Wetted surface area, estimation

The wetted surface area of the 2 m3 reactor during two-phase relief has been estimated as 8.6 m2. This is the full surface area of the bottom and the sides of the reactor because, if two-phase relief occurs, this whole area will be wetted inside the reactor with liquid. The heat input rate from the fire is estimated as 252 kW l For a closed reactor containing 793 kg of material, and using the average, specific heat capacity of 2.25 kJ/kg K, the effective rate of temperature rise due to the fire is given by ... 

The silica release rate and flow-rate mass ratio of Figure 18 depend on estimations of the wetted surface area of reacting minerals and the mass of wetted soil. As discussed by Paces (1983), there is much uncertainty in estimating wetted surface areas of reacting minerals. In Figure 18 and Table 3, it was assumed that 40% of the surface area of soil was weatherable minerals the soil surface area was 0.5 m2 g 1 (except at Coweeta, where Velbel s (1985) procedure was used), the bulk density of the soil was 1.5 kg L-1, and the equivalent saturated water depth was 0.5 m (except at Coweeta and Cristallina, where it was taken to be 0.1 m). All of these parameters were measured at Bear Brook Watershed and applied to the other sites. 

The vessel.exe program has been developed to estimate the total and filled-liq-uid volumes and dry and wet surface areas for horizontal, vertical, and inclined (e.g., slug catcher) vessels. For horizontal and vertical vessels, the program also calculates the weight of the material and the hydro test weight. 

For vapor relief from columns (other than fire relief), the rate of vapor relief and the fluid properties must be determined by simulation at relieving pressure. The relieving will be 110% or 116%, depending on the requirement. For a fire case, the relief rate depends upon the latent heat and wetted surface area. The latent heat shall be estimated at 121% relieving pressure and for the average liquid composition within the column. 

The heat input into a liquid wet vessel depends upon the wetted area of the vessel. The following guidelines are used to estimate the wetted surface area ... 

For the shell side of a shell and tube heat exchanger, the wetted surface area is estimated as follows ... 

Fig. 6. Surface area of coals as estimated from (o) neon sorption at 25°C and (x) methanol heat of wetting.

Immersion calorimetry is a very useful technique for the surface characterization of solids. It has been widely used with for the characterization of microporous solids, mainly microporous carbons [6]. The heat evolved when a given liquid wets a solid can be used to estimate the surface area available for the liquid molecules. Furthermore, specific interactions between the solid surface and the immersion liquid can also be analyzed. The appropriate selection of the immersion liquid can be used to characterize both the textural and the surface chemical properties of porous solids. Additionally, in the case zeolites, the enthalpy of immersion can also be related to the nature of the zeolite framework structure, the type, valence, chemistry and accessibility of the cation, and the extent of ion exchange. This information can be used, together with that provided by other techniques, to have a more complete knowledge of the textural and chemical properties of these materials. 

The properties of active carbon render it a difficult material to use as an electrode. Electrochemical processes occur more often in the inner cavities (pore structure) of active carbon particles than on their outer, planar surface. For this reason, three-dimensional electrochemical activity is observed rather than the planar responses characteristic of solid carbon electrodes. It is generally a.s.sumed that the total area of the internal structure of the porous carbon electrode is completely wetted by electrolyte, although this may not be the case with high-surface-area carbons containing micropores inaccessible to electrolyte. The main difficulty is estimating the electrochemically active part of the total surface area of the active carbon electrode material. 

The adsorption isotherms for hydrocarbons on wet cellulose approach BET type III (1 0 in form as the relative humidity is increased (9.), and the isosteric heats approach the heat of condensation for all surface coverages of hydrocarbon (11 ). Thus, water lowers the affinity of cellulose for hydrocarbons. This effect is independent of any changes in surface area with relative humidity, and is also observed on regenerated cellulose film (12 ). However, the thermodynamic data indicate that the surface does not behave as expected for pure water, even at very high water contents (ll). In fact, the GC method has also been used to study adsorption of hydrocarbons on liquid water (15, l6). In this case, the interactions are very weak and the adsorption isotherm does not fit the BET theory, so that surface areas cannot be estimated directly (16). 

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