vahid niksima; kamran lari; masoud torabiazad
Volume 4, Issue 1 , February 2014, , Pages 7-14
Abstract
Nowadays, in consideration of environmental issues and limitation of fossil fuels, there is a particular consideration of renewable energy including Ocean Energy, that can extracted going through various methods such as Wave Energy, Tidal Energy, Salinity Gradient, OTEC: Ocean Thermal Energy Conversion.Herein ...
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Nowadays, in consideration of environmental issues and limitation of fossil fuels, there is a particular consideration of renewable energy including Ocean Energy, that can extracted going through various methods such as Wave Energy, Tidal Energy, Salinity Gradient, OTEC: Ocean Thermal Energy Conversion.Herein this research, operation of OTEC Method in Southern Caspian Sea has been discussed. For this purpose Sea Surface Temperature (SST) Data and Thermocline diagram with respect to 25 stations from east to west coastal area, measured in 1995 in various seasons, have been used. Considering the researches conducted, in order to use OTEC, there must be a difference in temperature between the surface and depth for at least 20 Degrees Centigrade. If such difference in temperature occurs in less depth, closer to the coast, such energy extraction will be more cost-effective.According to investigations conducted, there is a difference in temperature for about 20 Degrees Centigrade in the depth of about 200 m in the Caspian Sea during hot seasons of the year. In summer and early autumn when Thermocline achieves its complete growth, energy extraction from OTEC has a desirable yield. During winter and spring when there is decay in Thermocline, the yield is so low that using this method is not justifiable. Thus, this method can only be used in hot seasons of the year. Finally, hydrographic and temperature investigations have revealed that southeastern coasts especially those of Bandar Neka and Babolsar achieve the desirable difference in temperature, closer to the coast due to high SST and coastal slope, compared to other areas and eventually, using OTECT is cost-effective.
A. A. Bidokhti; A. Shekarbaghani
Volume 1, Issue 1 , December 2011, , Pages 13-22
Abstract
Ocean waters often show layered structures especially where exchange flow between two basins occurs. These structures are often attributed to processes such as double.diffusive convection, internal waves, turbulent modulated mixing. In this paper by examining the vertical structures of temperature, salinity ...
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Ocean waters often show layered structures especially where exchange flow between two basins occurs. These structures are often attributed to processes such as double.diffusive convection, internal waves, turbulent modulated mixing. In this paper by examining the vertical structures of temperature, salinity and density, of the middle parts of Caspian Sea it is shown that such layered structure may be due to the normal modes of the internal waves as double diffusive convection (the density ratio is often negative) does not often occur in these waters. Contours of isotherm, isohaline and isopycnal show the existence of rather regular wavy structures, which may indicate that internal waves, which are produced of exchange, flow between two basins; as a result of horizontal density gradients (usually from middle basin to southern basin) may generate these layers. The flow velocity associated with this gravity driven flow is about 0.1 to 0.15 m/s which gives a Froude number of about one. The wave lengths of these wavy structures are about 200 km and hence, the frequencies of them are of order of inertial frequency at these latitudes. The normal modes of these waves appear to have a near steady structure and can fold the inflow front from the Northern
part of the Caspian Sea to the Southern deep basin. The thickness of formed layers is found be about 10-20 m which is
in agreement with the values predicted by the model of
Wong et al. (2001)
and is less likely to be produced by double
diffusive convection as the density ratio is often not appropriate for this process.