Journal of Sustainable Energy

6

Authors: M. ZHENG, L. ZHANG.

In the present paper, the effect of wind speed on the critical width of simulation region for the 5- blade drag typed VAWT is studied, which is based on simulation of CFD with FLUENT soft. Sliding grid and PISO algorithm are employed in the simulation. Varying inlet wind speeds from 6.0m/s to 9.0m/s, are employed to perform the effect of wind speed study. It indicated that the critical width of the simulated region increases with the inlet wind speed linearly.

9

Authors: GHEORGHE C.

Based on an extensive bibliographic synthesis, the present paper presents the state of the art and the characterisitics of the an electric power system onboard shipping vessels and their structure, the criteria to be taken into account during the design phase for the selection of voltage, current and frequency in the bars of the main distribution panel, for the purpose of supplying consumers on-board, and the calculation methods for power requirement analysis to choose the number of on-board synchronous generators and their power. The paper concludes with a case study, which analyzes the functional construction of an electric power system on board an oil tanker, with the presentation of the management system for the synchronous generators and consumers onboard the ship.

16

Authors: VASIU I.

The energy evolution of Oradea and Zalau cities after 1918 took place in the difficult circumstances of Romania affected by two world wars and by a financial crisis in 1929-1933 interwar period. Thus, in the years following 1918, economic development of Romania was slow, with a peak in 1938. Low-power energy installations, generally smaller than 1 MWe, have supplied electricity to the towns and local industry. After 1950, a large number of hydro and thermal power plants were built in Romania, which have been interconnected in the National Energy System, providing electricity and heat to the industrial and dweling expansion. The paper presents some aspects of the energy field achievements in Oradea and Zalau, registered after 1918 until 1945, especially with regard to the cogeneration thermal power plants built in these cities in the 1960s – 1980s. Cogeneration thermal plants achieved in Oradea and Zalau have had an installed power capacities of 355 MWe and 24 MWe respectively, which have contributed to the economic and social development of these cities, but as we saw, the return to democracy in Romania after 1990 meant stopping and dismantling a great part of the industrial units, these thermal plants needed to be closed, as a result of the heat consumption base sharp decreasing, mainly after 2005-2010. In Oradea, an up to date 47 MWe and 51 MWt gas turbine cogeneration plant was established from non-reimbursable European funds, which supplied the city with thermal energy from winter 2016/2017, but in Zalau the municipality has given up at the district heating system in the favor of the low capacities thermal installations, working on natural gas, placed at the consumers.

4

Authors: KARMOUCH R., EL HOR H.

The accumulation of dust on the solar cells panels worsens the situation and lowers the efficiency of the solar cells day by day especially in the regions known by their high rate of dust, low frequency and intensity of rain. The accumulated dust on the solar cells panel blocks the cells from the sun’s rays and act as a screening effect as shown by the calculated spectral transmittance of dust which decreases the performance of the solar cells over time until the cell panels are cleaned manually or by rain. The tilt angle of the solar cell panels affects considerably the amount of accumulated dust on the surface of the panels. The study focuses on the effects of dust accumulation on photovoltaic solar panels in Jazan region. The effect is tested in outdoor measurements and it was found that regular dust accumulation reduces the solar cells efficiency by about 10% for an exposure time of 16 weeks. Moreover the tilted panel with an angle of 30o receives more dust than the panel tilted by 50o which means higher efficiency loss for the lower tilted panel. The efficiency loss is significant of large of annual monetary losses. This study can be considered as a reference to predict the level of degradation of any photovoltaic system that might be installed in the Jazan region and also to estimate the real cost include the cost of the solar panel cleaning.

5

Authors: FELEA. I., KUBOLA T., MIHUTA S.

Energy efficiency improvement program for an organization that consumes a significant amount of energy is an important document, both through fulfillment of obligations and especially through utility of identified measures on improving EnEF. and economic. After evoking the regulatory framework and the usefulness of this concerns, the paper presents the working methodology in making identifications MIEnEF for a TC and the results for Turism Felix.

