Apparent liquid density: defined

Any of the three particle densities defined above should not be confused with bulk density of materials, which includes the voids between the particles in the volume measured. The different values of particle density can be also expressed in a dimensionless form, as relative density, or specific gravity, which is simply the ratio of the density of the particle to the density of water. It is easy to determine the mass of particles accurately but difficult to evaluate their volume because they have irregular shapes and voids between them. The apparent particle density, or if the particles have no closed pores also the true density, can be measured by fluid displacement methods, that is, pycnometry, which are in common use in industry. The displacement can be carried out using either a liquid or a gas, with the gas employed normally being air. Thus, the two known techniques to determine true or apparent density, when applicable, are liquid pycnometry and air pycnometry. 

The buoyancy method relies on weighing the sample in air, wa and in a wettable liquid, wn> e.g. water of density pn. The weight of liquid displaced due to the volume of the sample is given by uynj = wa - wn and the apparent solid density1) ps, is then defined by equation 1 9... 

Figure 10 presents the interface shape of the rivulet for wall superheat as 0.5 K and Re = 2.5. Here also presented the data on pressure in liquid and heat flux density in rivulet cross-section. The intensive liquid evaporation in near contact line region causes the interface deformation. As a result the transversal pressure gradient creates the capillarity induced liquid cross flow in direction to contact line. Finally the balance of evaporated liquid and been bring by capillarity is established. This balance defines the interface shape and apparent contact angle value.For the inertia flow model, the solution is obtained from a non-stationary system of equations, i.e., it is time-dependable. In this case the disturbances in flow interface can create the wave flow patterns. The solutions of unsteady state liquid spreading on heat transfer surface without and with evaporation are presented on Fig. 11. When the evaporation is not included (for zero wall superheat) the wave pattern appears on the interface. When the evaporation includes, the apparent contact angle increase immediately and deform the interface. It causes the wave suppression due to increasing of the film curvature.

A cellular plastic is defined as a two-phase gas-solid plastic system whose apparent density is decreased substantially by the presence of numerous cells or voids disposed throughout its mass. These cells or voids are chiefly formed by using CBAs, PBAs, microballoons, or fillers containing gases or liquids. If these cells are discrete and the gas phase of each is independent of that of the other cells, the material is termed closed cell. 

At the molecular level, what are the differences between the various forms of ice Figure 6.7 shows the experimental crystal structures of normal ice (ice 1) and ice as it exists at about 10,000 atm pressure and a temperature of — 150°C (ice XV). It should be obvious from the two crystal structures that they are different The atoms and molecules are in different orientations with respect to each other, which is what defines a different solid phase. These solid phases have different physical properties, some of which—like melting point—are apparent from the phase diagram. Others are not so apparent. For example, the density of ice IX, which exists at around a pressure of 120 atm and a temperature of 150 K, is about 1.16 g/mL, about 26% higher than normal ice (and hence would sink, not float, in liquid water ). 

The apparent density of a coal particle is the key figure for determination of particle entrainment or fluidization. Experimentally, it is determined by immersing a defined mass of coal in a liquid that does not penetrate the pores of the coal. The accurate measurement of the liquid displaced (pyknometer method) results in the desired volume. From the pure solid volume of the coal HsoUd and the porous volume Hporous, the particle porosity ep is calculated, representing the fraction (or percentage) of the volume occupied by the pores typically ranging from 0.05 to 0.2 [10]. 

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