HLINÍK, J. Optimalizace návrhu tepelného výměníku využívající materiál se změnou fáze pro akumulaci tepla [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2017.

Posudek vedoucího

Klimeš, Lubomír

The master thesis submitted by Juraj Hliník is concerned with the computer modelling and design optimization of the heat exchanger utilizing a phase change material for latent heat thermal energy storage. The student derived and implemented a computer model of the heat exchanger by means of the control volume method and the effective heat capacity method was employed for the latent heat modelling. The model was consequently used for design optimization of the exchanger which was carried out with the use of a genetic algorithm. The student decided to solve a challenging interdisciplinary problem which belongs to the area of mathematical programming, heat transfer with phase changes, and optimization. I appreciate that the student was able to apply and extend his knowledge in math, numerical methods, programming and he combined these skills with engineering heat transfer, thermal energy storage and design optimization. The student spent a lot of time with the implementation of the numerical model of the heat exchanger as the model was not working for a long time as it should work. The solution of issues related to the numerical model resulted in a lack of time for the solution of the part aimed at the design optimization which was assumed to be more comprehensive. Nevertheless, the student implemented a genetic algorithm coupled with his numerical model of the heat exchanger and two optimization cases for the charging period of the exchanger were investigated and optimized. I see the main outcomes of the thesis in (a) the implemented numerical-optimization codes for MATLAB and in (b) the improvement of student's skills in programming, heat transfer modelling, and optimization in MATLAB. I also appreciate that the thesis is written in English and that the student was able to go through books and scientific papers written in English. Juraj Hliník was working thoroughly and systematically, he often discussed the progress of the work with his supervisor. The language as well as the graphical level of the thesis is good, the thesis was typeset in LaTeX. The layout and the division into chapters and sections is also good, though re-ordering/modification of some parts would improve the legibility. The student proved the ability to independently solve an engineering problem, the aims were fulfilled, and the thesis contains all the mandatory parts. I therefore recommend the thesis for its defence with the grade good/C.

Posudek oponenta

Charvát, Pavel

The master’s thesis of Juraj Hliník deals with the optimization of the arrangement of Compact Storage Modules (CSMs) in a Latent Heat Thermal Energy Storage (LHTES) unit. The Compact Storage Modules considered in the thesis were flat aluminum containers (CSM panels) filled with a Phase Change Material (PCM). The goal of the optimization was to arrange an array of the CSM panels in a way to maximize the heat transfer rate between the passing air and the PCM. The array was limited to 100 CSM panels. The CSM panels were arranged in rows and layers. In the first part of his thesis the author introduces the theoretical bases of the conducted study. He starts with the basics of thermodynamics and continues with heat transfer, thermal energy storage, phase change modeling, numerical methods and mathematical optimization. This part of the thesis is unnecessarily long, constituting more than two-thirds of the thesis. Some theoretical bases need to be presented in the thesis but they should be closely integrated with the description of the conducted work. Some chapters read like a textbook and the direct links between the theoretical bases and the conducted work are often missing. The numerical model of the LHTES unit and the optimization of the arrangement of the CSM panels are described in the last two chapters (13 pages in total). The author adopted the energy balance method in combination with the effective capacity method for the numerical model of the LHTES unit. The genetic algorithm with the binary representation of the genes was used to optimize the array of the CSM panels. The feasible solutions were constrained by the minimal number of rows and layers of the CSM panels. The author obviously put a lot of work and effort into the development of the numerical model of the LHTES unit and to the optimization of its arrangement (both done in MATLAB). In order to be used in the optimization study the model of the LHTES unit had to allow calculations for different arrangements of the CSM panels. The creation of the numerical model and the optimization study clearly demonstrate the theoretical knowledge and the programming skills of Juraj Hliník. It is a pity that the model and the optimization study are not dealt with in more detail in the thesis.

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