University of Twente Student Theses


Innovative sunlight driven thermal storage slurry for direct absorption solar collectors (DASC)

Chengappa, Rakshith Mukkatira (2019) Innovative sunlight driven thermal storage slurry for direct absorption solar collectors (DASC).

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Abstract:The solar energy is available freely in nature. Traditionally solar thermal receivers are used to utilize this carbon neutral energy. With recent advances in technology to improve the efficiency, and overcome the heating losses in the existing collectors, a new technology called Direct Absorption Solar Collector (DASC) is proposed. In this technology, the solar energy is directly absorbed and transferred by the working fluid. To overcome the time mismatch between availability and demand of solar irradiation, Phase Change Materials (PCMs) are added to the heat carrier. In this way, the latent heat can be exploited in combination with the sensible heat of the carrier itself. This innovative thermal storage slurry for DASC is in research phase but has numerous implications in building heating/cooling systems, thermal storage, and thermal regulating fabric. In this thesis, the objectives are 1- to design and install a laboratory scale stationary state DASC with simulated radiation source; 2-to examine the photo-thermal as well as thermal storage performance of the slurries; 3- to study the effect of different parameters like collector height, irradiation time on the collector efficiency when using PCM slurries. The PCM slurries used in this study contain different concentrations of palmitic acid/silicon-di-oxide and carbon black nanoparticles suspended in the pure water. The performance of the slurry in comparison to the pure water depends on the collector height and irradiation time. This study shows that for a receiver with the height of 13.5mm and radiation time of approximately one hour, the efficiency is 7.7% higher compared to that of water. In addition, for this slurry due to the introduction of latent heat thermal storage material along with carbon particles, there is an improvement of about 8.3% in the thermal storage density compared to water.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
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