scholarly journals On Thermal Performance of Seawater Cooling Towers

2010 ◽  
Author(s):  
Mostafa H. Sharqawy ◽  
John H. Lienhard ◽  
Syed M. Zubair
Keyword(s):  
Thermal Conductivity ◽  
Power Generation ◽  
Thermal Performance ◽  
Cooling Tower ◽  
Cooling Towers ◽  
Governing Equations ◽  
Detailed Model ◽  
Salt Deposition ◽  
Transfer Processes ◽  
Mass Transfer Processes

Seawater cooling towers have been used since the 1970’s in power generation and other industries, so as to reduce the consumption of freshwater. The salts in seawater are known to create a number of operational problems including salt deposition, packing blockage, corrosion, and certain environmental impacts from salt drift and blowdown return. In addition, the salinity of seawater affects the thermophysical properties which govern the thermal performance of cooling towers, including vapor pressure, density, specific heat, viscosity, thermal conductivity and surface tension. In this paper, the thermal performance of seawater cooling towers is investigated using a detailed model of a counterflow wet cooling tower. The model takes into consideration the coupled heat and mass transfer processes and does not make any of the conventional Merkel approximations. In addition, the model incorporates the most up-to-date seawater properties in the literature. The model governing equations are solved numerically and its validity is checked by data in the literature. Based on the results of the model, a correction factor is obtained which characterizes the degradation of the cooling tower effectiveness when seawater is used.

scholarly journals On Thermal Performance of Seawater Cooling Towers

2010 ◽  
Vol 133 (4) ◽  
Author(s):  
Mostafa H. Sharqawy ◽  
John H. Lienhard ◽  
Syed M. Zubair
Keyword(s):  
Thermal Conductivity ◽  
Thermal Performance ◽  
Cooling Tower ◽  
Cooling Towers ◽  
Governing Equations ◽  
Detailed Model ◽  
Salt Deposition ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Seawater Salinity

Seawater cooling towers have been used since the 1970s in power generation and other industries, so as to reduce the consumption of freshwater. The salts in seawater are known to create a number of operational problems, including salt deposition, packing blockage, corrosion, and certain environmental impacts from salt drift and blowdown return. In addition, the salinity of seawater affects the thermophysical properties that govern the thermal performance of cooling towers, including vapor pressure, density, specific heat, viscosity, thermal conductivity, and surface tension. In this paper, the thermal performance of seawater cooling towers is investigated using a detailed model of a counterflow wet cooling tower. The model takes into consideration the coupled heat and mass transfer processes and does not make any of the conventional Merkel approximations. In addition, the model incorporates the most up-to-date seawater properties in the literature. The model governing equations are solved numerically, and its validity is checked against the available data in the literature. Based on the results of the model, a correction factor that characterizes the degradation of the cooling tower effectiveness as a function of seawater salinity and temperature approach is presented for performance evaluation purposes.

scholarly journals Thermal Performance Evaluation of Seawater Cooling Towers

2011 ◽  
Author(s):  
Mostafa H. Sharqawy ◽  
Iqbal S. Husain ◽  
Syed M. Zubair ◽  
John H. Lienhard
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Fresh Water ◽  
Thermal Performance ◽  
Operating Conditions ◽  
Thermal Design ◽  
Cooling Towers ◽  
Detailed Model ◽  
Transfer Processes ◽  
Mass Transfer Processes

Seawater has been used for long time as a cooling fluid in heat exchangers to reduce fresh water usage in industry and power plants. The thermophysical properties of seawater are different from those of fresh water due to the salt content or salinity. This difference is sufficient to affect the heat and mass transfer processes which in turn change the thermal performance. Thermal design of fresh water cooling towers is described in detail in many textbooks and handbooks. However, only a rule of thumb is frequently used for designing of seawater cooling towers. This rule recommends degrading the tower performance by approximately 1% for every 10,000 ppm of salts in the feed water. In this paper, the thermal performance of seawater cooling towers is presented using a detailed model of counterflow wet cooling towers which takes into consideration the coupled simultaneous heat and mass transfer processes and uses state-of-the-art seawater properties from the literature. The model governing equations are solved numerically and the validity of this model is checked using new experimental data that has been measured using a bench top counterflow seawater cooling tower. The effect of the variation of seawater salinity as well as other operating conditions on the effectiveness and Merkel number is investigated.

