2017-24.08.2017
• MAUDER, T.; CHARVÁT, P.; ŠTĚTINA, J.; KLIMEŠ, L.:
  Assessment of Basic Approaches to Numerical Modeling of Phase Change Problems—Accuracy, Efficiency, and Parallel Decomposition, The Americal Society of Mechanical Engineers ASME
  journal article in Web of Science
• HEJČÍK, J.; CHARVÁT, P.; KLIMEŠ, L.; ASTROUSKI, I.:
  A PCM-water heat exchanger with polymeric hollow fibres for latent heat thermal energy storage: A parametric study of discharging stage
  journal article in Web of Science
• KLIMEŠ, L.; MAUDER, T.; CHARVÁT, P.; ŠTĚTINA, J.:
  An accuracy analysis of the front tracking method and interface capturing methods for the solution of heat transfer problems with phase changes,
  Journal of Physics: Conference Series, pp.1-8, (2016), IOP Publishing
  conference paper
  akce: 7th European Thermal-Sciences Conference EUROTHERM 2016, Krakov, 19.06.2016-23.06.2016
• KLIMEŠ, L.; ŠTĚTINA, J.:
  A rapid GPU-based heat transfer and solidification model for dynamic computer simulations of continuous steel casting, Elsevier
  journal article in Web of Science
• KLIMEŠ, L.; ŠTĚTINA, J.:
  Unsteady model-based predictive control of continuous steel casting by means of very fast dynamic solidification model on GPU, Insitute of Metals and Technology
  journal article in Web of Science
• CHARVÁT, P.; KLIMEŠ, L.; ŠTĚTINA, J.; OSTRÝ, M.:
  Thermal storage as a way to attenuate fluid temperature fluctuations - sensible vs. latent heat storage materials, Insitute of Metals and Technology
  journal article in Web of Science
• CHARVÁT, P.; KLIMEŠ, L.; OSTRÝ, M.:
  Numerical and experimental investigation of a PCM-based thermal storage unit for solar air systems, Elsevier
  journal article in Web of Science
• KLIMEŠ, L.; ŠTĚTINA, J.; BUČEK, P.:
  Impact of casting speed on the temperature field of continuously cast steel billets,
  Materiali in tehnologije, Vol.47, (2013), No.4, pp.507-513, ISSN 1580-2949, Insitute of Metals and Technology
  journal article - other
• ŠTĚTINA, J.; MAUDER, T.; KLIMEŠ, L.; KAVIČKA, F.:
  MINIMIZATION OF SURFACE DEFECTS BY INCREASING THE SURFACE TEMPERATURE DURING THE STRAIGHTENING OF A CONTINUOUSLY CAST SLAB,
  Materiali in tehnologije, Vol.47, (2013), No.3, pp.311-316, ISSN 1580-2949, IMT Ljubljana
  journal article - other
• KLIMEŠ, L.; CHARVÁT, P.; ŠTĚTINA, J.:
  Mathematical Model of Multi-Layer Wall with Phase Change Material and its Use in Optimal Design,
  Advanced Materials Research, Vol.649, (2013), No.1, pp.295-298, ISSN 1022-6680, Trans Tech Publications
  journal article - other
• KLIMEŠ, L.; CHARVÁT, P.; OSTRÝ, M.:
  Challenges in Computer Modeling of Phase Change Materials, Inštitut za kovinske materiale in tehnologije Lubljana
  journal article in Web of Science
• ŠTĚTINA, J.; KLIMEŠ, L.; MAUDER, T.; KAVIČKA, F.:
  FINAL-STRUCTURE PREDICTION OF CONTINUOUSLY CAST BILLETS, IMT Ljubljana
  journal article in Web of Science

List of publications at Portal BUT

Abstracts of most important papers:

