The effect of nanoparticles on the amount of solar heat energy stored in the phase-change material in a solar dryer

Bahari, Mehdi (2017) The effect of nanoparticles on the amount of solar heat energy stored in the phase-change material in a solar dryer. Masters thesis, university of Mohaghegh Ardabili.

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Text (بررسی تأثیر نانوذرات بر میزان ذخیره انرژی حرارتی خورشیدی در مواد تغییرفاز دهنده دریک خشک‌کن خورشیدی) Mehdi Bahari.pdf Download (729kB) | Preview

Abstract

Today, due to the disadvantages of using fossil fuels to dry food, Agricultural products and its contraceptive laws have been used in recent years Up to a percentage of the energy needed to dry food using solar energy. On the other hand, given that solar energy is not available at night and in cloudy days, the process of drying in solar dryers is largely dependent on the varying conditions of local weather, As a result, it is possible to use thermal storage systems and using appropriate heat storage materials, Avoids heat dissipation during the peak hours of the sun, and uses the maximum storage capacity for a long time after the sun's hours. One of the best ways to save energy resources is to use phase change materials. In this study, in order to store the maximum thermal energy from the heat collected by the solar collector during the day as well as to eliminate the fluctuations in the air temperature of the dryer compartment, The solar dryer was equipped with phase-change material (PCM). To increase the efficiency of phase-change materials, different types of nano-materials are added to them, Which has the effects of increasing the heat capacity, increasing the heat transfer coefficient and the thermal and chemical stability. In this study, alpha-alumina (AL2O3) nanoparticles with a purity of 99% and a size of 50 nm were dispersed into paraffin wax to synthesize aluminum oxide-paraffin nanocomposites. After the design, construction and optimization of the solar dryer, the machine was tested. The results showed that the amount of thermal energy absorbed in the AL2O3 paraffin nanocomposites was increased in comparison with pure paraffin. And the highest stored energy was stored in 1% by weight. And the results showed that the aluminum oxide nanoparticle improved the properties of paraffin wax. Also, to study the effect of thermal energy absorbed in different percentages, Givi fruit was used for drying. The final moisture content of the product was reduced by 69% to a final moisture content of 15% when used with 1.5% (paraffin + AL2O3).

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