Computational Models for Predicting Cooling Tower Fill Performance in Cross-Counterflow Configuration

2010 ◽  
Author(s):  
Hanno C. R. Reuter ◽  
Detlev G. Kro¨ger
Keyword(s):  
Computational Models ◽  
Cooling Tower ◽  
Air Flow ◽  
Three Dimensional ◽  
Cooling Water ◽  
Transfer Characteristic ◽  
Linear Interpolation ◽  
Water Evaporation ◽  
Cooling Towers ◽  
Flow Angle

In cooling towers packed with trickle or splash fills, which have almost isotropic or anisotropic flow resistance, the air flow through the fill is oblique or in cross-counterflow to the water flow, particularly at the cooling tower inlet when the fill loss coefficient is small or when the fill hangs down into the air inlet region. This results that the fill Merkel number or transfer characteristic for cross-counter flow is between that of purely counter- and crossflow fills. When using CFD to model natural draught wet-cooling tower performance for isotropic fill resistance, two- or three-dimensional models are therefore required to determine fill performance. In this paper, the governing fundamental partial differential equations are derived in cylindrical and Cartesian co-ordinates to determine the cooling water temperature, water evaporation rate, air temperature and air humidity ratio in two-dimensional cross-counterflow fills for both saturated and supersaturated air. To solve these equations, a relation is proposed to determine Merkel numbers for oblique air flows by linear interpolation and extrapolation of purely cross- and counterflow Merkel numbers in terms of the air flow angle. This model is compared to analytical Merkel numbers obtained for different air flow angles using a single drop trajectory model. A linear upwind computational model and an Eulerian FLUENT® model are developed to evaluate fill performance characteristics from test data and to model fill performance in cooling towers respectively. The results of these two models are compared and verified with a FLUENT® Euler-Lagrange model.

Computational Models for Predicting Cooling Tower Fill Performance in Cross-Counterflow Configuration

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
H. C. R. Reuter ◽  
D. G. Kröger
Keyword(s):  
Computational Models ◽  
Cooling Tower ◽  
Air Flow ◽  
Three Dimensional ◽  
Cooling Water ◽  
Transfer Characteristic ◽  
Linear Interpolation ◽  
Water Evaporation ◽  
Cooling Towers ◽  
Flow Angle

In cooling towers packed with trickle or splash fills, which have anisotropic flow resistance, the air flow through the fill is oblique or in cross-counterflow to the water flow, particularly at the cooling tower inlet when the fill loss coefficient is small or when the fill hangs down into the air inlet region. This results in that the fill Merkel number or transfer characteristic for cross-counter flow is between that of purely counter- and crossflow fills. When using CFD to model natural draught wet-cooling tower performance for isotropic fill resistance, two- or three-dimensional models are therefore required to determine fill performance. In this paper, the governing fundamental partial differential equations are derived in cylindrical and Cartesian coordinates to determine the cooling water temperature, water evaporation rate, air temperature, and air humidity ratio in two-dimensional cross-counterflow fills for both saturated and supersaturated air. To solve these equations, a relation is proposed to determine Merkel numbers for oblique air flows by linear interpolation and extrapolation of purely cross- and counterflow Merkel numbers in terms of the air flow angle. This model is compared to analytical Merkel numbers obtained for different air flow angles using a single drop trajectory model. A linear upwind computational model and an Eulerian FLUENT® model are developed to evaluate fill performance characteristics from test data and to model fill performance in cooling towers, respectively. The results of these two models are compared and verified with a FLUENT Euler–Lagrange model, showing minor deviations.

