DESIGN OF HANDMADE SOLAR BOILER AND EFFECT OF THERMAL INSULATIONS IN HEAT CONSERVATION

Аннотация

This paper report the results of an experiment on a handmade solar boiler focusing on the effect of thermal insulations for better heat conservation and better efficiency of the device by using a concave downward dish covered by aluminum sheets, the dish used to reflect the solar radiation to the water tank. The boiler body is a box mad of polystyrene foam boards with length, width and height of 45cm, 43cm and 28.5cm respectively. The purpose of this research was to reach the 60⁰C water temperature, but handmade boiler reached a temperature about 10⁰c more than the target. Key words: solar boiler, thermal insulation, heat conservation. 1. Introduction The idea of using solar energy collectors to harness the sun’s power is recorded from the prehistoric times when at 212 BC the Greek scientist/physician Archimedes devised a method to burn the Roman fleet. Archimedes reputedly set the attacking Roman fleet afire by means of concave metallic mirror in the form of hundreds of polished shields; all reflecting on the same ship. The most widely-used solar thermal applications is the solar water heating (SWH) system [8]. In the nineteenth century, heating was a big problem. People generally used a cook stove for this purpose. They were using wood or heavy hods of coal lifted, then the fuel had to be kindled and the fire periodically stocked. In cities, the wealthier heated their water with gas manufactured from coal. To circumvent these problems, many handy farmers or prospectors or other outdoors men devised a much safer, easier, and cheaper way to heat water – placing into the sun a metal water tank painted black to absorb as much solar energy as possible. These were the first solar water heaters on record. The downside was that even on clear, hot days it usually took from morning to early afternoon for the water to get hot. And as soon as the sun went down, the tanks rapidly lost their heat because they had no protection from the low air temperature in the night. Nowadays many kinds of insulations are in researchers’ service to save the collected solar energy in a better manner. Thermal insulators have been used in heat storage systems to prevent temperature gradient thereby minimizing heat losses to the surroundings [4]. The thermal insulation is provided by embedding insulation materials at least on the roof areas and the vertical walls of the system [5]. New heat insulation material has been widely used in aerospace, energy, chemical and metallurgical industries, an important development trend is the research and development of composite function of heat insulation materials with low thermal conductivity [2]. In order to obtain the high strength and low thermal conductivity of composite insulation materials, The species and the composition of material need to change [3]. Because of the global concern about reducing carbon emissions, different policies could be applied to reduce carbon emissions, such as enhancing renewable energy deployment and encouraging technological innovations [6]. 658 ResearchBib IF - 11.01, ISSN: 3030-3753, Volume 2 Issue 11 According to the Renewable Energy Policy Network (2010), approximately 70 million houses use SWH systems worldwide [9]. Many countries started to use facilities which uses renewable energy, but this technology is young and novel in Afghanistan, that need research investigation. The solar energy has a very insignificant usage in heating water. The regional distribution of residential water heating fuel type in USA in as follows, 54% of the residential water heated by natural gas. 39% or the water heated by electricity, 6% of the demanded hot water heated by other sources of energy, but only 1% of the water heated by using the solar energy [1]. In America, with power accounting for 40% of CO2 emissions, the U.S. faces challenges in producing electricity cleanly [7]. The usage of renewable energy is felt to be increased, because the organic sources of energy will be finished and now it is the main cause of the air pollution. The appropriate design of SWH systems is important to assure good performance and maximize the economic benefits of these systems. These design methods can be broadly classified into two categories, namely, correlation-based methods and simulation-based methods [10]. 2. Methodology 2.1 Synopsis of boiler information Figures 1 (a) and 1(b) show the 3D views, and dimensions of the boiler, and figure 2 show the material used, wall section and detailed dimensions of walls and floor. To prevent the heat loss in three possible ways by radiation, convection, and conduction, we insulated the box as following techniques. The device is a box shaped boiler made of polystyrene foam boards of 3cm thickness, which polystyrene foam boards prevent the heat loss by conduction. Also the boiler walls and floor was insolated by aluminum foil to prevent heat loss by radiation, and to keep at minimum the heat loss by convection the box was air tighten as much as possibl