Computational Fluid Dynamics Analysis of Cooling Tower Inlets

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
H. C. R. Reuter ◽  
D. G. Kröger
Keyword(s):  
Cooling Tower ◽  
Flow Patterns ◽  
Full Scale ◽  
Loss Coefficient ◽  
Cooling Towers ◽  
Cfd Model ◽  
Shell Wall ◽  
Natural Draft ◽  
Flow Losses ◽  
Loss Coefficients

Cooling tower inlet losses are the flow losses or viscous dissipation of mechanical energy affected directly by the cooling tower inlet design, which according to the counterflow natural draft wet-cooling tower performance analysis example given in Kröger (Kröger, 2004, Air-Cooled Heat Exchangers and Cooling Towers: Thermal-Flow Performance Evaluation, Pennwell Corp., Tulsa, OK), can be more than 20% of the total cooling tower flow losses. Flow separation at the lower edge of the shell results in a vena contracta with a distorted inlet velocity distribution that causes a reduction in effective fill or heat exchanger flow area. In this paper, a two-dimensional (axi-symmetric) computational fluid dynamic (CFD) model is developed using the commercial CFD code ANSYS FLUENT, to simulate the flow patterns, loss coefficients and effective flow diameter of circular natural draft cooling tower inlets under windless conditions. The CFD results are compared with axial velocity profile data, tower inlet loss coefficients and effective diameters determined experimentally by Terblanche (Terblanche, 1993, “Inlaatverliese by Koeltorings,” M. Sc. Eng. thesis, Stellenbosch University, Stellenbosch, South Africa) on a cylindrical scale sector model as well as applicable empirical relations found in Kröger, determined using the same experimental apparatus as Terblanche. The validated CFD model is used to investigate the effects of Reynolds number, shell-wall thickness, shell wall inclination angle, fill loss coefficient, fill type, inlet diameter to inlet height ratio and inlet geometry on the flow patterns, inlet loss coefficient and effective diameter of full-scale cooling towers. Ultimately, simple correlations are proposed for determining the cooling tower inlet loss coefficient and inlet effective flow diameter ratio of full-scale cooling towers excluding the effect of rain zones and the structural supports around the cooling tower entrance.

Inlet Losses in Counterflow Wet-Cooling Towers

2001 ◽  
Vol 123 (2) ◽  
pp. 460-464 ◽  
Author(s):  
E. de Villiers ◽  
D. G. Kro¨ger
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Numerical Model ◽  
Loss Coefficient ◽  
Cooling Towers ◽  
Empirical Correlations ◽  
Dependent Variables ◽  
Loss Coefficients

The inlet loss coefficients for dry, isotropically packed, circular and rectangular counterflow cooling towers are determined experimentally and empirical correlations are formulated to fit this data. Computational fluid dynamics is used to investigate the dependence of the inlet loss coefficient on the rain zone characteristics. The rain zone generally dampens the inlet loss, but the coupling is indirect and involves a large number of dependent variables. The numerical model is validated by means of experimental data for dry towers and it is found that the degree of accuracy achieved for circular towers exceeds that for rectangular towers. Consequently, the correlation derived to predict this occurrence for circular towers can be applied more confidently than its rectangular counterpart.

scholarly journals A CFD MODEL BASED ON WET DEPOSITION OF LARGE-SCALE NATURAL DRAFT COOLING TOWER

2019 ◽  
Vol 35 (esp01) ◽  
pp. 23-32
Author(s):  
Xuan Wang ◽  
◽  
Wenjie Bao ◽  
Xiaodong Huang ◽  
Xue Wang ◽  
...  
Keyword(s):  
Wet Deposition ◽  
Large Scale ◽  
Cooling Tower ◽  
Cfd Model ◽  
Natural Draft ◽  
Model Based

Flow Losses in Abrupt Enlargements and Contractions

1966 ◽  
Vol 88 (1) ◽  
pp. 73-81 ◽  
Author(s):  
R. P. Benedict ◽  
N. A. Carlucci ◽  
S. D. Swetz
Keyword(s):  
Compressible Flow ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Constant Density ◽  
Flow Losses ◽  
Loss Parameter ◽  
Loss Coefficients

