There are number of problems associated with fossil fuels, most of which stem from the by-products created when they are burned to create energy. Chief among those by products are carbon dioxide and nitrous oxide, greenhouse gases that are major contributors to global warming. Renewable energies are far cleaner than fossil fuels. Many of the safety concerns surrounding fossil fuels, such as explosions on oil platforms and collapsing coal mines do not exist with renewable energies. Most renewable energies comes either directly or indirectly form the sun. sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for water heating, solar cooling and a variety of commercial and industrial uses. One way to produce electricity from the sun is by using the concentrating solar thermal systems. This is done by focusing the heat from the sun to produce steam. The solar industries, include parabolic linear concentrators, parabolic dishes, central receivers, Fresnel collectors, etc. Various restrictions such as high expenses, different linear expansion coefficient between glass and metal and the need for a complex sun tracker in parabolic collectors has resulted in developing of new solar technology systems. Fresnel collectors are one of these collectors which have dramatically reduced prices by replacing highly priced parabolic mirrors by flat mirrors. Though it is notable that efficiency of parabolic systems is slightly higher than Fresnel collectors. Fresnel collectors usually use a tube in order to receive concentrated sun radiation. In this project a new scheme has been designed to increase the efficiency of these collectors through an enhancement in exposed radiation flux. The use of a few absorbing tubes instead of one results in a noticeable growth of absorptive radiations which couldn’t be absorbed before and consequently the absorbed energy increases. In this project 7 groups of patterns were introduced to form the geometrical pattern of 5 absorptive tubes (in 99 conditions). Each of these patterns was simulated by MATLAB software and some parameters affecting their received flux such as distance from the mirror surface and the distance among absorber tubes were evaluated and the results were reported in the form of different priorities. Finally, The major parameters were evaluated by adding secondary reflectors which have flat and semicircular profile (these profiles are made of two or more angular parts). Conducted researches show that profiles with 2 horizontal receiver rows can absorb 95.5% of the received solar rays, using mirrors above the tubes. While, by using secondary semicircle and flat reflectors this number can be increased respectively to 96.8% and 97.3%. Keywords Solar energy, Fresnel collectors, absorptive tubes, secondary reflectors, ray tracking
