Efficiency ratio, pump

Ev = volumetric efficiency, ratio of actual pump capacity to the volume displaced/imit time... 

Volumetric efficiency, ratio of actual pump capacity to volume displaced per unit of time Pump efficiency with water, percent Pump efficiency with viscous fluid, percent Pump efficiency, fraction Pump efficiency with water, fraction Pump efficiency with viscous fluid, fraction Volumetric efficiency, fraction Maximum safe flowng efficiency, overall pump, fraction... 

As stated, a medium mechanical pump can only have speeds of 11.7-25 liters/ sec. However, a comparable-sized diffusion pump can achieve speeds of up to 30 liters/sec, but with 2-3 times the vacuum capacity. It is easy to see why the assistance of an auxiliary pump is required to effectively obtain vacuums beyond 10 4 torr, such as those in the high or even ultrahigh-vacuum range. Although it is possible to obtain larger and faster mechanical pumps, the cost/efficiency ratio starts to go down and it becomes less expensive to use a mechanical/diffusion pump combination. For more information on pumping speeds, see page 347. 

Brake efficiency—Ratio of the power given to the fluid to the brake input power (brake power) to the pump. 

Fig. 3 Cavity arrangement in the upper rotor and lower stator disks of a CDDM in rotor-stator disk configuration. Elongated cavities are more efficient in pumping/conveying and smaller-aspect ratio cavities are for mixing. (A) Upper rotor. (B) Lower stator. (From Ref l) (View this art in color at www.dekker.com.)...

Seasonal Energy Efficiency Ratio (SEER) - A measure of seasonal or annual efficiency of a central air conditioner or air conditioning heat pump. It takes into account the variations in temperature that can occur within a season and is the average number of Btu of cooling delivered for every watt-hour of electricity used by the heat pump over a cooling season. 

The assessment for pumps/compressors and steam turbines together can be done by first estimating the process power requirement for running pumps or compressors based on equations (8.1) and (8.2). Then the current steam rate can be measmed online and specific steam rate is estimated from the theoretical steam table. The ratio of process power requirement and the theoretical power delivered from the steam turbine indicates the overall efficiency of pump/compressors and turbines combined. If the efficiency is much lower than design, extra steam must be required to run the same pump or compressor. 

Concepts of Head Ratio and Efficiency Ratio When Pumping Solids... 

It is important to appreciate the work of Hunt and Faddick. Often, a pump vendor will produce a chart or curve to obtain the head and efficiency ratio. The limitations of such curves are that they apply only to pumps of similar geometrical design. The discrepancy of 5-10% between one design and another may have to be absorbed by the motor. 

To determine the effect of particle size on the pump performance perlite-A, perlite-B and perlite-C samples were chosen. To analyse the pump performance test results, the relative reduction in head developed and the efficiency of the pump for different concentrations of three perlites were computed in terms of the head ratio (Hr) and the efficiency ratio (r r) at various flow rates respectively. These ratios have been defined as follows ... 

To study the effect of particle size on pump performance, the average value of Hr and Tjr at any given concentration were calculated from the head ratio-flow rate and the efficiency ratio-flow rate characteristic curves. It has been observed that r r is almost equivalent to the corresponding Hr for a given operating condition of the pump. The variation of the average value of Hr with various concentrations of perlite-A, perlite-B and perlite-C slurries has been compared in Fig. 3. It is seen that, both Hr and Tjr decrease linearly with the increase in the concentration of the solids. For any concentration of the solids, both Hr and r r decrease with the increase in particle size of the perlite. This could be attributed to the reason that the energy required to maintain the solid in suspension and motion increases with the increase in the particle size. 

In order to investigate tip clearance effects on the pump performance, the values of Hr and r r at any given concentration were obtained from the head ratio-flow rate and the efficiency ratio-flow rate characteristic curves plotted for various tip clearances (x=1.25 mm, x=5.5 mm and x=8 mm) taking the best efficiency point as basis, [4]. The variation of the value of Hr and Pr with various relative tip clearances for two concentrations of perlite-A slurry is illustrated in Fig. 5. The value of Hr and r r for a=0 % was obtained from the closed impeller tests. In Fig. 5, the results show that, at first Hr and pr increase up to 5 % relative tip clearance, after that, tend to decrease until 22 % is reached... 

The determination of equations (11) and (16) along with the determination of Figure 3 forms the basis for Figure 4 which is the end result of the analysis. Here the effect of the jet pump on efficiency ratio and suction specific speed ratio is shown. The effect of the specification parameter, P, is shown and the curves are related to Figure 3 by including lines of constant values of rj. The data from Figures 3 and 4 are used in the following manner ... 

The flow ratio through the centrifugal pump is shown in Figure 6 as a function of the overall efficiency ratio of the system. It can be seen that at extremely low values of NPSH, the gross flow through the centrifugal pump is increased appreciably. 

The above analysis assumes that there is no increase in vapor pressure in the recirculated flow due to the heat addition in the pump. At very low values of inlet NPSH it is necessary that this factor be considered. Inasmuch as this heat addition depends on the efficiency ratio, an iteration process is necessary. 

Figure 6. Efficiency ratio vs jet pump flow ratio for small values of jet pump head ratio...

From the relationship of the flow ratio to the efficiency ratio, it is established that the flow ratio for this efficiency ratio is 5.3 indicating that an increase of less than 20 per cent in flow through the mainstage is required to achieve the operation of this system with the vented tank. This particular example shows the importance of the concept of the jet pump-centrifugal pump combination when specifications of the type herein considered are encountered. 

The theoretical delivery of a piston pump is equal to the total swept volume of the cylinders. The actual delivery may be less than the theoretical value because of leakage past the piston and the valves or because of inertia of the valves. In some cases, however, the actual discharge is greater than theoretical value because the momentum of the liquid in the delivery line and sluggishness in the operation of the delivery valve may result in continued delivery during a portion of the suction stroke. The volumetric efficiency, which is defined as the ratio of the actual discharge to the swept volume, is normally greater than 90 per cent. 

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