founded in 1954 and is now incorporated as a non-pro t educational and scienti c institution. With participation encompassing 100 countries, ISES® serves as a centre for information on research and development in solar energy utilisation. Through its publications and its sponsorship of technical conferences, the Society provides a world forum for the active consideration of solar energy.
A solar air heater (SAH) is a simple heater using solar radiation that is useful for drying or space heating. Unfortunately, heat transfer from the absorber plate to the air inside the solar air heater is low. Some researchers reported that obstacles are able to improve the heat transfer in a flat plate solar air collector and others found that a v-corrugated absorber plate gives better heat transfer than a flat plate. Yet, no work of combining these two findings is found.This paper describes the result of experimental study on a SAH with v-corrugated absorber plate and obstacles bent vertically started from 80oto 0owith interval 10oon its bottom plate. Experiments were conducted indoor at five different Reynolds numbers (1447 Re 7237) and three different radiation intensities (430, 573, and 716 W/m2).It is found that the obstacles improve SAH performance. Both the air temperature rise and efficiency increase with inserting obstacles bent at any angle vertically. Unfortunately, the air pressure drop is increasing, too. Obstacles bent vertically at smaller angle (means more straight) give higher air temperature rise and efficiency. However, the optimum angle is found 30o. The air temperature rise and efficiency will be 5.3% lower when the obstacles bent 30oinstead of 0o, but the pressure drop will be 17.2% lower.
A passive solar heater can be used to heat air in a room or water for some household needs. Passive solar heater can reduce the energy consumption by converting solar radiation energy to be thermal energy. Basically, a simple passive solar heater consists of absorber plate, thermal insulation, working fluid, cover, and structure to hold everything. This paper will discuss about the effect of Fresnel lens used as the cover and the air gap between cover and absorber plate on a passive solar water heater. The results of the experiment are that the commercial Fresnel lens could not gave the highest water temperature nor efficiency for passive solar water heater. The highest efficiency with glass cover and five-cm air gap was 22.8%. The smaller the air gap, the higher the water temperature in a passive solar water heater. The highest water temperature with glass cover and five-cm air gap was 63.8°C. The result of this experiment gives new challenge for the next research: we do the experiment in a solar water heater where water is circulated in a pipe and design until manufacture the new Fresnel lens.
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