Computer Simulation of Transport Phenomena in Evaporative Cooling Towers

1988 ◽  
Vol 110 (2) ◽  
pp. 190-196 ◽  
Author(s):  
D. J. Benton ◽  
W. R. Waldrop
Keyword(s):  
Power Plants ◽  
Field Data ◽  
Cooling Tower ◽  
Operating Conditions ◽  
Cooling Towers ◽  
Governing Equations ◽  
Cooling Process ◽  
Transfer Processes ◽  
Finite Integral ◽  
Simultaneous Heat

A computer model of the simultaneous heat, mass, and momentum transfer processes occurring throughout an entire cooling tower is described in this paper. The model includes the flexibility to analyze the several configurations, fill arrangements, and flow distributions commonly used by the power industry. The fundamental governing equations are solved using a finite-integral technique to provide a quasi-two-dimensional description of the flow and cooling process within the tower. The model has been successfully compared with field data from cooling towers at three TVA power plants as well as data from other utilities. Each of these towers was significantly different in design, thereby demonstrating the versatility of the model for correctly predicting the cooling performance of mechanical and natural draft towers, as well as crossflow and counterflow orientations, for a range of meteorological and plant operating conditions.

scholarly journals An analytical model on thermal performance evaluation of counter flow wet cooling tower

2017 ◽  
Vol 21 (6 Part A) ◽  
pp. 2491-2501 ◽  
Author(s):  
Qian Wang ◽  
Pei-Hong Wang ◽  
Zhi-Gang Su
Keyword(s):  
Analytical Model ◽  
Thermal Performance ◽  
Power Plants ◽  
Cooling Tower ◽  
Cooling Towers ◽  
Counter Flow ◽  
Water Surface Temperature ◽  
Mass Transfer Processes ◽  
Proposed Model ◽  
Simultaneous Heat

This paper proposes an analytical model for simultaneous heat and mass transfer processes in a counter flow wet cooling tower, with the assumption that the enthalpy of the saturated air is a linear function of the water surface temperature. The performance of the proposed analytical model is validated in some typical cases. The validation reveals that, when cooling range is in a certain interval, the proposed model is not only comparable with the accurate model, but also can reduce computational complexity. In addition, with the proposed analytical model, the thermal performance of the counter flow wet cooling towers in power plants is calculated. The results show that the proposed analytical model can be applied to evaluate and predict the thermal performance of counter flow wet cooling towers.

An Analytical Approach to the Heat and Mass Transfer Processes in Counterflow Cooling Towers

2006 ◽  
Vol 128 (11) ◽  
pp. 1142-1148 ◽  
Author(s):  
Chengqin Ren
Keyword(s):  
Mass Transfer ◽  
Differential Equations ◽  
Heat And Mass Transfer ◽  
Analytical Model ◽  
Operating Conditions ◽  
Cooling Towers ◽  
Accurate Analysis ◽  
Transfer Resistance ◽  
Transfer Processes ◽  
Mass Transfer Processes

Quick and accurate analysis of cooling tower performance, outlet conditions of moist air, and parameter profiles along the tower height is very important in rating and design calculations. This paper developed an analytical model for the coupled heat and mass transfer processes in counterflow cooling towers based on operating conditions more realistic than most conventionally adopted Merkel approximations. In modeling, values of the Lewis factor were not necessarily specified as unity. Effects of water loss by evaporation and water film heat transfer resistance were also considered in the model equations. Within a relatively narrow range of operating conditions, the humidity ratio of air in equilibrium with the water surface was assumed to be a linear function of the surface temperature. The differential equations were rearranged and an analytical solution was developed for newly defined parameters. The analytical model predicts the tower performances, outlet conditions, and parameter profiles quickly and accurately when comparing with the numerical integration of the original differential equations.

