دانلود رایگان مقاله فرنل خطی بازتابنده به عنوان سیستم خورشیدی برای گرم کردن آب

abstract

This work is concerned with assessing the thermal performances of a solar water heating system which is dependent on a linear Fresnel receiver (LFR) as a solar energy converter. The main objective of this paper is validation the experimental work carried out in the winter of 2015 on the concentrator in the climatic conditions of Algerian city “Blida” by a numerical simulation, where the tap water used as a heat carrier fluid. This simulation was used to solution of the energy balance equations of the absorber tubes and the water, where the solution is based on the finite difference method with an implicit scheme. After the solution of nonlinear equations, the program performed by using the MATLAB language gives the thermal efficiencies, the absorber temperatures, the water temperatures at the absorber tubes outlet, and thermal losses coefficients. The thermal efficiency of the reflector is exceeded 29%. The results obtained proved the existence of substantial convergence between the experimental and the numerical results, where in all cases the water temperature exceeded 347 K.

4. Conclusion

The linear Fresnel concentrator is a system that transforms solar energy into thermal energy. The primary aim of this paper was the validation of experimental results from a numerical simulation for the solar water heating system, where the linear Fresnel receiver as a device for thermal conversion. The performance of solar concentrator was evaluated in situ, where the tap water was used as a heat transfer fluid. The water is heated by the absorbed solar power that is transmitted by convection to the absorber tube.The study was started with thermal modeling of the absorber tubes which was built on a very precise mathematical model; the model is based on the energy balance between absorber tubes and transfer fluid. The implicit finite difference method was used to discretize the governing equations of the phenomenon. A computer program was developed to control performance of the concentrator. The program is written in the MATLAB language. The numerical results were compared with experimental results; it observed that the experimental and numerical results are convincing. The thermal efficiency of the concentrator exceeded 29%; the water temperature has reached up to 347 K, which the temperature range is low (at 60–80 °C). Results indicate that the performance of the solar reflector has a direct relationship with the direct solar radiation, the geometric and optical characteristics of a solar collector components and the climatic conditions of the site studied. The linear Fresnel reflector relies on solar energy, this latter can be used as solar water heating system; where the use of this device will solve many problems in many industrial of domestic areas.