Sohd-liquid phase change materials

A further temperature decrease causes two phenomena to take place. First, there is an increase in the quantity of solid phase and a decrease in the quantity of liquid phase. The fluidity of the alloy is reduced and the material takes on the consistency of a paste or mush (i.e., slush) hence, this two-phase region is often referred to as the pasty range or the mushy zone. Second, there is a change in the respective compositions of the Uquid and sohd phases. For example, when the temperature of the alloy drops to that of point C, 195 ° C, the composition of the newly formed... 

Adsorption is the process whereby molecules of a gas or liquid species adhere to a solid surface. If a certain species A has a greater affinity for the solid surface than another species B in the mixture the preferentially adsorbed species can in principle be separated from the other molecules in the gas or Hquid mixture. If the solid adsorbent is to be reused the adsorbed species must be desorbed from the solid. In gas phase adsorption the adsorbed material is most often removed by changing the temperature and/or the pressure of the system along with a carrier or sweeper gas. For liquid systems a chemical desorbent must be found that preferentially displaces the desired product species from the soHd. The desorbent must itself be easily separated from the product in another separation step, usually distillation. 

A phase is the entirety of regions, where material properties either do not change or only change continually, but never change abmptly. However, it makes no difference whether the regions are spatially coherent or not (continuous or dispersed phase). A phase can consist of one or more chemically uniform substances, which are called components. A system can contain one phase (gas, liquid, solid), two phases (e.g., liquid/gas, fluid/sohd, fluid/fluid), or even more (in an evaporative crystallizer, e.g., there are a solid, a liquid and a gaseous phase) This chapter describes the thermo namic equilibrium between phases. 

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