Effect of Wind Directions on the Thermal Performance of Three Aligned NDDCT: Parallel and Perpendicular Directions

2012 ◽  
Vol 232 ◽  
pp. 218-222
Author(s):  
Samad Ghafarigousheh ◽  
Ali Akbar Golneshan
Keyword(s):  
Numerical Model ◽  
Thermal Performance ◽  
Cooling Tower ◽  
Cooling Towers ◽  
Flow Parameters ◽  
Pressure Fields ◽  
Connection Line

In this paper a 3-D numerical model is used to investigate the thermal performance of a three aligned unit of NDDCT under crosswind condition. The computed results show that, there are major differences in computed velocity patterns and pressure fields around the cooling tower due to neighboring of a number of cooling towers will result considerable changes in computed flow parameters hence; the thermal performance losses for the single tower under crosswind are superior to those when this towers are incorporated in aligned arrangement. Results also show that the best thermal performance of the three aligned NDDCT is achieved when the crosswind is directed along the towers connection line.

Thermal performance analysis of a closed wet cooling tower

2007 ◽  
Vol 221 (3) ◽  
pp. 139-150 ◽  
Author(s):  
V. D. Papaefthimiou ◽  
T. C. Zannis ◽  
E. D. Rogdakis
Keyword(s):  
Thermal Performance ◽  
Cooling Tower ◽  
Water Mass ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Water Stream ◽  
Detailed Model ◽  
Air Mass ◽  
Mass Flowrate ◽  
Closed Wet Cooling Tower

A detailed model was developed and employed to examine the thermal performance of a closed wet cooling tower. The model is capable of predicting the variation of air thermodynamic properties, sprayed and serpentine water temperature as well as heat transfer rates exchanged between air and falling water stream inside the indirect wet cooling tower. The reliability of simulations was tested against experimental data obtained from the literature. A parametric study was conducted to evaluate the thermal behaviour of the indirect cooling tower under various air mass flowrates, serpentine water mass flowrates and inlet temperatures. The results of the theoretical investigation revealed an increase in cooling capacity and percentage loss of sprayed water due to evaporation, with increasing air mass flowrate. On the other hand, the increase of serpentine water mass flowrate resulted in slight increase in the overall temperature reduction of serpentine water. The effect of variable serpentine water inlet temperature on thermal performance of the indirect wet cooling tower was insignificant compared to other cases.

scholarly journals Measurement point density and measurement methods in determining the geometric imperfections of shell surfaces

2018 ◽  
Vol 105 (1) ◽  
pp. 19-28
Author(s):  
Rafał Kocierz ◽  
Michał Rębisz ◽  
Łukasz Ortyl
Keyword(s):  
Laser Scanning ◽  
Cooling Tower ◽  
Optimal Number ◽  
Cooling Towers ◽  
Geometric Imperfections ◽  
Detailed Model ◽  
Exterior Surface ◽  
Shell Deformation ◽  
Accuracy Of Measurements ◽  
Correct Representation

Abstract In geodetic measurements of deformations in shell cooling towers, an important factor is to optimize the number of points representing the exterior surface of the shell. The conducted analyses of damage to such structures proved that cooling towers exhibited shell deformation consisting of irregular vertical waves (three concavities and two convexities), as well as seven horizontal waves. On this basis, it is claimed that, in accordance with the Shannon theorem, the correct representation of the generated waves requires the measurement of the cooling tower shell in a minimum of 12 vertical and 14 horizontal sections. Such density of the points may not be sufficient to represent local imperfections of the shell. The article presents the results of test measurements and their analysis, which were conducted to verify the assumptions as to the optimal number of measurement points for the shell of a cooling tower. The evaluation was based on a comparative analysis of the data obtained by the Terrestrial Laser Scanning (TLS) method, creating a very detailed model of geometric imperfections in an actual cooling tower with a height of 100 m. Based on the data obtained by the TLS method, point grids of various density were generated. An additional measurement of the cooling tower shell deformation was performed using a precise electronic total station with reflectorless measurement option. Therefore, it was possible to assess the accuracy of measurements by laser scanning in relation to measurements obtained by reflectorless total stations.

Sign in / Sign up

Export Citation Format

Share Document