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Heat transfer in solar energy equipment
Hylas, Martin ; Jegla, Zdeněk (referee) ; Babička Fialová, Dominika (advisor)
Photovoltaic panels are an efficient device for converting solar energy when exposed to high solar radiation intensity, which is, however, associated with a high ambient temperature. The high operating temperature of a photovoltaic panel has a negative effect on the efficiency and lifetime of the device. The first part of this thesis presents the current state of the art in the field of active and passive cooling methods for photovoltaic panels. The main metrics for evaluating the effectiveness of cooling systems are the cooling rate and the power gain of the photovoltaic module. The research shows that significant reduction of temperature effects can be achieved by support systems, but based on the experimental work to date there is no unified view on the applicability of the cooling devices in practice. Investment and operating costs are a significant barrier to the use of these systems by the general public. A possible solution to efficiently generate electricity and utilise otherwise wasted heat is to combine the functions of photovoltaic panels and solar thermal collectors into hybrid photovoltaic-thermal collectors. The tubular distribution system is an integral part of these installations. From a design point of view, these are simple systems, naturally subject to uneven distribution of the working medium, which results in a decrease in the efficiency of the entire device. In the second part of the thesis, the functionality of analytical models to predict the distribution of the working medium in a K-type distribution system is verified. The results of the comparison of predicted data with experimentally measured values show that the predictive ability of the analytical models is strongly dependent on the method of determining the value of hydraulic resistance (local losses).
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