7

Authors: ALBUT-DANA D., RANCOV N., FELEA A.I., CHIREA V., VESE C.

In the paper is presented anelectrical behavioranalysis of an industrial consumer. The analysis has the purpose to identify the solutions to increase of energy efficiency, also pointing out the extend of the recommendations that has been applied in this regard, in the elaborated electricity audits. In the first part of the paper is made a justification of preoccupation and is presented the objective of analysis. The second part has the working methodology. Then follows the results obtained and on the last part the conclusions of analysis is given.

5

Authors: FETEA M., MARE R.

The paper is structured in five parts. In the first part is evoked the importance and presented some aspects from stability theory. In the second part are presented the general model designed by the author with the principal loads. In part three are presented the model for evaluation taking into account the forces given by the wind loads. In part four are given the results obtained using an analytical method neglecting the forces given by the wind loads. Are calculated the dimensions of the diameter and also is verified the section. In part number five the authors presents the conclusions.

7

Authors: RADULESCU V.

The present paper is structured in six parts. In the first part are mentioned the topic importance and the new problems appeared into last decades, related to the environmental problems in natural or hydropower lakes. This new solution using renewable resources based on PV-photovoltaic panels intends to resolve these aspects. As area for testing were selected two natural reservations lakes. Based on some experimental measurements made during three months in 2015, was determined the quality of water, main parameters, presented in part two. In the third part are briefly presented the actual environmental conditions and in part four the effects on the active sludge deposits appeared due excess developed vegetation. In part five is presented the prototype model used to solve the local problem, to collect, compact and partially dry the active sludge. The extracted sludge can be in short time integrally consumed for agricultural purpose, as ecologic and nutritive fertiliser as to restore the agriculture lands. The sludge, knew in the past for its therapeutic utilisation, more then one hundred ago, nowadays due ecological and biological changes lost his efficiency. The reconstruction of the local ecologic balance and for the sludge to recover its therapeutic properties using renewable resources without disturb the environment are the main objectives of this research. Finally some conclusions and references are presented.

7

Authors: POP O., BARBULESCU C., KILYENI ST., VERNICA A.

The interconnected capacity and transmission cost allocation is tackled in this paper. Two methods are involved: distribution factors and equivalent bilateral methods. For the beginning, the mathematical model, allocation methods and software tool are presented. In the following, a comparison between the two allocation methods is performed. Three power system operating conditions are analysed. Real large scale case study has been used. It has been modelled based on the Western, South-Western sides of the Romanian Power System. Useful results for interconnection capacities allocated to generators and their related cost have been provided.

8

Authors: GAVRILAS. M., GRIGORAS GH., CAZACU M., CARP C.O., ANDREI I.

The paper presents the results of the implementation of a program for reducing technical active energy losses in the distribution network operated by Delgaz Grid DSO (Distribution System Operator). Measures applied to reduce technical losses addresses both transformers at the MV / LV transformer substations and the LV network power lines. The impact of these measures has been assessed using pilot networks with structures and electrical characteristics known in detail. For the phase load balancing measure two methods have been proposed, one based on a bottom-up constructive approach and the other based on identifying a (sub)optimal solution using meta-heuristic techniques.

6

Authors: VOINA A., OPRINA G., PATRU I., UNGUREANU L.C., STANOI V., PICA A., SERBAN F., LINGVAY I.

