Electrical power conversion

In order to obtain high overall light to electric power conversion efficiencies, optimization of the short circuit photo current (z sc) and open circuit potential (Voc) of the solar cell is essential. The conduction band of the TiC>2 is known to have a Nernstian dependence on pH [55,67]. The fully protonated sensitizer 2, upon adsorption transfers most of its protons to the TiC>2 surface, charging it positively. The electric field associated with the surface dipole generated in this fashion enhances the adsorption of the anionic Ru complex and assists electron injection from the excited state of the sensitizer into the titania conduction band, favoring high photocurrents (18-19 mA cm-2). However, the open-circuit potential (0.65 V) is lower due to the positive shift of the conduction band edge induced by the surface protonation. 

The solar to electric power conversion efficiency of dye-sensitized solar cells of laboratory scale (0.158 cm2), validated by an accredited photovoltaic calibration laboratory, has reached 11.1% under standard reporting conditions, i.e., air mass 1.5 global sunlight at 1000 Wm-2 intensity and 298 K temperature, rendering it a credible alternative to conventional p-n junction photovoltaic devices [68]. Photovoltaic performance data obtained with a sandwich cell under illumination by simulated AM 1.5 solar light using complex 26 are shown in Fig. 16. At 1 sun the 26-sensitized solar cell exhibited 17.73 =b 0.5 mA current, 846 mV potential, and a fill factor of 0.75 yielding an overall conversion efficiency of 11.18%. 

The United States derived about 20 percent of its electricity from nuclear energy in 2002 (EIA, Electric Power Monthly, 2003). The 103 power reactors operating today have a total capacity of nearly 100 gigawatts electric (GWe) and constitute about 13 percent of the installed U.S. electric generation capacity. The current U.S. plants use water as the coolant and neutron moderator (hence called light-water reactors, or LWRs) and rely on the steam Rankine cycle as the thermal-to-electrical power conversion cycle. Other countries use other technologies—notably C02-cooled reactors in the United Kingdom and heavy-water-cooled reactors (HWRs) in Canada and India. 

Power from outside (20MWe) Electric Power Conversion Module in 50%) UoMWt) Pre- Cooler Heat R please (20MWt)... 

Electromagnetic pumps drive the primary coolant circulation. The reactor is coupled to four thermo-electric power conversion segments placed around the reactor, Fig. XVII-1. Each segment has a pumped sodium heat rejection loop. 

Ito S, Murakami TN, Comte P et al (2008) Fabrication of thin film dye sensitized solar cells with solar to electric power conversion efficiency over 10%. Thin Solid Films 516 4613 619... 

Dye-sensitized nanocrystalline Ti02 solar cells are presently under intensive investigation. " So far, the best performing charge transfer sensitizer employed for such an application is the cw-dithiocyanato-bis(4,4 -dicarboxy-2,2 -bipyridi-ne)ruthenium(II) complex, yielding solar-to-electric power conversion efficiency of 10% under standard solar conditions. These cells exhibit a remarkable stability, making practical applications feasible. 

A remarkable advance in the use of organic dyes for DSC was recently made by the group of Arakawa et al. (Hara, 2001, 2002). Using coumarine or polyene type sensitizers, strikingly high solar to electric power conversion efficiencies reaching up to 7.7% in full sunlight have been achieved. 

Because of core/clad interface temperature limitations, the turbine inlet temperature has been established as 900 K. Because a terrestrial location is postulated for this reactor concept, a compressor inlet temperature of 310 K is specified. For simplicity, a forced convection air design was chosen as the ultimate heat sink. The electrical power conversion efficiency for this system, given 500 kW(t), is 28.2%. 

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