In this paper, we examine losses associated with compressible and constant-density fluids flowing across abrupt area changes in flow passages. The bases of the conventional constant-density loss coefficients for abrupt enlargements and contractions are first reviewed. A loss parameter based directly on the drop in total pressure is next introduced. Various compressible-flow solutions are then considered. Results are given of new experiments run with air and water flowing across abrupt area changes. The total-pressure-loss parameter is shown to have greater utility and validity than the usual loss coefficient for both compressible and constant-density flows.

Study of Heat Rejection in Triple Natural Draft Dry Cooling Towers under Crosswind Using Radiator-Type Windbreakers

2014 ◽  
Vol 598 ◽  
pp. 265-270 ◽  
Author(s):  
Amir Hozhabr ◽  
Ramin Radi ◽  
Hossein Chenari ◽  
Arash Chogani ◽  
Masoud Esmaeelipour
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cooling Tower ◽  
Independent Solution ◽  
Numerical Results ◽  
Cooling Towers ◽  
Cooling Efficiency ◽  
Natural Draft ◽  
Computational Fluid Dynamics Cfd ◽  
Dry Cooling

In this paper, the effect of crosswind on triple natural draft dry cooling towers is studied and analyzed. Concerning this area, many researches have concentrated on one cooling tower. This research focuses on the mutual effects of the adjacent towers' performance, and also makes a comparison between the efficiency of the three cooling towers in windy and no-wind conditions, using Computational Fluid Dynamics (CFD). In modeling the crosswind condition, at first solid windbreakers, and then radiator-type windbreakers are used for each cooling tower. Finally, the water outlet temperatures of the radiators' cooling towers are analyzed, and the total heat rejections at different conditions are compared. Numerical results show that radiator-type windbreakers can substantially improve cooling efficiency more than usual solid-types. It should be mentioned that a complete grid study is done to achieve a grid-independent solution.

A New Two-Dimensional CFD Model to Predict the Performance of Natural Draught Wet-Cooling Towers Packed With Trickle or Splash Fills

2010 ◽  
Author(s):  
Hanno C. R. Reuter ◽  
Detlev G. Kro¨ger
Keyword(s):  
Cooling Tower ◽  
Air Flow ◽  
Linear Interpolation ◽  
Atmospheric Temperature ◽  
Performance Characteristics ◽  
Cooling Towers ◽  
Cfd Model ◽  
Flow Angle ◽  
Cfd Models ◽  
Air Inlet

In the design of a modern natural draught wet-cooling tower, structural and performance characteristics must be considered. Air flow distortions and resistances must be minimised to achieve optimal cooling which requires that the cooling towers must be modelled two-dimensionally and ultimately three-dimensionally to be optimized. It is found that CFD models in literature are limited to counterflow cooling towers packed with film fills which are porous in one direction only and generally have a high pressure drop, as well as purely crossflow cooling towers packed with splash fill, which simplifies the analysis considerably. Many counterflow cooling towers are however packed with trickle and splash fills which have anisotropic flow resistances, which means the fills are porous in all flow directions and thus air flow can be oblique through the fill, particularly near the cooling tower air inlet. This provides a challenge since available fill test facilities and subsequently fill performance characteristics are limited to purely counter- and crossflow configuration. This paper presents a CFD model to predict the performance of natural draught wet-cooling tower with any type of fill configuration, which can be used to investigate the effects of different atmospheric temperature distributions, air inlet and outlet geometries, air inlet heights, variations in radial water loading and fill depth, fill configurations, rain zone drop size distributions, and spray zone performance characteristics on cooling tower performance for optimization purposes. Furthermore the effects of damage or removal of fill in annular sections and boiler flue gas discharge in the centre of the tower can be investigated. The fill performance characteristics for oblique air flow are determined by linear interpolation between counter- and crossflow fill characteristics in terms of the air flow angle. The CFD results are validated by means of corresponding one-dimensional computational model data.

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