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.

scholarly journals Corrosion processes in cooling towers

2013 ◽  
Vol 12 (3) ◽  
pp. 231-238
Author(s):  
Teresa Szymura ◽  
Wojciech Adamczyk
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Structural Steel ◽  
Ammonium Sulfate ◽  
Ammonium Chloride ◽  
Cooling Tower ◽  
Cooling Water ◽  
Corrosion Testing ◽  
Electrochemical Methods ◽  
Cooling Towers

Corrosion testing was performed on structural steel of a cooling tower in the environment of cooling water containing ammonium sulfates and ammonium chloride. The test were performed using gravimetric and electrochemical methods with the application of a potentiostat. The analyses clearly showed that the corrosion rate is higher in solutions that contain ammonium sulfate and that the S235JRG2 steel exhibits higher corrosion resistance in this environment.

Application of Artificial Neural Network for Modeling of Mechanical Cooling Tower

2011 ◽  
Vol 383-390 ◽  
pp. 7746-7749 ◽  
Author(s):  
Wei Shun Huang ◽  
Ching Wei Chen ◽  
Cheng Wen Lee ◽  
Ching Liang Chen ◽  
Tien Shuen Jan ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Water Flow ◽  
Cooling Tower ◽  
Air Flow ◽  
Cooling Water ◽  
Computation Method ◽  
Cooling Load ◽  
Artificial Neural ◽  
Tower Model

The objective of the study is to focus on the application of the artificial neural network to configure a heat-radiating model for cooling towers within the parameters of fluctuating in air flow or cooling water flow. To achieve the objective, a cooling tower heat balancing equation have been used to instill the correlations between a cooling tower cooling load to the four predefined parameters. Based on the premise established, the parameters of a cooling tower’s air flow and cooling water flow in a modulated process are utilized in an experimental system for collecting relevant operating data. Lastly, the artificial neural network tool derived from the Matlab software is utilized to define the input parameters being – the cooling water temperature, ambient web-bulb temperature, cooling tower air flow, and cooling water flow, with an objective set to instilling a cooling tower model for defining a cooling tower cooling load. In addition, the tested figures are compared to the simulated figures for verifying the cooling tower model. By utilizing the method derived from the model, the mean error of between 0.72 and 2.13% is obtained, with R2 value rated at between 0.97 and 0.99. The experiment findings show a relatively high reliability that can be achieved for configuring a model by using the artificial neural network. With the support of an optimized computation method, the model can be applied as an optimization operating strategy for an air-conditioning system’s cooling water loop.

Three-Dimensional Numerical Calculations of Flow and Plume Spreading Past Cooling Towers

1987 ◽  
Vol 109 (1) ◽  
pp. 113-119 ◽  
Author(s):  
A. O. Demuren ◽  
W. Rodi
Keyword(s):  
Temperature Field ◽  
Computer Model ◽  
Cooling Tower ◽  
Three Dimensional ◽  
Computer Code ◽  
Quantitative Agreement ◽  
Cooling Towers ◽  
Rectangular Grid ◽  
Complex Flow ◽  
Densimetric Froude Number

The paper reports on the application of an existing three-dimensional computer code to the calculation of the flow and temperature field past cooling towers. The code uses a rectangular grid so that the round tower geometry has be approximated by steps. Simulations are presented of various idealized laboratory studies carried out with cylindrical cooling tower models with the ratio of plume exit to cross-wind velocity varying in the range 0.2 to 1.7 and the densimetric Froude number in the range ∞ to 2. By comparison with the experimental results it is shown that the computer model is capable of reproducing the main features of the complex flow and temperature field past cooling towers including the downwash effect at strong cross winds. The quantitative agreement is not always entirely satisfactory, and suggestions are made for improving the computer model.

