Air al

Problems of the metal-air batteries and air electrode are considered. Results of research, design work and development of the air - Zn primary and air-Al mechanically rechargeable batteries, as well as electrically rechargeable electrodes are presented. 

Air-Al batteries with saline electrolyte (NaCl solution) are simple in maintenance and low cost [4, 7, 19, 20],... 

Chloride-ions participate in the anodic processes. Activation of A1 by Cl" and pH decrease accelerate anodic dissolution of Al. At the cathodic department concentration of OH" increases, and as a result the complex ions, e.g. [Al(OH)4]", are formed. In solution more complicated ions can be formed, for example [Al(OH)xCly]. With the chloride concentration increase, share of hydroxide ions in the complex ions decreases and pH solution grows, as it was shown in our experiments [7, 20], The dependence of voltage of air-Al cell on NaCl concentration has a maximum at concentration of 15wt%. That type of dependence is connected mainly with influence of NaCl concentration on the anodic polarization. For our batteries we choose 15wt% solution of NaCl. Reaction products are most of all are in the colloidal condition. Experiments show that in non-stirred solution it is possible to receive an energy density of up to lOOAh/liter. Intensive stirring increases said performance parameter. 

Figure 2. Volt - amperic curves of an air-Al cell with NaCl solution at 20°C.

Table 4. Parameters of some air-Al batteries with saline electrolyte. 

Air-Zn primary and air A1 mechanically rechargeable batteries with carbonaceous air electrodes were designed and tested. Air Zn batteries are mostly used in the hearing aids, while air-Al batteries find wider range of applications in the portable devices. Electrically rechargeable air electrodes with pyropolymer catalyst have been developed. 

Voligova I.V., Korovin N.V., Kleimenov B.V., Dyachkov E.V. Air-Al batteries with saline electrolyte. In Fundamental problems of electrochemical power sources (FPEPS), I Kasarinov, ed. Saratov SGU, 1999, 169. 

Beryllium interacts with most gases. Polished beryllium surfaces retain llteir brilliance for years on exposure to air al ambient temperatures. The oxidation rate in air increases parabolically at temperatures above 850°C with the formation of a loosely adherent, white oxide. 

Figurel3.20 The experimental transmission spectra of air / Al / PMMA / Al / ZnO / substrate for different PMMA thickness [45].

Figure 13.21 The a) backward and b) forward PL spectra air / Al / PMMA / Al / ZnO / substrate for different PMMA thickness. The spectra of bare ZnO are also shown, c) The plots of forward to backward emission intensity ratio (If / Ib) (square) and transmission (circle) of air / Al / PMMA / Al / ZnO / substrate with PMMA thickness [45].

Figure 5,7. EPR spectrum ai 77 K of a Cu0 /Ce02 calcined in dry air al 1073 K. showing well-resolved features of a dimer species (from ref. [68])...

Fur heal transfer purposes, a standing man can be modeled as a 30 Cm diameier, 170 cm-loag vertical cylinder with both the top and botiom surfaces insulared and with the side surface at an average temperature of 34"C. For a convection heat transfer coefficient of 15 W/m "C, deiemiine the rale of heat loss from ihis man by convection in still air al 20°C. What would your answer be if the convection heal transfer coefficient is Increased to 50 W/m °C as a result of winds What is the wind-chill factor in this case Ansuers 336 W, 11 0 W, 3 .7 C... 

Hot water at 90°C enters a 15-m section ofa cast iron pipe (k = 52 W/m °C) whose inner and outer diameleis arc 4 and 4,6 cm, respectively, at an average velocity of 1.2 m/s.Tlie outer snrface of the pipe, whose emissivily is 0.7, is exposed to the cold air al 10°C in a basement, with a convection heal transfer coefficient of 12 W/ni C. Taking the walls of Ihe basement to be at 10°C also, determine (a) the rate of heat loss from tile water and (f>) the temperature at which the water leaves Uie basement. 

Air al 110°C enters an 18-cin-diaineter and 9-m-long duct at a velocity of 3 m/s. The duct is observed to be nearly isothermal at 85°C. The rate of heat loss from the air in the duct is... 

Thermal energy generated by the electrical resistance of a 5-mm-diameter and 4-m-long bare cable is dissipated to the surrounding air al 20°C. The voltage drop and the electric current across Ihe cable in steady operation ate measured to be 60 V and 1.5 A, respectively. Disregarding radiation, estimate the surface temperature of the cable. 

Air al 25. 1 atru, and 30 percent relative humidity is blown over the surface of a 35-cm X 35-cni square pan filled with water at a free stream velocity of 3 m/s. If the water is maintained at a uniform temperature of 25°C, delermine the rate of evaporation of water and the amount of heal that needs to be supplied to the water to maintain its temperature constant. 

MCM-41, synthesized using hexadecyltrimethylammonium hydroxide, was ion-exchanged with tetrapropylammonium hydroxidc-MCM-41 by shaking a suspension of 2.00 g of MCM-41 in 1.22 g of 25.0 wt. % of tetrapropylammonium hydroxide solution in 1 L at room temperature overnight. The solid was recovered by centrifugation, washed in water and subjected to a hydrothermal treatment at 170°C in a 15-mL Teflon autoclave. The recrystallized MCM-41 was recovered by centrifugation, washed with deionized water and dried under vacuum at 60 °C. The template was removed by calcination in a stream of air al 500 °C for 6 h [91]. 

Values of 0 for water drops falling through air al their terminal velocity are shown in Fig. 6.4-10 for several heights as a function or drop diameter. Calven el al.13 have calculated kLa using the above equations together with calculated values for o , the surface area per unit weight or water, to produce Fig. 6.4-11. A representative value of diffusivity, Ol, of 2 X 10 em /s at 25°C was used for the calculations on which the plot is based. 

Trivalent neptunium is stable only in the absence of oxygen, being oxidized to Np(IV) in aqueous solutions exposed to air [Al ]. 

As nearly ideal substrates, metal physical vapor deposition (PVD) coatings (ca. 100 nm of Au, Al, or Cu) on silicon wafers are used, thus providing not only a very fiat and smooth topography with roughness rpMs < 1-5 nm but also guaranteeing a chemically very well-defined metal surface with native (hydr)oxide. After PVD, metal substrates are stored in dried air (Al one day, Cu four days, Au some weeks) unless otherwise specified. 

Nanopartide Controllable Assembly, Fig. 8 Three diffm nt types of freestanding LBL nanostructures, (a) LBL structures in air al) microcantilever, (a2) miCTotu-bule, o3) hollow microcapsule, and ia4) thin planar film, (b) LBL structures at the air/liquid interface (W) LBL... 

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