Applied Mechanics and Materials Vol. 776

Abstract: As we secure sufficient space to distribute power generation equipment of solar energy, there will be no shaded area, but for the limited space, we can find temporaryshaded area surely for a few moments or a few hours .For the fixed type which are used to most roof solar power plant, side beam is projected for certain period of time before and after sunset, it would be affected to electric generation efficiency, so we researched to solve this phenomena using concave and convex mirror. For basic principle, when module is positioned at shaded area and time, it can deliver to be spread toward module to be accumulatedsunshine with concave mirror and reflected with convex mirror. For net energy which is obtained from sunlight, it produced 223W/day and it produced 207W/dayusing reflect mirror, we can get result which we can get similar amount of power energy only with reflect mirror.It shows that the production by direct light has increase of 8% more than production by reflected light.

Abstract: An alkaline fuel cell (AFC) is a device that converts the chemical energy of a fuel directly into electrical energy and heat. Efforts to improve the performance of the AFC is continuously conducted, and one of the work that has been investigated in this study was to examine the effect of the use of stainless steel as an electrode in the AFC. More specifically, this study focuses on to the influence of the thickness of the stainless steel plates used as an electrode. During the experiments, the design of the AFC with a particular dimension has been prepared with the flow of hydrogen enters at the anode and the flow of oxygen enters at the cathode at a certain pressure. Potassium hydroxide (KOH) is used as an electrolyte with a particular concentration dissolved in the water. The experiment results showed that the variation in the thickness of the stainless steel plates used as an electrode significantly affect the performance of the AFC. Similar results were also obtained for the effect of KOH concentration in the electrolyte also provide significant impact on the performance of the AFC, especially from the electrical voltage and current obtained during the experiment.

Abstract: In developing countries, the sun and biomass are very important as the alternative and renewable energy sources that is very necessary the effort for utilizing them maximally. This study has developed a natural hybrid dryer system utilizing the heat energy was generated from the biomass stove and the solar collector. This dryer system has been tested on the chimney height variation of exhaust moist air, namely: 2m, 4m, and 6m. For assessment of thermal efficiency, several variables of experimental data was collected consist of: several point of air flow temperatures, the ambient temperature, air flow velocities, mass of material which was dried, and solar radiation. Further, the efficiency of solar collector, the efficiency of biomass stove, the efficiency of drying chamber, and the total efficiency of system against the time as the purpose of this study. The result showed that with increased of chimney height of exhaust moist air caused the increase of air mass flow rate, and further caused the increase of heat transfer rate in the biomass stove and solar collector against the time. It caused the increased of transient thermal efficiency of biomass stove and solar collector against the time and it was influencing the increase of evaporation rate. Thus, the drying speed was increasing and with chimney height of 6m was the fastest with the drying time was 7 hours, while 7.5 hours and 8 hours were for height of 4m and 2m respectively. With increased of chimney height of exhaust moist air caused the efficiency of the drying chamber was decreasing and the total efficiency of system was increasing slightly, each was decreasing against the time due to decreasing of mass.