Injection constant pressure

Example 5.13 Derive an expression for the flow length of a power law fluid when it is injected at constant pressure into a rectangular section channel assuming... 

A power law plastic is injected into a circular section channel using a constant pressure, P. Derive an expression for the flow length assuming that... 

A polymer melt is injected into a circular section channel under constant pressure. What is the ratio of the maximum non-isothermal flow length to the isothermal flow length in the same time for (a) a Newtonian melt and (b) a power law melt with index, n = 0.3. 

A group of chemistry students have injected 46.2 g of a gas into an evacuated, constant-volume container at 27°C and atmospheric pressure. Now the students want to heat the gas at constant pressure by allowing some of the gas to escape during the heating. What mass of gas must be released if the temperature is raised to 327°C ... 

Since all electrophoretic mobility values are proportional to the reciprocal viscosity of the buffer, as derived in Chapter 1, the experimental mobility values n must be normalized to the same buffer viscosity to eliminate all other influences on the experimental data besides the association equilibrium. Some commercial capillary zone electrophoresis (CZE) instruments allow the application of a constant pressure to the capillary. With such an instrument the viscosity of the buffer can be determined by injecting a neutral marker into the buffer and then calculating the viscosity from the time that the marker needs to travel through the capillary at a set pressure. During this experiment the high voltage is switched off. 

Fig. 12.2 Bubble volume as a function of flow rate for air injection into water at 20°C. Curves for constant flow obtained from Ruff model, Eqs. (12-10) to (12-12) (1) d r = 0.63 cm, fi = 1.5 x 10 (2) dor = 0.32 cm, fj. = 2A x 10 . Experimental results shown for constant flow, intermediate, and constant pressure conditions.

Consider a straight tubular runner of length L. A melt following the power-law model is injected at constant pressure into the runner. The melt front progresses along the runner until it reaches the gate located at its end. Calculate the melt front position, Z(f), and the instantaneous flow rate, Q t), as a function of time. Assume an incompressible fluid and an isothermal and fully developed flow, and make use of the pseudo-steady-state approximation. For a polymer melt with K = 2.18 x 10 N s"/m and n = 0.39, calculate Z(t) and Q(t)... 

Equipment. A LDC (Laboratory Data Control) Constametric III pump was used together with a Rheodyne 7120 20 yl loop injection valve and two LDC Spectromonitor III, variable wavelength UV-detectors. A Stanstead constant pressure pump was used for packing the columns. 

We use a GC Top 8000 gas chromatograph coupled with a PolarisQ ion-trap mass spectrometer and equipped with an AI3000S autosampler (Thermofinnigan www. thermo.com). The steroids are separated on a DB-1 crosslinked methyl-silicone column, 15 mx 0.25 mm i.d., film thickness 0.25 pm (J W Scientific marketed by Agilent). Helium is used as a carrier gas at a constant pressure of about 35 kPa. A 1-pl aliquot of the final derivatized extract is injected into the system operated in splitless mode (valve opened at 2 min). The GC temperature program is the same described before for the quadrupole GC-MS system. The injector and transfer lines are kept at 260°C and 280°C, respectively. The ion source temperature is 225°C. A damping gas flow of helium is applied to the ion trap. 

Figure 2-5A shows the cell full of liquid at temperature T, which is less than the vapor-pressure temperature of the substance. In Figure 2-5B, the substance has been heated at constant pressure to the vapor-pressure temperature. The injection of heat has caused the kinetic energy of the molecules to increase so that the molecules with the highest kinetic energy can escape the attractive forces to form a gas. Gas and liquid coexist. 

The stop-flow technique is the simplest and least expensive method of injection. The flow of the mobile phase is first stopped, either by turning an on—off valve in the line before the column (with constant-pressure systems), or by stopping the pump (with constant-flow systems). The column then returns rapidly to atmospheric pressure, and the sample can be injected directly on to the column with a normal low-pressure syringe. 

P 66] Equal streams of 1 mM solutions of fluorescein-labeled polymer (polyethylen-imine, molecular weight 500 000) in water-glycerol mixtures (0 and 80% glycerol) and a clear solution were injected into the channel [44], The flow was achieved by compressed air at constant pressure. Imaging was achieved by applying a confocal fluorescence microscope. 

The hydrogenation reactions were carried out in a 100-ml stainless-steel autoclave equipped with a 50-ml glass liner and PTFE cover to provide clean conditions. The reactor was magnetically stirred (n = 1000 min 1). The pressure was held at a constant value by a computerized constant volume - constant pressure equipment (Buchi BPC 9901). By monitoring the pressure inside the vessel and the injected pulses, the hydrogen uptake could be followed. Under standard conditions, 42 2 mg prereduced catalyst, 1.84 mmol substrate, 6.8 imol modifier and 5 ml solvent were used at 10 bar and room temperature. 

In this connection, a series of steady state displacement tests were conducted in a 170-200 mesh bead pack with a porosity of 0.4 and an absolute permeability of 7000 md. The experimental apparatus is shown in Figure 7. Two types of gas injection were employed - constant pressure injection and constant rate injection air was used in the former, nitrogen in the latter. The liquid phase was water plus surfactant (0.25% by volume Amphosal CA, Stepan Chemical Company) and was always injected under constant... 

For the injection, a modified Ruska pump was used. The body of the pump was manufactured by the Ruska Instrument Company of Houston, Texas. It is equipped with an electronically controlled drive train developed at New Mexico State University. It can be controlled to run in either a constant rate, a constant pressure or a constant differential pressure mode. 

These experiments were conducted at constant flow rate. Blocking effects at constant pressure (more similar to field conditions) would probably show more dramatic effect. In all of the experiments with injected emulsions, the effective permeability to water was decreased far more than an equivalent amount of residual... 

Reaction or catalytic coke Can be measured properly in MST if a constant pressure profile is maintained. This can be achieved by using a constant catalyst bed height and constant feed injection flow rate. 

---