Industrial fans are designed to move large volumes of gases at low pressure differentials.
● Gas Transport by Centrifugal Fan Procedure
In Design Mode, the program calculates the number of parallel units by comparing the operating throughput with the maximum throughput. The operating throughput is equal to the volumetric flowrate of the input stream (under input stream conditions). In Rating Mode, the user specifies the number of units and the rated throughput of each unit and the program calculates the operating throughput and warns the user if its value exceeds the rated throughput.
Energy Balances
The power requirement is calculated using the following equations (Shultz, 1962):
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where:
● k is the ratio of specific heat of gas at constant pressure to specific heat of gas at constant volume (average value = 1.3),
● v1 is the specific volume of gas at intake conditions,
● T1 is the absolute temperature of gas at intake conditions, and
● T2 is the absolute temperature of gas at final delivery conditions.
The user always specifies the desired pressure change (which is equivalent to specifying the value of p2) and the above equations are used to calculate the power requirement and the outlet temperature (T2). If the calculated T2 exceeds the maximum exit temperature, the program calculates the required cooling duty to maintain an exit temperature equal to the maximum.
1. Shultz, J.M. (1962). “The Polytropic Analysis of Centrifugal Compressors”, J. Eng. Power, Trans. Am. Soc. Mech. Eng., pp. 69-82 (January 1962).
2. Peters, M.S. and K.D. Timmerhaus, (1991). Plant Design and Economics for Chemical Engineers, 4th edition, McGraw-Hill, pp. 523-525.
The interface of this operation has the following tabs:
● Oper. Cond’s, see Gas Transport by Centrifugal Fan: Oper. Conds Tab
● Labor, etc, see Operations Dialog: Labor etc. Tab
● Description, see Operations Dialog: Description Tab
● Batch Sheet, see Operations Dialog: Batch Sheet Tab
● Scheduling, see Operations Dialog: Scheduling Tab
