DESIGN, SIMULATION, CONSTRUCTION AND PERFORMANCE EVALUATION OF A SOLAR OVEN
Abstract
A solar ovenis a device that converts solar energy into useful heat in a confined space (oven chamber) which can be utilised for cooking and baking purposes.The oven consists of plane reflectors to concentrate the solar radiation on the collector.The heat gain is maximum if the collector and reflectors are continuously adjusted such that the incidence angle of the reflected and direct radiations are minimised. In practise, it is always difficult to manually track the movement of the sun and the use of trackers can be very expensive. As such, an analytical model was developed to evaluate the optimum monthly collector and reflector tilts for maximum output hen employing the single axis tracking mode. The operation of the different components of the oven was modelled using TRNSYS, Microsoft Excel and EES programs alongside solar data for Zaria. Optimisation of the design was carried out based onweather conditions prevalent on the average day of the design month i.e. the month with the least solar radiation. The tilt angles of collector and reflectors required for the optimum collection of solar irradiation for each month were obtained from the simulation results of the oven model carried out for 12 months of the year. The optimum collector area and insulation thickness were also obtained through parametric studies by varying the aforementioned parameters until a stagnation temperature of 100ᵒC was obtained for the average day of the design month. The simulation results for the design with different collector areas and insulation thickness show that an area of 0.49m2 and thickness of 0.12m yields a stagnation temperature of 100ᵒC. However, the stagnation temperature achieved was insensitive to larger values of the design parameters.
CHAPTER ONE
INTRODUCTION
1.1 Background
Energy is the focal point of all human activities; it is the basis of industrial civilization. Without energy, modern life would cease to exist. In the past, the demand for energy sources was minimal because it was primarily used for cooking and local production. But as time went on, population increase and technological advancement led to more demand for energy. The major sources of energy are the conventional sources, which include: fossil fuels, and nuclear fuels. Fossil fuels, which include petroleum, coal, and natural gas, provide most of the energy need of modern industrial society. Other uses are found in the transportation, residential heating, and electric-power generation. Nuclear fuels are used to generate electricity, but it is utilised mainly in the developed countries due to high level of supervision and maintenance required. The non-conventional (renewable) sources of energy include: hydroelectric power, solar energy, wind energy, biomass, ocean thermal energy, tidal energy, and geothermal energy, but the potential of these sources is still underutilised because they are much more expensive to harness than energy derived from fossil fuels. Hydroelectric power requires a large capital investment, so it is often uneconomical for a region where coal or oil is cheap. As such, they contribute a little percentage to the massive energy requirement of the world population. However, the fear of depletion of fossil fuels due to the fast rate of consumption has provoked further development of these alternative energy sources, such as solar energy.
