No-flow condition

Operation of this cooling water system was intermittent, resulting in long periods (30 days) of no-flow conditions. After IVi years, leaks were found at welded pipe junctions. Radiographic examinations revealed numerous additional deep corrosion sites at welds that had not yet begun to leak. 

Overpressure and tube failure may also result from valve closure on the inlet side of a fomace, or from feed pump failure, etc, if the coil remains pressurized by downstream equipment. In these cases, however, overpressure occurs at or below the normal operating pressure (due to overheating at no-flow conditions), and a PR valve cannot provide the necessary protection. 

Most research has been performed in a two-phase medium with no flow conditions very little has been done in two-phase-flow systems. Although the flow condition may bring in new variables, such as slip ratio, it is reasonable to assume that the basic phenomena observed in the nonflow condition also occur in the flow condition. 

We report here, for the first time, that hydrodynamic forces can dramatically Increase the rate of desorption in polymer systems which are otherwise irreversibly adsorbed under no-flow conditions. Indeed, at high enough shear stresses, complete removal of the polymer is possible. The technique of ellipsometry is well suited for this problem as simultaneous measurements of both film thickness and adsorbance are possible during the flow process. 

Backpressure The pressure existing at the outlet of a relief device. The value under no-flow conditions is superimposed backpressure. The value under flowing conditions consists of both... 

The outlet size required to overcome no-flow conditions depends highly on the flow pattern that develops. If mass flow develops, the minimum outlet diameter. Be, to overcome arching is (4) ... 

Erratic Flow. A combination of the two no-flow conditions can lead to erratic flow. If flow has been initiated but a stable rathole develops, then when the rathole collapses using vibration, the material may arch as it impacts the outlet. Flow may be restarted by vibration and maintained for a short time until the rathole forms again. Erratic flow can be a serious problem when handling bulk solids owing to fluctuating flow rates and bulk densities, and unreliable discharge. It can also jeopardize the structural integrity of the bin when a rathole collapses. 

A two-dimensional example problem is also developed to demonstrate the advective control model. The example problem is solved for both confined and unconfined conditions and the solutions are compared. In this example problem, the aquifer is homogeneous and isotropic, with no flow conditions imposed at the top and bottom boundaries and constant head conditions along the left and right boundaries. The head on the constant head boundaries slopes downward toward the bottom of the domain. The domain is 3100 m by 3100 m and is discretized into 49 rows and 58 columns. A river runs through the domain as shown in Figure 6. 

Three 1-D column studies were conducted to investigate the effects of EtOH addition (0, 5, and 10% wt) on the micellar solubilization of residual PCE by 4% Tween 80 in a uniform porous medium. The applied Darcy velocities ranged from 3. 3 to 4.9 cm/hr. Periods of flow interruption (8 and 15 hours) were utilized to evaluate PCE mass transfer under no flow conditions. A summary of the experimental conditions and physical... 

In this study, the effects of cosolvent (EtOH) addition on the solubilization and recovery of PCE by a nonionic surfactant (Tween 80) was evaluated using a combination of batch, column and 2-D box studies. Batch results demonstrated that the addition of 5% and 10% EtOH increased the solubilization capacity of Tween 80 from 0.69 g PCE/g surfactant to 1.09 g PCE/g surfactant. For a 4% Tween 80 solution, this translates into a solubility enhancement of more than 50%, from 26,900 mg/L to 42,300. mg/L. When the surfactant formulations were flushed through soil columns containing residual PCE, effluent concentration data clearly showed that PCE solubilization was rate-limited, regardless of the EtOH concentration. Using analytical solutions to the 1-D ADR equation, effective mass transfer coefficients (Ke) were obtained from the effluent concentration data for both steady-state (A e ) and no flow conditions The addition of EtOH had... 

Under no-flow conditions where sufficient time had passed to establish chemical equilibrium, the right-hand side of Eqs. (9.5)-(9.8) would equal zero and could be solved simultaneously to provide a relationship between the total sorbed quantity q of phosphorus and the concentration A of water-soluble phosphorus. For the linear case where the order of the reaction n = 1, the relationship is... 

The application of a flow field has pronounced effects on the crystallization dynamics and semi-crystalline morphology of polymeric systems. Under quiescent, no-flow conditions the crystallization dynamics is governed by the temperature, T, and spherulites are formed. In the presence of flow, increasing the flow rate can result in an increase of the nuclei density up to factors of 106, but the morphology remains spherulitic [18]. At even higher flow rates the so-called shish-kebab morphology is observed. This results from the de-... 

Various quantiiics associated with a mixture of two species A and fi at a location x under one-dimensional How or no-flow conditions. (The density of the mixture p - + p is assumed to remain constant.)... 

The forward problem involves numerically solving Eqs (45) and (46) along with appropriate boundary conditions. Boundary conditions associated with velocity field v correspond to no-flow conditions on the transverse sides. 

In the case of a viscous flow, on the surface of the particle we have either the no-slip condition (for a solid particle) or the no-flow condition (for a fluid particle) therefore, one can represent the stream function in the form... 

By (5.9.20), the no-slip and no-flow conditions hold on the hard surface, and a linear temperature distribution is maintained. Condition (5.9.21) says that the no-flow condition on the free surface and the condition of zero heat flux through the free surface must hold, and the balance of tangential thermocapillary and viscous stresses must be provided. Taking into account the quadratic dependence (5.9.19) of the surface tension on temperature, we rewrite the right-hand side of the last condition in (5.9.21) using the relation... 

We now consider the hydrodynamic part of the problem, which is described by the Stokes equations (2.1.2). The fluid velocity components satisfy (2.2.2) remote from the drop, and the solution is bounded within the drop. On the interface, the no-flow condition (2.2.6) holds and condition (2.2.7) of continuity of the tangential velocity component must be satisfied. Moreover, the boundary condition of the tangential stress balance is to be used ... 

Plate 3. DIC of the etch pits resulting from the dissolution of a calcite uema maleic acid for 15 min under no-flow conditions. The u... 

The upper boundary has a prescribed total water head of 0.8MPa and the other boundaries are set at no flow condition. The mechanical boundary condition was a roller condition for all boundaries. The intact rock mechanical properties were similar to... 

Influence of boundary condition Two kinds of hydraulic boundary conditions are tested. The first one supposes an impermeable tunnel wall, the second a prescribed relative humidity (HR). Figure 8 shows that the assumption is very influent close to the wall (first 15 cm). The mechanical consequence of this low saturation level is an important increase of suction so that plasticity never occurs. In conclusion, imposed HR is not suitable for elastoplastic model using Bishop s effective stresses. Thus, no flow condition has been adopted. 

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