Mixing Impeller Power Number
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- Mixing Impeller Power Number
Note that as the impeller gets larger, the power number decreases drastically. The only perquisite to this strategy is that the torque must be carefully measured and it is important to measure the net impeller torque without bearing resistance. ... impeller power number (N p), shear stress τ, and mixing time t m. Sometimes …
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Thus, it is required to determine the mixing power and pumping capacity. For the tested configurations, the dependence of the mixing power number on the Reynolds number Eu = f(Re) will be determined, and then the dependence of the power number on the pitch of the impeller blade Eu = f(p/D). The second parameter …
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The correlation between impeller power consumption and fluid viscosity are well studied based on dimensionless analysis - Power number (N p) and Reynolds number (Re).But a generalized form to account for both Newtonian and …
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The power input P to an impeller of diameter D driven at a rotational speed N in a fluid of density ρ and viscosity η can be expressed in terms of a dimensionless Power number, P/(N 3 D 5 ρ). This is a form …
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Current literature relies almost exclusively on the power number to compare and characterize impellers. Industrial mixing requirements may rely on …
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Power numbers of many types of impellers can be found on the Impeller Page. Power Number of the Impellers in Standard Tank Geometries: To see just how good the CFD could predict the power numbers, we examined Case R (Fig. 6). ... The individual power numbers of Model LTR are lower than our verification in a "standard" mixing tank. This …
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Different approaches for the design of systems are suggested by Vogel 27, which are based on, e.g., mixing time, impeller tip speed or specific power input. ... Re is employed since the relationship between these two numbers normalizes the power input to the characteristics of an impeller 29. The power number is defined as (2) where P ...
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The value of the dimensionless power number (Np) depends on several factors including impeller design, number of impellers and location within a tank, tank baffling and fluid viscosity. Typically the …
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Figure 9. Variation of power number with Reynolds number for threediameters of down-pumping four bladed 45¯ pitched blade impellers(Tˆ240mm, CˆT=3). Trans IChemE, Vol 80, Part A, May 2002 EFFECT OF IMPELLER AND TANK GEOMETRY ON POWER NUMBER 369 reducing the mass bullet6 owrate in the …
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Design and operation of mixing systems using agitated vessels is a difficult task due to the challenge of obtaining accurate information on impeller-induced turbulence. The use of Computational Fluid Dynamics (CFD) can provide detailed understanding of such systems. In this study, experimental tests and computational fluid dynamics simulations were …
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The power number of each impeller was determined through direct measurement of the required power, P, to drive the impeller. ... Interrelations among mixing time, power number, and discharge flow rate number in baffled mixing vessels. J. Chem. Eng. Jpn., 18 (1985), pp. 47-52. Crossref View in Scopus Google Scholar
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Turbulent power for a batch rotor–stator device can be described by a single "tank" type impeller power number, Po, Eq. (1) ( Atiemo-Obeng and Calabrese, 2004, Calabrese and Padron, 2008, Doucet et al., 2005 ), where D is the impeller diameter, N is the rotor speed, ρ is the liquid density, and P is the shaft power for the impeller.
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The new correlation equations of power number, based on the correlation of Kamei and Hiraoka, were developed for several kinds of mixing impellers, and it was …
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The power number correlations for two-stage referred to Design Handbook for Practical Subject of Chemical Engineering (PartII) (Wang et al., 2002). In this investigation, the power number for double-stage 4-PBT was twice the power number of single impeller. 1.3 Numerical method Computational grids The grids of tank domain and impeller …
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The Reynolds number allows to calculate a viscosity power factor by using the graph below : Graph 1 : fμ as a function of N Re = D 2.N.ρ/μ. The actual turbulent power number can then be calculated with : Np actual = fμ * Np. With : N = actual turbulent power number (-) fμ = viscosity power factor (-) - see graph above Np = power ...
