Hybrid Renewable Energy Systems connected to the traditional power suppliers are an interesting technological solution in the field of energy engineering and the integration of renewable systems with other energy systems can significantly increase in energy reliability. In this paper, an analysis and optimization of the hybrid energy system, which uses photovoltaic modules and wind turbines components connected to the grid, is presented. The system components are optimized using two objectives criteria: economic and environmental. The optimization has been performed based on the experimental data acquired for the whole year. Results showed the optimal configuration for the hybrid system based on economical objective, that presents the best compromise between the number of components and total efficiency. This achieved the lowest cost of energy but with relatively high CO 2 emissions, while environmental objective results with lower CO 2 emissions and higher cost of energy and presents the best compromise between the number of components and system net present cost. It has been shown that a hybrid system can be optimized in such a way that CO 2 emission is maximally reduced and-separately-in terms of reducing the cost. However, the study shows that these two criteria cannot be optimized at the same time. Reducing the system cost increase CO 2 emission and enhancing ecological effect makes the system cost larger. However, depends on strategies, a balance between different optimization criteria can be found. Regardless of the strategy used economic criteria-which also indirect takes environmental aspects as a cost of penalties-should be considered as a major criterion of optimization while the other objectives including environmental objectives are less important.

No abstract

Ceiling diffusers are one of the most important elements of ventilation and air-conditioning installations. They have a significant impact on the speed and temperature distribution of air. The basic task of these devices is to provide the required air stream while maintaining its appropriate parameters in the occupied zone and low noise levels in the room. Square ceiling diffusers are designed for use in low- and medium-pressure ventilation systems. The diffusers allow obtaining 1, 2, 3 or 4-way air supply. Knowledge of the airflow formed by the diffuser is essential in order to ensure the comfort of people staying in a ventilated room. Designers of the diffusers nowadays mainly use advanced software and CFD (Computational Fluid Dynamics) modelling technique. CFD methods allow to quickly analyse the fluid flow. However, an very important problem is the consistency of the results obtained by numerical methods with the results obtained on an experimental way. The work presents a laboratory stand designed to test ceiling diffusers. In this research study the single square ceiling diffuser was experimentally and numerically analysed.

The increase in global energy consumption and the expected exhaustion of traditional energy sources, especially in the last century, led to an increased search for alternative sources of energy.The use of renewable energy sources has become extremely important to reduce dependence on fossil fuels. Due to the stochastic nature of the renewable energy sources such as the wind speed fluctuation and the intensity of solar radiation the stable operation of the systems base single renewable source can be problematic. But the using two or more of these sources results in higher stability than relying on a single source. For this reason, hybrid renewable energy systems have become an attractive solution in thefield of renewable energy. A hybrid energy system is a combination of two or more renewable energy sources that can enhance each another to increase the reliability of the supplied energy. The objective of this paper is investigation about the energy supplying improvement and the energy efficiency utilisation by hybridisation using two renewable energy resources: wind energy and solar energy with respect two different optimisation objectives: economical to reduce the net present cost and ecological to reduce CO2 emissions. Presented system has been implemented to supply a single household with an electric load.

In this work, we focus on utilization of hybrid renewable energy system for a residential load based in two different optimisation criteria. The presented system utilises photovoltaic modules wind turbines and batteries as energy storage. The analyses were carried out based on experimental measurements, for the electrical load, local solar radiation, wind speed and other environmental parameters. The optimisation process has been performed based on two aspects economic and ecological. The novelty of this work to find the relationship between two optimisation objectives.