DESIGN, CONSTRUCTION AND PERFORMANCE EVALUATION OF A PASSIVE SOLAR WATER HEATER

ABSTRACT
Solar energy being transmitted from the sun through space to earth by electromagnetic radiation must be converted to heat before it can be used in a practical heating or cooling system. Solar energy collectors, the devices used to convert the suns radiation to heat, usually consist of a surface that efficiently absorbs radiation and converts this incident flux to heat which raises the temperature of the absorbing material.There is the need for adequate research to be carried out on the solar heating system so as to make recommendations on the right design to improve it performance and save energy costs. The objective of this work is to provide energy for heating water for domestic and industrial use, to publicize the knowledge to potential users and for commercial purposes, to make relevant recommendations based on the outcome of the research so as to improve the efficiency of the solar water heating system. In this research work, solar water heating system has been designed and constructed using locally available materials. Solar energy is received by a flate plate collector consisting of an absorber plate made up of galvanized sheet with a length of 110 cm, a width of 80 cm and a thickness of 0.7 mm. The zigzag-pipe is fixed to the sheet and then painted dull-black., integrated with fluid carrying tubes, and place in an insulated casing with a trasparent glass cover having a storage tank integrated in the system. The radiation emmited by the absorber plate cannot escape through the glass, thus increasing it temperature. The water gets heated and flows into the storage tank through the thermosyphon principle.The system was tested in the month of August 2017. The maximum temperature of the heated water and collector surface temperature of 85 0C and 75 0C respectively, were recorded between the hours of 1:00 pm and 2:00 pm on a sunny day. This solar water heating system finds useful application in homes and industries. The solar water heater can be used in regions where there is abundant and consistent sunlight. Based on this research work, it is recommended that the insulation layer should be made up of styro-foam because it has greater ability to prevent heat loss and a separate tank be provided for the heated water.
CHAPTER ONE
INTRODUCTION
1.1         Background of the Study
Renewable energy resources of which the sun is a good example, are those resources which undergo a faster replenishment rate within a relatively short time than the rate at which they are utilized or depleted. The energy of the sun is generated from the nuclear fusion of its hydrogen into helium, with a resulting mass depletion rate of approximately 4.7 × 106 tons per second. The earth’s population currently needs 15 TW of power in total, but the solar radiation that reaches the earth on a continuous basis amounts to 120,000 TW; hence, just a fraction of the suns energy reaching the earth will cover the bulk of energy requirements (Bradke et al., 2011).
Solar energy being transmitted from the sun through space to earth by electromagnetic radiation must be converted to heat before it can be used in a practical heating or cooling system. Since solar energy is relatively dilute when it reaches the earth, the size of a system used to convert it to heat must be relatively large. Solar energy collectors, the devices used to convert the suns radiation to heat, usually consist of a surface that efficiently absorbs radiation and converts this incident flux to heat which raises the temperature of the absorbing material. A part of this energy is then removed from the absorbing surface by means of heat transfer fluid that may either be liquid or gaseous. One of the simple forms of solar energy collectors built is the flat-plate collector (Nosa et al., 2013).
Solar water heaters can operate in any climate. Performance varies depending on how much solar energy is available at the site, but also on how cold the water coming into the system is. The colder the water, the more efficiently the system operates. In almost all climates, you will need a conventional backup system. In fact, many building codes are required to have a conventional water heater as the backup.
Even in our country Nigeria, people from several areas often put water outside, so that after getting warm, it could be used for things like bathing, drinking and other thermal comforts. Seeing the solar energy or solar water heater in particular today, it is clear that solar water heater have undergone several modifications for more efficiency.

1.2         Statement of Problem
Since the 1970’s, residential solar technology has emerged as a result of the increasing cost of energy consumption, which in most cases is used for heating and cooling, is typically the most significant operational cost in residential buildings. Many attempts have been made thereafter to save cost on heating and cooling energy. Although the features of each specific solar heating system vary, the basic components of a solar heating system are the same. It should at least include: a collector, where heat is collected from the solar energy; heat storage and a heat circulation system (Shurcliff, 1979).
Thus, there is the need for adequate research to be carried out on the solar heating system so as to make recommendations on the right design to improve it performance and save energy costs.

1.3         Aim and Objectives
The main aim of this work is the development of a low cost solar water heater, constructed using a high percentage of locally available materials. The objectives of this work are:
(i)                 To provide energy for heating water for domestic and industrial use.
(ii)               To publicize the knowledge to potential users and for commercial purposes.
(iii)             To make relevant recommendations based on the outcome of the research so as to improve the efficiency of the solar water heating system.