Soaking temperature rise

Heat generation during the soaking step is proportional to the specific surface of the cured paste [14]. Thus, the temperature rise on soaking of 4BS pastes is half that for 3BS pastes. It is therefore not necessary to cool down the H2SO4 solution before filling into batteries with 4BS cured plates. 

For a typical bulk polymerization 4.80 g of PEG 600,4.24 g of DEG, and 8.07 g of HMDI were placed in a 100 mL flask and heated to 50°C while purging continuously with nitrogen. 10 mg of dibutyltin bis-(2-ethylhexanoate) was dissolved in 7 mL of 4-methyl-2-pentanone and added to the warm reaction mixture. The reaction quickly became exothermic, widi the temperature rising to 100 C within a few minutes. When the reaction cooled to 90°C, heating was resumed to maintain that temperature for another 60 min. The polymer was dissolved in 200 mL of 90 C DMF. When the polymer solution had cooled to room temperature, it was poured into 2 L of vigorously stirred deionized water to precipitate the polymer. The precipitated polymer was tom into small pieces and soaked in deionized water for 24 hours, with several water changes. The polymer was dried in vacuo at 50°C. 

Microporous polyethylene separator and the matrix polymer were soaked in the electrolyte solution and they were heated at various temperatures for 60 minutes. The vapor amounts from both samples were measured and compared. The result is shown in Figure 6 and it is clearly seen in this figure that vapor pressure of solvents in Sony GPE is significantly low even at high temperature like 100 °C, while microporous separator can hold the solution at low temperature probably due to large surface tension in the micropores but vaporization of solvents increase steeply as temperature rises. 

The time, A t, required for the temperature of 2 cm of the oil-soaked adsorbent cotton charged in the draft cell, into which air is supplied, and subjected to the adiabatic oxidatively-heating test started from a T, below about 180 °C to increase by the definite value of A T oi 1.25 K from the corresponding standard temperature is determined on the linearly-rising part of the oxidatively-heating process or curve of the substance. 

Since the reactions during the soaking procedure are exothermic, the temperature in the tank or battery starts to rise. The electrochemical reactions involved in the formation process also contribute to the overall thermal balance (in the battery or in the tank). These reactions are endothermic and can be represented by the following equations ... 

Both steps 3 and 4, can be carried out in the same kiln/reactor and no cooling down is necessary between steps. Soaking times at these two temperatures are around 1 hour for each. Compared with carbons produced by thermal activation, the wood-based carbons activated with H3PO4 have a lower density, lower abrasion resistance and a more developed mesoporosity. These properties are related to the hollow fibrous structure of wood, which gives rise to an important macropore volume in the activated carbons. 

In tank formation, the tank full of electrolyte has great heat capacity, so substantial amount of heat has to be generated for the temperature in the tank to rise (Fig. 12.1). This is not the case with container formation, however. There is a small volume of electrolyte in the battery and hence the latter s heat capacity is small. The heat capacity of a system is the measure of the heat energy required to increase the temperature of the system by 1 °C. The heat capacity of 1 g of mass is called specific heat. The electrolyte has the highest specific heat as compared to the specific heats of the other battery components. During soaking, the temperature in the battery increases rapidly... 

With a heat zone longitudinally top fired, the burner wall temperature would be 100°F (56°C) above the product discharge temperature and 100°F below the peak temperature of the zone at high fire. With side firing, the heat zone curve raises the zone entering temperature quickly to a peak of 2340 F (1280 C). The heat zone temperature then falls with greater slope than the soak zone to 2180 F (1193 C) just before the preheat zone starts to rise to a maximum of 2180 F (1193 C). 

The shape is normally produced by pressing. Bridging of powders during die filling and friction between the die wall and punches give rise to nonuniform density. Friction is reduced by the use of a die wall or admixed lubricant. In the case of admixed lubricants, a low temperature soaking is needed to remove the lubricant. Admixed powders are useful for automatic compaction. 

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