Flow velocity reduced

It was observed that hydrodynamics plays an important role in circulation time (Table 1). The increase in flow velocity reduces t. It is important to note in Table 1 that both techniques resulted in similar values for for Newtonian and non-Newtonian fluids. Taking the tc obtained by the tracer method as reference, the difference with 4 by thermal method ranges from 11 to 25%. Table 1 shows that depends on flow properties as flow index reduces, increasing at the same time the consistence index, tc increases. 

From (19.31), it follows that an increase in the flow velocity reduces the minimum radius of droplets that can be captured, and thereby increases the capture efficiency (CE) of the string droplet catcher. On the other hand, an increase in the flow velocity can destabilize the liquid film formed on the string surface, stripping drops away from the surface, and thus, reducing the CE. 

I ve read about the importance of shell-side cross-flow in heat-exchanger design books. Higher cross-flow velocities reduce film resistance and promote increased heat-transfer rates. Recently, I had a dramatic personal experience to support this engineering principle. 

When a gas or liquid flows over a surface, the pressure at the surface is reduced according to the formula shown in equation (1), in which d is the density and v is the linear flow velocity of the moving stream. 

Feed or withdraw from both ends, reducing the pipe flow velocity head and required hole pressure drop by a factor of 4. 

Reduce linear flow velocities to eliminate static charge buildup during feed... 

Reduce rate of charging such as by decreasing flow velocity. 

Generally, size exclusion chromatography is carried out using columns with an internal diameter of 7.8 mm. However, some SEC applications require the use of expensive solvents. For this purpose, size exclusion columns with a smaller internal diameter (4.6 mm) have been developed. Of course one should use proportionally lower flow rates with narrow-bore columns. If the standard column size uses a flow rate of 1 ml/min, then the smaller 4.6-mm columns should be used at a flow rate of 0.35 ml/min. This provides the same linear velocity as 1 ml/min on 7.8-mm columns. The decreased flow rate reduces solvent consumption and solvent disposal cost. The performance of the smaller diameter columns is not compromised if properly optimized instrumentation is used. 

All flowing gases and vapors (compressible fluids) including steam (w hich is a vapor) are limited or approach a maximum in mass flow velocity or rate, i.e., Ibs/sec or Ibs/hr through a pipe depending upon the specific upstream or starting pressure. This maximum rate of flow cannot be exceeded regardless of how much the dow nstream pressure is further reduced [3]. To determine the actual velocity in a pipe, calculate by... 

Figure 12-46H. Advanced datum impeller design reduces operating stresses and improves flow velocity. (Used by permission Dresser-Rand Company. All rights reserved.)...

Here w and d are width and depth and the units may be meters or millimeters. Alternatively, the diameter may be found from published charts. Using Figure 29.5 a pressure gradient (Pa/m) is chosen and with each change of volume flow a new diameter is found. This is converted to a convenient rectangular section equivalent to the round section. It will be seen that the velocity reduces. 

Continuous, surface blowdown arrangements employ a multistage nozzle valve that permits the BW to expand and flash gradually and safely across each successive orifice and chamber with almost no noise. This effect reduces the flow velocity and virtually eliminates the risk of wire drawing. The BD valve is provided with a regulating lever and calibrated dial (or an electric actuator) for either manual or automatic BD rate adjustment. Continuous blowdown arrangements are entirely suitable for incorporation into FSHR systems. They are commonly employed for WT boilers. 

Figure 8 shows that increasing the heat flux at constant mass velocity causes the peak in wall temperature to increase and to move towards lower enthalpy or steam quality values. The increase in peak temperature is thus due not only to a higher heat flux, which demands a higher temperature difference across the vapor film at the wall, but to a lower flow velocity in the tube as the peaks move into regions of reduced quality. The latter effect of lower flow velocity is probably the dominant factor in giving fast burn-out its characteristically rapid and often destructive temperature rise, for, as stated earlier, fast burn-out is usually observed at conditions of subcooled or low quality boiling. 

This system produces a steady laminar flow with a flat velocity profile at the burner exit for mean flow velocities up to 5m/s. Velocity fluctuations at the burner outlet are reduced to low levels as v /v< 0.01 on the central axis for free jet injection conditions. The burner is fed with a mixture of methane and air. Experiments-described in what follows are carried out at fixed equivalence ratios. Flow perturbations are produced by the loudspeaker driven by an amplifier, which is fed by a sinusoidal signal s)mthesizer. Velocity perturbations measured by laser doppler velocimetry (LDV) on the burner symmetry axis above the nozzle exit plane are also purely sinusoidal and their spectral... 

As will be outlined below, the computation of compressible flow is significantly more challenging than the corresponding problem for incompressible flow. In order to reduce the computational effort, within a CED model a fluid medium should be treated as incompressible whenever possible. A rule of thumb often found in the literature and used as a criterion for the incompressibility assumption to be valid is based on the Mach number of the flow. The Mach number is defined as the ratio of the local flow velocity and the speed of sound. The rule states that if the Mach number is below 0.3 in the whole flow domain, the flow may be treated as incompressible [84], In practice, this rule has to be supplemented by a few additional criteria [3], Especially for micro flows it is important to consider also the total pressure drop as a criterion for incompressibility. In a long micro channel the Mach number may be well below 0.3, but owing to the small hydraulic diameter of the channel a large pressure drop may be obtained. A pressure drop of a few atmospheres for a gas flow clearly indicates that compressibility effects should be taken into account. 

What is not commonly known outside the NMR community is the relative difficulty in making accurate relative density measurements by NMR/MRI compared, for example, with making velocity measurements by NMR/MRI. This is because density measurements rely on the signal strength, which can be affected by any number of factors. In contrast, the most common way to measure flow velocity by NMR/MRI is to use the phase of the NMR signal rather than the amplitude, which vastly reduces its sensitivity to amplitude variations. 

The spacing in the end zones will often be increased to provide more flow area at the inlet and outlet nozzles. The velocity in these zones will then be lower and the heat transfer and pressure drop will be reduced slightly. The effect on pressure drop will be more marked than on heat transfer, and can be estimated by using the actual spacing in the end zone when calculating the cross-flow velocity in those zones. 

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