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Power number, abbreviated as (N_p), a dimensionless number, represents the proportional drag force and inertial force.It is used in momentum transfer and power consumption by fans, mixers and pump impellers at a specified rotational speed. The power number formula depends on the geometry of the impeller, the Reynolds …
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Comparison of Power Number of Propeller Impeller with Rushton's Data. Figure 10 shows the comparison of power number of a propeller impeller by Rushton et al. ... As mentioned above, the correlation reproduced in this work has a possibility of correlating the power number of the mixing impellers of all geometry. It is the first time …
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The most common of mixing impellers. PF3 Hydrofoil Impeller provides excellent pumping ability with a strong axial flow. While useful in most applications, this design excels in thinner fluids that are susceptible to settling and provides the MOST pumping per unit of torque input. ... POWER NUMBER (NP) = 0.3; FLOW NUMBER (NQ) = 0.5; Flow ...
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2.1.. Power number measurementsThe power consumption in an impeller agitated vessel was calculated using the load (w g) measured by the load cell setup associated with the torque table with the controlled traversing mechanism [16].The position of the shaft was fixed while the impeller off-bottom clearance could be altered by …
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P = Rotor power consumed in Watt N p = Power Number ρ = Density of liquid, kg/m 3 n 3 = Rotor / agitator speed measured in revolutions / second D 5 = Rotor / impeller diameter in meter's. Remember: That Power Number decreases with an increase in Reynolds number. Read articles to be downloaded on page - "Power Number definition".
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All power numbers reported within this course will deal with correlation results in the turbulent flow regime and be reported as a constant. Power number constants are listed in Table 2 for the various impeller types shown in Figure 3. Figure 5 and Table 1 are references for the various shape parameters that impact the power number.
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Fig. 10 shows the power number of the three different impellers at various Reynolds numbers. In general, the power number tends to be a constant when the Reynolds number Re > 10 4. As shown in Fig. 10, the power numbers of three impeller mixing systems were relatively stable. The power number of self-similarity 1 impeller …
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variables is usually expressed in terms of dimensionless numbers such as the impeller Reynolds number (Re) i and the power number N p. N p is defined as: and N p = 3 5 N i D i P ρ (6.5) P = N ...
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Leveraging computational fluid dynamics simulations, we have identified a power number of 15,000–40,000 to maximize the catalyst effectiveness factor and …
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is the impeller's power number and it is a drag coef- ficient that is determined by the geometry of the impeller (blade width, blade angle, number of blades and so on.).
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Taghavi et al. (2011), who investigated mixing power consumption in STBR in single- and two-phase conditions, ... fluid density (ρ) and the impeller power number (P 0). Power consumption is defined by the power correlation of the …
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A large plate impeller was rotated back and forth in a cylindrical vessel. Simultaneous and continuous measurements of the rotational torque on the mixing shaft and impeller angular position were ...
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The time of mixing (t) Power requirement (P) Impeller size (d) Tank size (D) Stirrer speed (n) rev/s (s 1) needed to achieve any required degree of uniformity of the mixture. The charts and ... Re Impeller Reynolds number, dimensionless P Mixing power, W t Time, s m Viscosity, kg/m s r Density, kg/m3 Problems 1. Consider Example 1.
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P = shaft power required (W) Np = power number (-) D = impeller diameter (m) N = agitator speed (r/s) ρ = liquid density (kg/m3) If the power number of an agitator is known, it is then possible to calculate the shaft power as : P = Np.ρ.N 3.D 5. Now the question is to find out what is the power number for a particular agitator.
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Power number is the ratio of net power to theoretical power (NP=Pnet/ρN3D5), where ρ is the effective fluid density, N is impeller speed (rps), and D is the diameter of the …
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Significance of Power Number. Agitation Intensity and Flow Patterns: The power number helps determine the intensity of agitation within the mixing vessel. A high power number implies intense mixing with vigorous flow patterns, while a low power number suggests a more gentle and less turbulent mixing process.
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is the impeller's power number and it is a drag coef-ficient that is determined by the geometry of the impeller (blade width, blade angle, number of blades and so on.). The primary flow generated by an impeller is calculated from Equation (2): Q = Fl N D. 3 (2) Fl. is the impeller's flow, or pumping number. Both the power and flow numbers ...
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