Journal of Sustainable Energy

4

Authors: LINGVAY I. , RADU E., UDREA O.

The widespread use of insulating oils (transformer oils) having mineral origin, because of their toxic organic substances and xenobiotic, poses a serious risk to the environment. Synthetic ester oils, although limited risk to the environment, its use is limited due to their relatively high price. This paper presents the preliminary results of the studies of the possible use of the natural ester oils of vegetable origin in the electrical equipment.

5

Authors: FIRINCĂ S.D., MIRCEA I., HIYASAT A., MIRCEA P.M

This paper simulates by using the Homer software, a distributed energy system with capacity below 1 MW. Among the renewable energy sources are used wind and solar energy. For photovoltaic panels, we are considering two situations: fixed panels, oriented at 45° and panels with tracking system with two axis. Simulation results contain information regarding operation hours of the system throughout the year, energy produced from the renewable energy sources, energy consumption for the load, and excess of electrical energy. The Homer software also allows an economic analysis of these systems.

6

Authors: RADU E., UDREA O., LINGVAY M., SZATMÁRI I., LINGVAY I.

Mineral insulating oils used in electrical equipment because of their toxic organic substances and xenobiotic, represents a major risk to the environment - to accidental spills pollute soil, groundwater and surface water. By microbiological tests were evaluated the biodegradability of some insulating oils used in electrical equipment. The assays were performed in comparison with edible sunflower oil and with a control sample (culture medium - without oil). The experimental results indicate that the mineral oils are more readily biodegradable than synthetic ester oil and vegetable oils. It was also found that oils with high sulfur content are more readily biodegradable.

7

Authors: BUZATU G.C., MIRCEA P.M., MIRCEA I., STAN IVAN F.E.

The energy performance of compressed air consumers aims to identify points in the process, on the basis of actual consumption of compressed air or electricity for its production, operation of the plant allows to obtain good results, as close to the nominal values for which it was designed. Establishing energy performance is achieved after performing (development) of real energy balance, based on measurements of specific energy consumption of energy facilities In this paper, the authors present the results of an energy analysis for an industrial transmission and distribution network of compressed air.

5

Authors: IONESCU G. C., BALOTA R.S., LOLEA M., BARLA E.

In this paper we will present the results of a simulation of an interior ventilation system which distributes fresh air in 2 office rooms. The aim is to study the distribution of the temperature inside the 2 rooms in the first seconds after the system starts. We analyzed the velocity and the temperature of the air in different scenarios. Also we are interested in finding the correct velocity which should be used by the system, in order not to determine a sudden temperature change in the room. The study is time dependent, and was simulated using Comsol 5.0 (demo version).

5

Authors: STAN IVAN F.E., MIRCEA I

The paper is structured in four parts. The first part presents the importance of thermal insulation for buildings energy economy and some insulation properties. In the second part of the paper it is described the reducing cost method to determine the energy savings. The third part of the paper includes an analysis and a comparison for an exterior wall provided with different thicknesses of insulation layer in order to determine the average savings cost. The last part presents conclusions and discussion.

6

Authors: RADULESCU V., DUMITRU S.

The paper is structured in seven parts, the last for few conclusions and finally some references. It is based on concrete measurements and observation during around 2 years. First is presented an introduction of the actual situation. In part two are mentioned the methods and hypotheses in evaluation of wind velocity distribution in boundary layers for atmospheric air, taking into account the roughness of ground surfaces. It is mentioned a concrete area, south part of Moldova. In third part is presented a solution for the geodetic model and finally are selected the altimetry solution. In chapter four is determined the influence of air density, temperature and pressure on wind turbine functioning. In the next chapters are presented the numerical model with special boundary conditions, taking into account different value of roughness and finally the obtained results. It is also estimated velocity variation during day-night. Finally is presented the vertical distribution of horizontal wind velocity for a wind farm, obviously important due the power of turbine (around 3 MW each one). Some conclusions and references are also mentioned.