A UNIMAID final year student , Muhammad jaafar from the department of physics has constructed a solar water heater, a water heater utilizing the sunlight to produce a hot water for domestic hot water demand. the solar water constructed from a locally available materials to minimize cost , made for simplicity of installation, reduce electricity bill and durability to meet domestic hot water demand.
a solar water heater exposed to sunlight
according to him , the solar water heater can heat water up to 70°C which sufficient for domestic water demand ; in his word “A solar water heating system for domestic use has been designed and constructed using locally available materials. Solar energy is received by a flat-plate collector consisting of a thin absorber plate, integrated with grids of fluid carrying tubes, and placed in an insulated casing with a transparent glass cover having a water tank integrated in the system. The radiation emitted by the absorber plate cannot escape through the glass, thus increasing its temperature. On the principle of thermosyphon, hot water is pushed through the collector and rises by natural convection to the water storage tank and cold water from the water tank simultaneously descends to the bottom header of the collector by gravity pull.
The water gets heated and flows into a storage tank through thermosyphon principle. The system was tested and Maximum fluid output temperature and the collector temperature, of 75°C and 70°C respectively, were obtained on a sunny day. This solar water heating system finds useful application and acts as a renewable energy resource in regions where there is abundant and consistent sunlight.”
He further explained the working principle of the solar water heater , in his words ” Principle of operation of a flat-plate solar water heater, The solar radiation passes through the glass in front of the absorber plate and strikes the flat black surface of the absorber plate where the solar energy is absorbed as heat (i.e. by increasing the internal energy).
This causes the flat-plate collector to become very hot, and so the water contained in the pipes bounded to the plate also absorb the heat by conduction. The water inside the tubes (risers/headers) expands and so becomes less dense than the cold water from the storage cylinder. On the principle of thermosyphon, hot water is pushed through the collector and rises by natural convection to the water storage tank and cold water from the water tank simultaneously descends to the bottom header of the collector by gravity pull.
|solar water heater showing the flat plate solar collector exposed to sunlight|
Therefore, there is circulation as a result of an increase in temperature and volume of the warmer water to the water storage tank. The circulation continues as hot water goes out, while cold water comes in.”
When asked what are advantages of this solar water heater , he said Solar water heaters based on thermosyphon principle have the following advantages: simplicity and low cost, requires no electrical supply, need no controller or pump, easy to install, can withstand mild sub-zero temperature, is reliable and long-lasting since there are no moving parts, scalable (several collectors can be connected in parallel to increase hot water supply), is easy to build and operate, no fuel cost, provides heated water of about 70 °C or within the range, and is portable.
They, however, have the following disadvantages: cannot withstand mains pressure, cannot give higher temperature water, are affected by weather conditions, very useful only during the dry season, and can be more practicable and useful in the sunny regions.”
when asked what is the significance of this project he said “ it designed to address challenges and threat pose by the use of fossil fuels ; such as the increase in oil demand accompanied with oil price rise, political crises in the world oil deports, depletion of oil reserve, reduced availability of fossil fuel, and other harmful effect attributed to the use of hydrocarbons such as, oil spillage, aquatic water pollution, agricultural soil degradation, ozone layer depletion, health hazards, and relatively tangible problems of aesthetics to problems of environmental conservation, greenhouse effect, and global climate change and other air pollution issues caused mainly by burning of these hydrocarbon as a source of heat energy .
The unavailability of electricity in most of our rural area, its high cost and inadequacy has led to the drive to use environmentally friendly, cheap and renewable alternative sources of heat energy to eliminate or minimize these negative effects. Presently, solar and other alternative energy resources are being harnessed for various applications such as power generation, air-conditioning, space heating, domestic hot water system, etc. “