• KLIMEŠ, L.; CHARVÁT, P.; HEJČÍK, J.:
  Comparison of the energy conversion efficiency of a solar chimney and a solar PV-powered fan for ventilation applications, MDPI
  journal article in Web of Science
  A study into the performance of a solar chimney and a solar photovoltaic (PV)-powered fan for ventilation applications was carried out using numerical simulations. The performance of the solar chimney was compared with that of a direct current (DC) fan powered by a solar PV panel. The comparison was carried out using the same area of the irradiated surface—the area of the solar absorber plate in the case of the solar chimney and the area of the solar panel in the case of the photovoltaic-powered fan. The two studied cases were compared under various solar radiation intensities of incident solar radiation. The results indicate that the PV-powered fans significantly outperform solar chimneys in terms of converting solar energy into the kinetic energy of air motion. Moreover, ventilation with PV-powered fans offers more flexibility in the arrangement of the ventilation system and also better control of the air flow rates in the case of battery storage
• STRITIH, U.; CHARVÁT, P.; KOŽELJ, R.; KLIMEŠ, L.; OSTERMAN, E.; OSTRÝ, M.; BUTALA, V.:
  PCM thermal energy storage in solar heating of ventilation air - Experimental and numerical investigations, Elsevier
  journal article in Web of Science
  Heating of ventilation air accounts for a significant part of energy consumption in buildings. The paper presents the use of latent heat thermal energy storage (LHTES) heated with a hot air solar energy collector mounted on the facade of the office building at the Faculty of Mechanical Engineering in Ljubljana where experiments have been carried out. The numerical model of the LHTES unit was developed at the Brno University of Technology, implemented as a type in the TRNSYS simulation tool and validated with experimental results. With the use of the developed model the annual savings of the unit were calculated.
• HEJČÍK, J.; CHARVÁT, P.; KLIMEŠ, L.; ASTROUSKI, I.:
  A PCM-water heat exchanger with polymeric hollow fibres for latent heat thermal energy storage: A parametric study of discharging stage
  journal article in Web of Science
  The paper presents a theoretical parametric study into latent heat thermal energy storage (LHTES) employing polymeric hollow fibres embedded in a phase change material (PCM). The polymeric hollow fibres of five inner diameters between 0.5 mm and 1.5 mm are considered in the study. The effectiveness-NTU method is employed to calculate the thermal performance of a theoretical LHTES unit of the shell-and-tube design. The results indicate that the hollow fibres embedded in a PCM can mitigate the drawback of low thermal conductivity of phase change materials. For the same packing fraction, the total heat transfer rates between the heat transfer fluid and the PCM increase with the decreasing diameter of the hollow fibres. This increase in the heat transfer rate and thus the efficiency of the heat exchange to some extent compensate for the energy consumption of the pump that also increases with the decreasing fibre diameter.
• KLIMEŠ, L.; ŠTĚTINA, J.:
  A rapid GPU-based heat transfer and solidification model for dynamic computer simulations of continuous steel casting, Elsevier
  journal article in Web of Science
  The paper presents a GPU-based model for continuous casting of steel. The model provides rapid computation capabilities required for real-time use in the casting control and optimization. The fully three-dimensional formulation of the heat transfer and solidification model is based on the control volume method and it allows for very fast transient simulations of the thermal behaviour of cast strands. The developed model has been verified on Stefan problem and validated with industry measurements. Heat transfer conditions in the mould and secondary cooling were determined experimentally in lab-scale experiments. The computational model is implemented as highly-parallel with the use of the NVIDIA CUDA architecture, which enables to launch the model on graphics processing units (GPUs) allowing for its great acceleration. The acceleration can be evaluated with the use of the relative computational time, which is the dimensionless ratio between the computational time that the model needs to compute the simulation and the wall-clock time of the real casting process being simulated. The relative computational time of the presented GPU-based computational model is between 0.0016 for a coarse mesh and 0.27 for a very fine mesh. The corresponding multiple of the GPU-acceleration, which is the ratio between the computational time of the GPU-based model and of the CPU-based model for the identical simulation, is between 33 and 68.
• CHARVÁT, P.; KLIMEŠ, L.; OSTRÝ, M.:
  Numerical and experimental investigation of a PCM-based thermal storage unit for solar air systems, Elsevier
  journal article in Web of Science
  A general problem of most solar thermal systems is the need for thermal storage in order to balance supply and demand of heat over a certain period of time. A possibility to employ latent heat of fusion in phase change materials (PCMs) for thermal energy storage in air-based solar thermal systems was investigated using laboratory experiments and numerical simulations. A heat storage unit containing 100 aluminium panels filled with a paraffin-based PCM was used in the investigations. The experiments were carried out in a lab environment with an electric air heater as a heat source. A numerical model of the unit was developed and implemented as a type in the TRNSYS 17 simulation tool. The results of the simulations with the developed model show a good agreement with experimental results. Subsequently, the model was used for a parametric study analysing the influence of certain parameters. The performed investigations showed a potential of the use of latent heat thermal storage in air-based thermal systems with a narrow temperature operation range.