Water transport, liquid-solid systems drying

Batteries that require a liquid electrolyte are called wet batteries. Corrosive battery fluid refers to either acid electrolytes syn. battery acid, like the common lead-acid automobile battery which uses a solution of sulphuric acid, or alkali electrolytes syn. alkaline corrosive battery fluid, like potassium hydroxide (1310-58-3) solutions in nickel-cadmium and other alkaline battery systems. Dry batteries or dry cells, like all primary batteries, use electrolytes immobilized in pastes, gels, or absorbed into separator materials. Some batteries are loaded with a dry, solid chemical (e.g., potassium hydroxide) which is diluted with water to become a liquid electrolyte. The hazards associated with handling and transportation prior to use are thereby reduced. 

Movements of liquid water within porous solids have been experimentally observed. Haines studied the movement of liquid water within porous media during drying [26, 27]. He observed rapid movements of water elements in the porous system (Haines jumps). The capillary pressure transports water to narrow pores at the surface. Larger volumes surrounded by narrow pores can be rapidly emptied, and smaller volumes can be filled when the water is removed out of the narrow... 

Large quantities of water are required for the production of most plant materials. For example, several hundred kg of water are required to produce one kg of dry hay. Water is part of the three-phase, solid-liquid-gas system making up soil. It is the basic transport medium for carrying essential plant nutrients from solid soil particles into plant roots and to the farthest reaches of the plant s leaf structure (Figure 18.3). The water enters the atmosphere from the plant s leaves, a process called transpiration. 

During the drying phase energy is transported into the solid by heat conduction. Due to the temperature profile caused by the specific characteristics of the system the water that is contained in the solid is not evaporated uniformly allover the particle radius. On the contrary, a steep drying front will be formed which moves towards the particle center. The water content per unit volume above the fiber saturation point (FSP) is called free liquid water whereas the water content below this point refers to bound liquid water . The bound liquid water can be regarded as an adsorbed phase. The transport and evaporation characteristics of the liquid water strongly change at the FSP. Below the FSP the transport mechanism is similar to a diffusion process whereas above the FSP the liquid water is transported due to... 

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