A Review of Common Problems Observed in Cooling Water Intakes and the Use of Physical Models to Develop Effective Solutions

2015 ◽  
Author(s):  
David Werth ◽  
Matthew Havice
Keyword(s):  
Physical Model ◽  
Cooling Tower ◽  
Cooling Water ◽  
Water Systems ◽  
Water Levels ◽  
Cooling Towers ◽  
Flow Conditions ◽  
Design Features ◽  
Model Studies ◽  
Common Problems

Pump intake structures are a necessary component of the cooling water systems for power plants, process and manufacturing facilities, flood control and water/wastewater applications. Large cooling water systems often use substantial sea / river water intakes or cooling towers to provide the required cooling of the process or circulating water. These structures can be very large and often house multiple pump with capacities ranging in size from a few hundred m3/hr to 60,000 m3/hr or more. With such large flow rates care must be taken to ensure uniform flow to the pump to limit vortex activity, vibration, flow induced cavitation and performance problems. In many cases, a physical hydraulic model study is conducted to evaluate the overall approach flow and the performance of the intake. This paper presents a synopsis of several recent physical model studies and a review of recurring problems associated with common design features. This paper takes a closer look at stop log support walls, an intake design feature common to seawater intakes. This wall is often used to minimize the height of the stop logs. In applications with large variations of water level, such as a seawater intake, there are times when the support walls are submerged significantly, resulting in significant flow disturbances. A feature common to cooling towers is the use of 90-degree suction elbows to supply horizontal pumps. A review of short radius vs. long radius elbow performance is presented. Cooling towers often have another common feature which is a significant difference in depth between the cooling tower basin and the pump sump. This results in typical shallow basins and deeper sumps. A common problem is the utilization of minimum pump submergence to set the water levels without reference to the basin invert elevation. A discussion of choked flow conditions in cooling towers is presented. A final discussion is presented regarding cross-flow and the use of concentrated supply channels in cooling tower applications to facilitate the isolation of individual tower cells. This paper presents a synopsis of several recent physical model studies and a review of recurring problems associated with common intake design features. The results of several model studies are presented to demonstrate the negative impacts that these common intake features have on approach flow conditions. The intent of the paper is to provide the design engineer some additional guidance not offered in industry guidelines or standards with the hope of avoiding common problems which can be costly and difficult to remediate after the intake has been constructed.

Decreasing the Tendency of Water to Form Scale and Corrosion in Cooling Towers – South Refineries Company (SRC) – Iraq

2021 ◽  
Vol 11 (2) ◽  
pp. 15-29
Author(s):  
Thabit Abbas ◽  
Qays Muthna ◽  
Thikra Shihab ◽  
Ola Jabur
Keyword(s):  
Cooling Tower ◽  
Saturation Index ◽  
Cooling Water ◽  
Feed Water ◽  
Cooling Towers ◽  
Raw Water ◽  
Technical Problems ◽  
Pipeline Networks ◽  
Langelier Saturation Index ◽  
Plant Data

Scale formation and corrosion phenomena are major technical problems at Basra Refinery/ South Refineries Company (SRC). These technical problems are concentrated in cooling towers which are used to supply cooling water to the processing units. The Scales and corrosion products precipitate inside cooling units, heat exchangers and pipeline networks affecting negatively efficiency of refinery’s equipment. In this work, a real plant data was collected from four cooling towers which is supplied the coolant to the crude distillation units of the refinery and also from the raw water supplier. The collected data was fitted by Langelier model to predict the tendency of cooling water for scale forming and activation of corrosion. The obtained result shows that the cooling water has a tendency to form scale (CaCO3 Precipitation) at cooling tower units. Also the feed water has the same tendency for scale forming.After analyzing the LSI (Langelier Saturation Index) results, the research team recommends the particular company to overcome this problem by installing a Reverse Osmosis (RO) plant for treating raw water to decrease the concentrations of total dissolved solids (TDS) which result scale and corrosion in the parts of cooling tower as an option to solve the problem.

scholarly journals Modeling of a Spray Assisted Natural Draft Cooling Tower

2008 ◽  
Vol 31 (1) ◽  
pp. 118-126
Author(s):  
O.K. Kaunde
Keyword(s):  
Momentum Transfer ◽  
Cooling Tower ◽  
Current Flow ◽  
Cooling Water ◽  
Transfer Model ◽  
Cooling Towers ◽  
Air Flow Rate ◽  
Transfer Unit ◽  
Novel Design ◽  
Gas Ratio

