Journal of Sustainable Energy

6

Authors: CIOBANU A., MUNTEANU F., NEMES C, ADOCHITEI M.

The authors present a Bayesian network capable to estimate the weather parameters related, not only, to renewable resources: wind speed and solar irradiation. A large and systematic data base about simple and composed weather indices registered during four years, 2013-2016, was used to construct the data-driven Bayesian structure and to learn and validate its parameters. It includes 9 weather indices collected, minute by minute, by a professional Davis Instrument Pro 2 Plus weather station. The extremely large initial data base, over 1.8 million records, was discretized in 4 classes making possible to use a very simple algorithm like Bayesian search to establish the most suitable network structure fitting the data. The main and first useful results mean the probability of wind speed and solar irradiance classes. Both parameters can be transformed in electrical power considering a given wind generator and a solar panel.

6

Authors: DINU R.C., POPESCU D., STAN – IVAN F. E.

Thermal energy consumers that provide comfort parameters inside buildings and, in particular, domestic consumers assigned to a centralized heat supply system, are currently affected by the high level of thermal losses on the transport and distribution networks of the heat at source of the actual consuming installations. These losses are incurred to a large extent by consumers and, to a lesser extent, by the heat distributor, which makes the price of heating energy to reach in some localities on the territory of Romania, prohibitive values. This paper presents a study regarding the financial effects of the thermal rehabilitation of a pipeline section for the transport of the heating agent for heating, through the choice of a suitable thermal insulation of the pipes, in order to reduce the heat loss to the external environment.

8

Authors: IAS G.I., LOLEA M.S., MINDA A.A

The paper relates to the analysis of the local RES potential for the installation of power plants to allow for the extension of the regional power system for a site located in the southern part of the Bihor county, in the perimeter and the vicinity of the cities of Vaşcău, Nucet and Ştei. There are highlighted aspects of the current state of regional valorisation of renewable energy resources and possibilities for interconnection and connection to the Power System (PWS), for the optimal supply of electricity to consumers. A comparative analysis of the advantages and impediments generated by the implementation of local energy projects based on RES, focusing especially on wind energy, is developed and presented. At the end of the paper are presented the recommendations regarding the opportunity of using the RES and conclusions resulting from the study underlying that work.

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.