The influence on the quality of the electrical insulating fluids on the safety in operation of the transformers has been evaluated. After processing the comparative experimental data obtained by gas chromatography technique on 5 different sorts of electrical insulating fluids (a sort of vegetable oil with high oleic content and with addition of 0.5% antioxidant "functional model" - compared with two commercial sorts of mineral oil, 1 mainly vegetable commercial oil, 1 commercial synthetic ester), thermal aged in contact with electrical insulating paper and copper for electrical use, at 110 ± 3 °C for 1000 hours in closed vessels (limited access to atmospheric oxygen) it has been found that at the transformers filled with mineral oils, the risk of explosion and fire is approx. 10 times higher than those filled with synthetic or vegetal ester. It has also been found that the ageing of the insulation paper is approx. 15 times slower in the synthetic and natural ester than in the mineral oils normally used in transformers.

6

Authors: PANAIT A.

The paper promotes bioliquids from indigenous oil-rich plants as renewable energy sources. In the first part the paper analyzes the national and European perspectives to develop renewable energy sources according to the National Strategy for 2016 -2030 with the prospect of 2050, as per European directives. The second part presents the point of view of the Directive 2009/28/EC on bioliquids and the possibility to use bioliquids from oil-rich plants for energy generation in order to reduce pollutant emissions. The third part of this paper presents the results of laboratory analyses concerning the energy characteristics of bioliquids from indigenous oil-rich plants. The conclusions of part four point out that bioliquids from oil-rich plants have the potential to be a solution for EU’s renewable energy and the climate change objectives.

7

Authors: TABET I., TOUAFEK K., BELLEL N., KHELIFA A., BAISSI M.T.

In this paper, a theoretical and experimental studyof flat platesolar water collector with reflectors.A mathematical model based on energy balance equations saw the thermal behavior of the collector is investigated. The experimental test was made at the unit research applies in renewable energy (URAER) located in southern Algeria.An increase of 23% for solar radiation incident on the collector surface with the addition of the planers reflectors in the day of May, this increase causes an improvement of the performance of the collector,the fluid temperature increases with an average of 5%. Thetests conducted on the flat plate solar water collector in open circuit enabled the determination of thermal performance of the collector by estimating the daily output The thermal efficiency of the collector ranges from 1% -63% during the day, a mean value of 36%obtained.

6

Authors: LINGVAY I., OPRINA G., CUCOȘ A., RADU E., VOINA A.

The By gravimetric measurements and coupled thermal analysis techniques (DTG+TG+DTA) the aging of different sorts of insulating oil was studied by thermal cycling between -400C and 850C. The experimental results showed that, during the thermal cycling of the investigated mineral oils, their composition changes due to the volatilization of the volatile fractions (mass losses between 3.9% and 5.8%), unlike the investigated vegetable oil that showed a mass increase of approx. 0.66%. It has also been found that the mineral oils can be ensure a safe operation, without significant changes up to a maximum of 1000C, as long as investigating vegetable oil can be used without degradation risk up to 2000C.

6

Authors: TOMA R., GAVRILAS M.

The paper presents a comparative study between the effects on voltage stability of the integration of a wind farm into the electricity grid with or without voltage dependent loads in the context of different locations of a synchronous compensator from the grid. The P-V curves are built by using the PowerFactory DigSilent 15.2.2 and a DPL script that implements a simplified form of the Continuation Power Flow method.

8

Authors: OPRINA G., CHIHAIA R.A., EL-LEATHEY L.A., NICOLAIE S., BĂBUȚANU C.A., VOINA A.

On a dynamic energy market characterized by the constant energy demand increase and economic as well as environmental constraints, the study and development of efficient conversion systems of wind’s energy has been approached by a considerable number of researchers. Given the modern economic and environmental challenges regarding the energy production and consumption, an advance in the research of innovative or improved wind energy conversion solutions has been registered. The objective of this paper is to provide a comprehensive, but not exhaustive overview of research achievements in counter-rotating wind turbine systems development, characterization and use. The review presents the first theoretical results that led to the counterrotating wind turbines development as well as the related methods used for investigating their performance. Valuable results have been found within various studies, which are carried out for different testing systems and conditions. Furthermore, there is still need of extensive studies, taking into account that the counter-rotating wind turbines have to prove their reliability in real operating conditions.