Cooling towers are one of the largest heat and mass transfer devices that are in common use. A novel type of cooling tower has been proposed in which air flow rate into the tower is drawn by ejector action of sprays instead of fans as is done in conventional mechanical forced or induced draft cooling towers. This novel design offers the potential of savingthe energy cost for driving the fan. The paper presents mathematical models for momentum transfer which is the driving force causing the entrainment of air. Also the heat transfer model for co-current flow of liquid and gas in the tower has been presented. The liquid to gas ratio tend to decrease as liquid rate increases. The ratio attained in the experimentallaboratory tower was 3.3, correspondingly the Momentum transfer efficiency for the tower was 60% and was the highest. Experiments for cooling water initially at 45 o C to final water temperature 27 o C showed that the cooling tower efficiency was 54% and number of transfer unit 0.8.

Experimental Investigation on the Effect of Fill Materials in Cooling Towers

2015 ◽  
Vol 766-767 ◽  
pp. 505-510 ◽  
Author(s):  
J. Jayaprabakar
Keyword(s):  
Corrosion Resistance ◽  
High Efficiency ◽  
Cooling Tower ◽  
Water System ◽  
Cooling Water ◽  
Cross Flow ◽  
Water Source ◽  
Coefficient Of Performance ◽  
Advanced Materials ◽  
Cooling Towers

The cooling water system is the industry’s primary way of conserving water. Modern water cooling towers were invented during the industrial age to dissipate heat when natural cooling water sources were available. The origin of cooling towers made the plant site selection independent of the availability of water source. The development of new, high efficiency film fills produced from light weights, flame retarded PVC reduces the size and weight of cross flow cooling towers. Today’s cooling tower combine the latest advanced materials to achieve the optimum balancing of High corrosion resistance, product durability and cost. Based on their specific functions, cooling tower components are designed using the materials with the best combination of corrosion resistance and physical properties. In this work, the coefficient of performance is determined by using Simpson’s rule and the performance of cooling tower at various L/G ratios is evaluated. The optimum approach of the tower is calculated.

scholarly journals Decreasing the Tendency of Water to Form Scale and Corrosion in Cooling Towers – South Refineries Company (SRC) – Iraq

2021 ◽  
Vol 11 (2) ◽  
pp. 15-29
Author(s):  
Thabit Abbas ◽  
Qays M. Ammouri ◽  
Thikra Shihab ◽  
Ola Jabur
Keyword(s):  
Cooling Tower ◽  
Saturation Index ◽  
Cooling Water ◽  
Feed Water ◽  
Cooling Towers ◽  
Raw Water ◽  
Technical Problems ◽  
Pipeline Networks ◽  
Langelier Saturation Index ◽  
Plant Data

Scale formation and corrosion phenomena are major technical problems at Basra Refinery/ South Refineries Company (SRC). These technical problems are concentrated in cooling towers which are used to supply cooling water to the processing units. The Scales and corrosion products precipitate inside cooling units, heat exchangers and pipeline networks affecting negatively efficiency of refinery’s equipment. In this work, a real plant data was collected from four cooling towers which is supplied the coolant to the crude distillation units of the refinery and also from the raw water supplier. The collected data was fitted by Langelier model to predict the tendency of cooling water for scale forming and activation of corrosion. The obtained result shows that the cooling water has a tendency to form scale (CaCO3 Precipitation) at cooling tower units. Also the feed water has the same tendency for scale forming.After analyzing the LSI (Langelier Saturation Index) results, the research team recommends the particular company to overcome this problem by installing a Reverse Osmosis (RO) plant for treating raw water to decrease the concentrations of total dissolved solids (TDS) which result scale and corrosion in the parts of cooling tower as an option to solve the problem.

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