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.

Analysis of Heat, Mass, and Momentum Transfer in the Rain Zone of Counterflow Cooling Towers

1999 ◽  
Vol 121 (4) ◽  
pp. 751-755 ◽  
Author(s):  
E. de Villiers ◽  
D. G. Kro¨ger
Keyword(s):  
Momentum Transfer ◽  
Cooling Tower ◽  
Mechanical Energy ◽  
Performance Evaluations ◽  
Cooling Towers ◽  
Droplet Deformation ◽  
One Dimensional ◽  
Mechanical Energy Loss ◽  
Simplifying Assumptions ◽  
Semi Empirical

The rate of heat, mass, and momentum transfer in the rain zone of three counterflow cooling tower geometries is analyzed using simplifying assumptions and numerical integration. The objective of the analysis is to generate equations for use in a one-dimensional mathematical cooling tower performance evaluations. Droplet deformation is taken into account and momentum transfer is calculated from the air flow’s mechanical energy loss, caused by air-droplet interaction. A comparison of dimensionless semi-empirical equations and experimental data demonstrates the method’s capability to predict the pressure drop in a counterflow rain zone.

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.

scholarly journals An Analytical Approach to Wet Cooling Towers Based on Functional Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Guo Qianjian ◽  
Xiaoni Qi ◽  
Zheng Wei ◽  
Peng Sun
Keyword(s):  
Functional Analysis ◽  
Temperature Distribution ◽  
Analytical Solution ◽  
Cooling Tower ◽  
Transfer Model ◽  
Cooling Towers ◽  
Contraction Mapping Theorem ◽  
Uniqueness Of The Solution ◽  
Linear Differential ◽  
Analytical Expressions

An analytical solution for computing the temperature distribution of air and water over the height through the cooling tower is so complex that finding the exact solution takes too much time. The purpose of this paper is to present efficient and accurate analytical expressions for the heat and mass transfer model in cooling towers. Based on the method of functional analysis, we derived an analytical solution for temperature distribution of water and air by using the method of solving linear differential equations. The error estimation, the existence, and uniqueness of the solution are given by using Banach contraction mapping theorem. The basic equation of the model on the basis of the additional assumptions on the cooling tower is solved, and the outlet parameters are also obtained.

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.

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.

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.

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.

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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