Design, Fabrication and Performance Analysis of A Solar Water Heater
Abstract
This research is on solar water heater. An active solar heating system requires an external source of drive such as pump or electric motor. The main source of energy for this system is solar energy from the sun. It is cost free to heat the water and transfer heat to the fluid in the collector. The collector surface area is less than 1m2 and sourced locally. At moderate weather condition the collector temperature might be as high as 760C at ambient temperature of 250C. Improvement in thermal efficiency of the system based on the techniques to improve upon convective heat transfer. This is achieved by Insertion of twisted aluminum tapes and its geometry on the periphery of the fluid tube aided the effectiveness of heat transfer. The overall thermal efficiency of the system was 26.34%.
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Introduction
Heating of water represents a high percentage of energy consumption in homes and businesses. Solar energy has been able to supplement 30% of energy requirement for process water heating in our industries or domestic applications (Ertekin, 2006). To a large extent water heating using solar energy substantially displaced the use of convectional fossil fuels. This has been able to mitigate emission of green house gases and other pollutants; with the associated environmental issues.
A closed loop solar water heating system uses a heat transfer fluid to collect heat and a heat exchanger to transfer heat to domestic water supply. The set back of closed loop system is excessive heat loss during heat exchange process. Sitzmannx recommended the use of such system and provided basic information to manufacture and use closed loop system (Nahar, 2002).
A solar water heating system can be characterized as active or passive. An active system uses electric pump to circulate the fluid through the collector. A passive system moves the supply water or heat transfer fluid through the system without any pump but relies on thermo syphoning to circulate water. A solar flat plate collector of fixed orientation was fabricated and connected to the heat exchanger located inside the storage tank drum. The collector is a low temperature operating system at approximately 1000C.
Conclusion
In this research solar energy was used to heat water using the energy from the sun. The flat plate collector was fabricated in the Mechanical Engineering workshop of the University. The following parameters were measured : solar radiation, collector’s inlet and outlet temperatures, humidity of the environment and ambient temperature. Average maximum attainable temperature at the collector outlet point was 76.10C at ambient temperature of 250C.
Summarily passive solar heating should be suitable for the domestic sector and industrial establishments. It is also believed that solar water heaters as a source of renewable energy will have positive impact in reducing electrical energy consumption. It will also mitigate the generation of green house gases. It is established that this renewable energy source is abundantly available in Nigeria with estimated annual solar irradiation of 1900 to 2200kWh/m2 . Such high level of available solar energy could effectively be capitalized upon to generate electrical energy and energy for solar thermal applications in order to meet up with energy demand of Nigeria.