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.