Vapor/liquid ratio tests

The vapor/liquid ratio tests measure the amount of vapor formed from a given volume of liquid at a given temperature at atmospheric pressure. A common measure used in specifying gasoline is the temperature at which the vapor/liquid ratio is 20 (TV/,L=20 ). Although V/L can be measured experimentally, it is a difficult and time consuming test to carry out, and techniques have been developed to calculate it from RVP and D86 values. 

Vapor lock protection classes. There are five classes for vapor lock protection. This classification depends on location and/or season. The limit for each class is a maximum vapor-liquid ratio of 20 at one of the specified testing temperatures of41,47, 51,56, or 60°C. 

The test chamber shall be designed to contain between 2 and 50 mL of liquid and vapor and be capable of maintaining a vapor-liquid ratio between 3.95 to 1.00 and... 

Included among the salts chosen for study were those that cause salting-out (NaBr, NaF, KCl, Li Cl) and salting-in (HgC ) of methanol in aqueous solutions. To test the technique described above, the vapor-liquid equilibria of systems of constant ratios of salt to solvent 2 were measured. For example, in cases where methanol is salted out, the experiments were done at constant salt-to-water ratios, and when methanol is salted in (salting-out of water), constant salt-to-methanol ratios were used. This was done by preparing a solution of a fixed salt molality and using it as component 2 in the equilibrium still. Thus, references to molality refer to the ratio moles of salt to 1000 g of solvent 2. 

This case study involves the recovery of highly valued and high demand ethylbenzene (EB) and mixed-xylenes (comprising of p-xylene (PX), m-xylene (MX) and o-xylene (OX)) from a C8-aromatics mixture (C8A). As point out above, C8A is isomers mixture, so their separation (recovery) is not simple, that why there is only one commercial process of liquid-phase adsorptive separation available for EB recovery from C8A. [8] However, this process requires high investment cost and generates huge volume of waste adsorbent that may become an environmental problem. Therefore, another green process should be considered for the EB purification. The ratio of various properties of the key components (EB and PX) were tested to examine the possibly alternatives. The result showed, by vapor pressure ratio, the solvent-based extractive distillation can be employed for their purification. [7]... 

Pervaporation was next carried out to test the selectivity of polyaniline membranes toward acetic acid-water mixtures. Different feed ratios of acetic acid and water were pervaporated through both undoped and doped polyaniline, as shown in Fig. 33.18, where the feed water content is plotted versus the permeant water content. For comparison the vapor-liquid equilibrium curve for acetic acid-water [78] is plotted just above the line of no separation. From Fig. 33.18 it is clear that undoped polyaniline has a small preference for permeating water over acetic acid at essentially any composition. However, this small preference at an average water permeability of about 0.5 g mm/(m--h) is too low to have any utility. More interesting is fully HCl-doped polyaniline, which permeates water over acetic acid in a much more selective fashion. In fact, even with a mixture of 859f acetic acid-15% water, at least 93 wt % of the permeant was water. It should be pointed out that when undoped membranes are used in the presence of acids, they will partially dope the polyaniline, the extent depending on the pH of the acid used. However, when a... 

In this case, q equals the latent heat of vaporization of the test fluid times the weight of the liquid contained between two of the sensing resistors, divided by the time it takes to vaporize this weight of liquid. The effective area, 4, is simply 2 rr times the thickness of insulation times the average height of the liquid, all divided by the natural logarithm of the ratio of the outer to inner radius of the insulation. For test runs where liquid nitrogen is used as the cold bath, the equation reduces to... 

This test method covers the determination of the total pressure of air-containing, volatile, petroleum products. This test method is suitable for testing samples with boiling points above O C (32"F) that exert a vapor pressure between 7 and 172 kPa (1 and 25 psi) at 37.8 C (lOO F) at a vapor-to-liquid ratio of 4 1. This test method is suitable for testing gasoline samples that contain oxygenates. No account is made of dissolved water in the sample. 

Blood alcohol concentration (BAG) is often based not on an actual sample of blood but rather on the concentration of alcohol in a sample of breath (Figure 3.3). Alcohol is volatile, and, as described by Henry s law, there is a constant relationship between the amount of alcohol vapor found in a volume of air (breath sample) and the amount of alcohol found in a volume of liquid (blood). All breath-testing equipment uses the blood-breath ratio of 2,100 1 for alcohol. This means that the amount of alcohol found in 2,100 milliliters of breath is equivalent to the amount of alcohol found in 1 milliliters of blood. 

The universal foam has not been tested in the public arena to the extent that results are available in the literature. Proprietary testing by product users has shown that it is highly effective as a vapor suppressant when used at an expansion ratio of 35-45 1. At this ratio, its expansion was good and its drainage time was 13-15 minutes. This foam has been tested on the following materials with favorable results trichlorosilane, di-methyldichlorosilane, phosphorus trichloride liquid, liquid hydrochloric acid, and titanium tetrachloride. Because of the quick vaporization rate of anhydrous ammonia and chlorine, no foam has been identified to date as being effective for all vapor suppression applications (Chubb National Foam, 1992b). 

Consider a propane concentration of 88 percent in the feed. The McCabe-Thiele diagram, based on the Fig. 7.12a interpretation of the test data, predicts a pinch just below the feed (Fig. 7.12e). Due to the pinch, the concentration of propane in the tower bottom will be 17 percent, i.e,. much higher than the 2 percent propane in the test data. In practice, this pinch will probably be eliminated by increasing the boilup ratio (i.e., reducing the slope of the operating line). However, increasing the boilup ratio means more liquid and vapor traffic, a greater heat load on the reboiler, and possibly, a premature capacity bottleneck. 

This is the philosophy behind the set of experiments currently underway. Fuel properties, equivalence ratio, droplet size distribution, gas-phase composition, liquid-vapor fuel split, prevaporization time, and homogeneity can all be controlled independently. Testing will determine the effect that each of these variables has on detonability and detonation characteristics. 

Plate efficiencies and HETP values are complex functions of measurable physical properties temperature, pressure, composition, density, viscosity, diflusivity, and surface tension measurable hydrodynamic factors pressure drop and liquid and vapor flow rates plus factors that cannot be predicted or measured accurately foaming tendency, liquid and gas turbulence, bubble and droplet sizes, flow oscillations, emulsification, contact time, froth formation, and others. Values for plate efficiency, HETP, or HTU, particularly those that purport to compare various devices, are usually taken over a limited range of concentration and liquid-to-vapor ratios. The crossovers in Fig. 2.5 and the rather strange behavior of the ethyl alcohol-water system, Fig. 2.6, demonstrate the critical need for test data under expected operating conditions. ... 

This report is concerned with contact angle hysteresis and with a closely related quantity referred to as "critical line force (CLF)." More particularly, it is concerned with the relationship between contact angle hysteresis and the magnitude of the contact angle itself. Two sets of liquid-solid-vapor systems have been investigated to provide the experimental data. One set consists of Teflon [poly(tetrafluoroethylene), Du Pont] and a series of liquids forming various contact angles at the Teflon-air interface. The second set consists of polyethylene and a similar series of liquids. In neither case was the ratio of air to test liquid vapor at the boundary line controlled, but it can be assumed that the ambient vapor phase operative in all the systems was close to an equilibrium mixture. 

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