Circulating capacity

Pumping, Velocity Head, and Power. Mechanical mixers can be compared with pumps (1) because they produce circulating capacity and velocity head H. The analogy between a pump and mixer can be appreciated by comparing a pumping loop with a mixing tank (Fig. 2). Power input P to a pump is represented by... 

The circulating capacity of 3-blade square pitch propellers is theoretically of the magnitude given in Figure 5-9. The speed ranges indicated may be grouped as [2] ... 

Figure 5-9. Theoretical circulating capacity of single propeller mixers. By permission, Fluid Agitation Handbook, Chemineer, Inc.

A marine propeller can be considered as a caseless pump. In this case its volumetric circulating capacity QA is related to volumetric displacement per revolution VD by the equation... 

Mutually conflicting scale-up rules are given by equations 5.32, 5.33 and 5.34. Other possible ways of scaling up are a constant tip speed uT, and a constant ratio of circulating capacity to head Qa a, and a constant power per unit volume P /F. Since PA is proportional to NiD and V is proportional to D, the ratio PA/T is proportional to N3D%. 

The circulating capacity QA of a square pitch propeller has already been... 

Equation 5.43 shows that the circulation capacity of low speed square pitch propellers greatly exceeds that of high speed propellers for the same power consumption and Reynolds number [Holland and Chapman (1966)]. 

Other possible ways of scaling up are constant tip speed ut(tiNDa), and a constant ratio of circulating capacity to head Q/h. 

In addition to effective smoke control, sufficient circulation capacity is needed to ensnre a prompt evacuation of the station. Many concepts and computer models have been developed for emergency evacuation applications. Using the hydranlic flow concept, hand calculation of exiting time is also possible. 

Safety design Natural circulation capacity and RVACS, LOHS, LOFA analyses completed... 

Power numbers, pumping numbers, shear levels, and flow patterns characterize the various impellers described above. All the power applied to the mixing system produces circulating capacity, Q, and velocity head, H, given by... 

The core is cooled by natural circulation in the range from full power operation to residual heat removal. There is a long riser on the core outlet to enhance the natural circulation capacity. The height of the riser is about 6 m. Even in case of interruption of natural circulation in the primary circuit due to a LOCA the residual heat of the core can be transmitted by steam condensed at the uncovered tube surface of the primary heat exchanger. 

---