فهرست مطالب m. zabihi

In this study, aluminum/alumina composites with 1 and 3 vol% reinforcement particles were produced using powder metallurgy (PM); this was then followed by simple shear extrusion (SSE). Three SSE inserts with different distortion angles (α) were used in the SSE equipment. Three pressure values of 400, 600 and 800 MPa were selected for powder compression. Additionally, three different temperatures of 530, 550 and 570°C were chosen to evaluate the suitable sintering temperature and achieve the optimal SSE process. The effect of post-sintering annealing treatment on SSE feasibility was also investigated. In addition, porosity was measured by the Archimedes method and the microstructure of samples was evaluated using optical and scanning electron microscopy. Evaluation of the crystalline texture was examined by the X-ray method. It was found that the pressure of 800 MPa was the optimal value for the cold compression of powders and the temperature of 570℃ was the best sintering temperature. It was also observed that the temperatures 400℃ and 450℃ had no effect on increasing the number of SSE passes. Porosity of the Al-3 vol% alumina sample was changed from 5.75% to 5.02% after three SSE passes with α=10°. A preferred crystallographic texture was not seen due to the amount of effective strain and the presence of micro-pores, but a very low intensity cube texture {001} <100> was seen in some regions.

In the last century of Iranian architecture, the use of passive thermal comfort methods has been forgotten and replaced by active methods, in addition to environmental constraints and crises, this process have caused high costs and sometimes reduced access to electricity; As a result, it is essential to use elements and passive methods, especially in warm climates where more electricity is consumed. One of the most important elements of Iran's traditional architecture is wind tower which is still functional due to its simplicity of operation and use of wind energy. In recent years, the use of new building technologies, such as Phase Change Materials, has also led to the revival of passive methods and significant energy savings. Therefore, the present study has attempted to use this material in the wind tower to improve its performance in passive cooling.

This research was carried out in the form of modeling of airflow in the wind tower channel in Fluent Software and comparing the inlet and outlet temperature. In this regard, three models - fiberglass and two types of phase change with different melting constant temperatures as wall cover-were tested.

Testing of the models showed that the cover of the phase change material was much more effective than the fiberglass cover (at least between 4.5°C until 5.5°C) in reducing the outlet temperature of the wind tower.

This amount of cooling covers at least three months in warm season and some time of day in the warm and humid climate of Qeshm and will play a reliable role in reducing electricity consumption.