Thesis supervisor: Béla Kovács
Location of studies (in Hungarian): Mathematics Institute Abbreviation of location of studies: MAT
Description of the research topic:
Over the past years, the energy optimization of existing residential buildings has been the main focus of the scientific community and specialist stakeholders. The effort was to minimize the specific annual energy consumptions in those. This action implies planning restrictions that do not comply with energy optimization; hence, it is sometimes more difficult to reduce the energy consumptions of existing buildings concerning the planning of buildings inspired by more modern principles. Moreover, energy consumption is not the only criterion characterizing this sector, and financial and/or environmental criteria should be taken into account. An energy upgrading should minimize the installation costs of improvement interventions, the costs concerning annual energy consumptions according to the primary sources exploited by the building (electric energy and natural gas), and the atmosphere's annual carbon dioxide emissions.
Spatial discretization of the heat conduction equation often yields huge and stiff systems of ordinary differential equations. Stiffness implies that conventional explicit methods are inappropriate because of unacceptably small timesteps. Thus they are rarely used in the industry. On the other hand, implicit methods require the solution of usually nonlinear algebraic equation systems at each time step. Moreover, it is hard to parallelize them.
The research aims to elaborate and optimize new numerical algorithms and methods to solve these systems. Computer codes will be written using these new methods, then the accuracy, stability, and robustness of the methods will be tested by comparison to at least one commercial software. The possibilities of the parallelization of the new methods will also be examined. When new methods' performance is found satisfactory, it will be applied to real life problems containing heat conduction in cooperation with the Department of Fluid and Heat Engineering. The main goal is to explore the optimal solutions adopted during retrofitting interventions according to the identified needs or the optimum balance. The criteria implemented in this study for the optimization are:
1) The minimization of the annual energy demand of the building
2) The minimization of the system installation and intervention costs
3) The minimization of the annual energy operating costs
4) The minimization of the amount of carbon dioxide emitted by the systems using nonrenewable energy resources.
The new methods will be tested in building energy, namely the investigation of the heat conduction in multilayer wall structures made of different materials. So-called thermal bridges form on the building's boundary structures, which have a major effect on the thermal performance, which means increased heat loss in the winter and heat gain in the summer. In the
wintertime, the inner surface temperature decreases, which increases the risk of condensation and mold growth. Some two- and three-dimensional heat transfer models have been developed in the literature to calculate heat conduction within thermal bridges. These models will be analyzed and compared with the results obtained by the new methods.
Research conditions:
The thermo-vision measuring tools needed to research the topic are available to validate the measurement results, and the ANSYS-FLUENT software system provides the background for further calculations.
Industry Background:
The research is basic but may have many industrial applications in the future, in all cases where heat transfer plays an important role (e.g., heating and cooling system).
References:
[1] K. Karabulut, E. Buyruk, A. Fertelli: Numerical investigation of the effect of insulation on heat transfer of thermal bridges with different types, Thermal Science 20(1), pp. 185- 195 (2016).
[2] E. Kovács, J. Majár: On some analogous transient phenomena, Miskolc, 2018, MultiScience - XXXII. microCAD International Multidisciplinary Scientific Conference.
[3] A. Gilicz: New stable method to solve heat conduction problems in extremely large systems, Design Of Machines And Structures 8: 2 pp. 30-38 (2018).
[4] V. Marincionia, N. Maya,, H. Altamirano-Medina: Parametric study on the impact of thermal bridges on the heat loss of internally insulated buildings, Energy Procedia 78, pp. 889-894 (2015).
[5] Salata, F., Ciancio, V., Dell'Olmo, J., Golasi, I., Palusci, O., and Coppi, M., 2020. Effects of local conditions on the multi-variable and multi-objective energy optimization of residential buildings using genetic algorithms. Applied Energy, 260, p.114289.
Number of students who can be accepted: 1
Deadline for application: 2022-05-31
2024. IV. 17. ODT ülés Az ODT következő ülésére 2024. június 14-én, pénteken 10.00 órakor kerül sor a Semmelweis Egyetem Szenátusi termében (Bp. Üllői út 26. I. emelet).
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