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Title:	Power characteristics of disc type agitator impellers
Author:	Rubin, Isadore
View Online:	njit-etd1955-025 (vii, i117 pages ~ 7.7 MB pdf)
Department:	Department of Chemical Engineering
Degree:	Master of Science
Program:	Chemical Engineering
Document Type:	Thesis
Advisory Committee:	Salamone, Jerome J. (Committee chair)
Date:	1955-06
Keywords:	Mixing machinery
Availability:	Unrestricted
Abstract:	Experiments were conducted to determine the power required to drive disc type agitators and to observe the flowpattern and type of agitation produced in a baffled tank. Power was measured by determining electrical energy input to a motor and subtracting motor transmission and friction losses previously established by calibration. Impellers were operated at speeds from 600 to 3700 RPM. Power requirements in the turbulent flow region were correlated by the equation HP = PoL5N3ρ/550gc which was derived theoretically. Reports of previous work on agitator power are discussed. The Power Numbers (Po) established for the turbulent range, were all less than one. This is considerably lower than the Power Number for most common commercial Impellers in baffled tanks, other than propellers. This means that at corresponding Reynolds numbers, discs absorb less power than paddles or turbines. Effective agitation throughout the entire vessel was only obtained at peripheral speeds substantially above the 700 ft. per min. recommended in the literature. Some of the impellers used went through a narrow critical speed range which caused vibration. Above and below this range there were no operating difficulties. These impellers should be adaptable and useful for industrial applications and may be directly connected to a standard motor without a speed reducer.