This paper develops the effectiveness-NTU design method for cooling towers. The definitions for effectiveness and NTU are totally consistent with the fundamental definitions used in heat exchanger design. Sample calculations are presented for counter and crossflow cooling towers. Using the proper definitions, a person competent in heat exchanger design can easily use the same basic method to design a cooling tower of counter, cross, or parallel flow configuration. The problems associated with the curvature of the saturated air enthalpy line are also treated. A “one-increment” design ignores the effect of this curvature. Increased precision can be obtained by dividing the cooling range into two or more increments. The standard effectiveness-NTU method is then used for each of the increments. Calculations are presented to define the error associated with different numbers of increments. This defines the number of increments required to attain a desired degree of precision. The authors also summarize the LMED method introduced by Berman, and show that this is totally consistent with the effectiveness-NTU method. Hence, using proper and consistent terms, heat exchanger designers are shown how to use either the standard LMED or effectiveness-NTU design methods to design cooling towers.
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Design of Cooling Towers by the Effectiveness-NTU Method
H. Jaber,
H. Jaber
Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA 16802
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R. L. Webb
R. L. Webb
Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA 16802
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H. Jaber
Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA 16802
R. L. Webb
Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA 16802
J. Heat Transfer. Nov 1989, 111(4): 837-843 (7 pages)
Published Online: November 1, 1989
Article history
Received:
April 6, 1988
Revised:
November 15, 1988
Online:
October 20, 2009
Citation
Jaber, H., and Webb, R. L. (November 1, 1989). "Design of Cooling Towers by the Effectiveness-NTU Method." ASME. J. Heat Transfer. November 1989; 111(4): 837–843. https://doi.org/10.1115/1.3250794
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