Bore fluid flow rates

Feng et al. [32] studied the morphology of the inner and outer surfaces of hollow fibers fabricated from poly(etherimide) by TM-AFM. The hollow fibers were fabricated by the dry-wet phase inversion method at two different bore fluid flow rates, 0.1 and 0.4 mLmin and their effect on the surface morphology was investigated. The average pore sizes on the inner surface were 39.8 and 81.9 nm, respectively, for 0.1 and 0.4 mLmin while those on the outer surface were 218.4 and 93.4, respectively, for 0.1 and 0.4 mLmin h It is interesting to note that the pore size increased with an increase in the bore fluid flow rate at the inner surface, while the opposite was the case at the outer surface. 

For unsupported polymeric membranes (i.e. hollow fibers), spinning parameters are cracial factors that must be controlled during hollow fiber preparation. These parameters include the amount and types of polymer, solvents, and additives mixed irrto the spimung dope, the dope and bore fluid flow rates, the fibre take-up velocity, the air gap distance (unless wet spinning is used), and the coagulant bath temperature [31,71]. The main challenges in hollow fiber spinning, as proposed by Puri [72], are ... 

The PAN polymer solution and the bore fluid are extmded simultaneously from a spiimeret (dimension OD ID = 600 300 pm) to form a nascent hollow fiber membrane at ambient temperature. The ratio of polymer solution and bore fluid flow rate is 3 to 1. A gear pump is used to deliver the polymer solution to the spinneret smoothly at a certain dope extrasion rate (DER) ranging from 1.5 to 3.0 cm /min. The fiber is then directed to a chamber with a forced flow of nitrogen for dry phase... 

For Crooks Gap, the amount of calcite that actually dissolved was estimated using the excess calcium concentrations, the percentage of water in total fluid produced, and fluid flow rates. The total volume of calcite dissolved was approximately 2.8 x 10" m (1.0 ft ). Although this seems a small amount, if it had all reprecipitated downhole as scale in the well bore, it could cause serious damage for a submersible pump with tolerances measured in micrometres. 

The relationship between the bore fluid pressure drop, AP and its flow rate is defined by Poiseuike s law ... 

When a fluid is flowing through a pipe, resistance to flow is caused by friction. The pipe bore selected for each section must be such that under any operating conditions, the initial head, either static head of oil in the supply tank or the pump delivery pressure, will be adequate to ensure the required flow rate. Additionally, any change of flow rate and consequent variation in loss of head must not adversely affect the operation of the associated oil-burning equipment. 

Fig. 2.6.10 Specialized experimental set-up for microfluidic flow dispersion measurements. Fluid is supplied from the top, flows via a capillary through the microfluidic device to be profiled and exits at the bottom. The whole apparatus is inserted into the bore of a superconducting magnet. Spatial information is encoded by MRI techniques, using rf and imaging gradient coils that surround the microfluidic device. They are symbolized by the hollow cylinder in the figure. After the fluid has exited the device, it is led through a capillary to a microcoil, which is used to read the encoded information in a time-resolved manner. The flow rate is controlled by a laboratory-built flow controller at the outlet [59, 60].

Once the well is drilled, the oil is either released under natural pressure or pumped out. Normally crude oil is under pressure (were it not trapped by impermeable rock it would have continued to migrate upward), because of the pressure differential caused by its buoyancy. When a well bore is drilled into a pressured accumulation of oil, the oil expands into the low-pressure sink created by the well bore in communication with the earth s surface. As the well fills up with fluid, a back pressure is exerted on the reservoir, and the flow of additional fluid into the well bore would soon stop, were no other conditions involved. Most crude oils, however, contain a significant amount of natural gas in solution, and this gas is kept in solution by the high pressure in the reservoir. The gas comes out of solution when the low pressure in the well bore is encountered and the gas, once liberated, immediately begins to expand. This expansion, together with the dilution of the column of oil by the less dense gas, results in the propulsion of oil up to the earth s surface As fluid withdrawal continues from the reservoir, the pressure within the reservoir gradually decreases, and the amount of gas in solution decreases. As a result, the flow rate of fluid into the well bore decreases, and less gas is liberated. The fluid may not reach the surface, so that a pump (artificial lift) must... 

It has been demonstrated that radial dispersion contributes more significantly to the dilution of the sample in the flow than does axial dispersion. This type of fluid movement, termed secondary flow by Tijssen [43], results in a washout effect accounting for the low mutual contamination of samples successively injected into a carrier stream. TTiis advantageous feature is a result of the use of low flow rates and small tubing bores, and results in decreased peak-width and hence to increased sampling rate. 

A variety of fluid administration sets are available commercially. Sets that include large-bore tubing and a coil are suitable for most situations in adult horses and are recommended. Coils can also be helpful in neonatal foals, but wide-bore tubing is unnecessary. The flow rate can be estimated by counting the number of drops per 10 s in the drip chamber (Table 17.17) or can be set by using an electronic infusion pump. In all situations, a record should be kept of the time the infusion was started and the infusion rate to ensure that the desired volume is being delivered in the appropriate time. 

A few types of flowmeters measure the mass flow rate directly, but the majority measure the volumetric flow rate or the average fluid velocity, from which the volumetric flow rate can be calculated. To convert the volumetric rate to the mass flow rate requires that the fluid density under the operating conditions be known. Most meters operate on all the fluid in the pipe or channel and are known as full-bore meters. Others, called insertion meters, measure the flow rate, or more commonly the fluid velocity, at one point only. The total flow rate, however, can often be inferred with considerable accuracy from this single-point measurement. 

Pressure taps are required on each side of the orifice plate to allow the measurement of the pressure drop across the plate when the fluid is flowing. Knowing the differential pressure, the ratio of the orifice plate bore to pipe inside diameter (beta ratio) and fluid density, the flow rate can be calculated. 

There are many methods by which well-bore fluids can be raised to the platform or land level. In situations where high flow rates are required, the main options are -... 

These rheometers are widely used to study the rheological behavior of molten polymers. As shown in Figure 3.35 the fluid is forced from a reservoir into and through a fine-bore tube, or capillary, by either mechanical or pneumatic means. The fluid is maintained at isothermal conditions by electrical temperature control methods. Either the extrusion pressure or volumetric flow rate can be controlled as the independent variable with the other being the measured dependent variable. 

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