PERFORMANCE EVALUATION OF COUNTER-FLOW WET COOLING TOWERS USING EXERGETIC ANALYSIS

2008 ◽  
Vol 32 (3-4) ◽  
pp. 499-512 ◽  
Author(s):  
A. Ataei ◽  
M. H. Panjeshahi ◽  
M. Gharaie
Keyword(s):  
Experimental Data ◽  
Performance Evaluation ◽  
Performance Improvement ◽  
Thermal Efficiency ◽  
Cooling Tower ◽  
Cooling Towers ◽  
Ambient Conditions ◽  
Counter Flow ◽  
Packing Materials ◽  
Exergetic Analysis

In this paper, performance evaluation of wet cooling tower is done. To achieve this aim, first, thermal behavior of counter-flow wet cooling tower is studied through a simulation model. The influence of the environmental conditions on the thermal efficiency of the cooling tower is investigated. The cooling tower performance is simulated in terms of varying air and water temperatures, and of the ambient conditions. This model allows the use of a variety of packing materials. Second, the exergetic analysis is applied to study the cooling tower potential of performance improvement. The model is validated against the experimental data.

Cooling Tower Performance Evaluation: Merkel, Poppe, and e-NTU Methods of Analysis

2005 ◽  
Vol 127 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Johannes C. Kloppers ◽  
Detlev G. Kro¨ger
Keyword(s):  
Performance Evaluation ◽  
Analytical Approach ◽  
Cooling Tower ◽  
Performance Characteristics ◽  
Cooling Towers ◽  
Ambient Conditions ◽  
Natural Draft ◽  
Ambient Humidity ◽  
Fill Material ◽  
Methods Of Analysis

The heat rejected and water evaporated in mechanical and natural draft cooling towers are critically evaluated by employing the Merkel, Poppe, and e–number-of-transfer-units e-NTU methods of analysis, respectively, at different operating and ambient conditions. The importance of using a particular method of analysis when evaluating the performance characteristics of a certain fill material and subsequently employing the same analytical approach to predict cooling tower performance is stressed. The effect of ambient humidity and temperature on the performance of cooling towers employing the Merkel, e-NTU, and Poppe methods of analysis are evaluated.

Assessment of Cooling Tower Discharge Recirculation and Dispersion Using CFD Techniques

2015 ◽  
Author(s):  
S. Pal ◽  
L. J. Peltier ◽  
A. Rizhakov ◽  
M. P. Kinzel ◽  
M. H. Elbert ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cooling Tower ◽  
Cross Flow ◽  
Bluff Bodies ◽  
Cooling Towers ◽  
Design Strategies ◽  
Worst Case ◽  
Buoyant Jets ◽  
Design Values ◽  
High Reynolds

The performance of cooling towers, whether operating by themselves, or in close vicinity of other cooling towers can be adversely affected by the re-ingestion of the cooling tower discharge into the tower intakes. The recirculation of the discharge from a wet cooling tower raises the wet bulb temperature of the air entering a wet cooling tower. Current design strategies, often account for this discharge re-ingestion issue, through a conservative adjustment to the far field ambient wet bulb temperature to calculate the actual intake wet bulb temperature. Critical applications, such as those related to nuclear safety applications where there is concern about cooling tower performance, may require more accurate and comprehensive assessment of the recirculation and dispersion of cooling tower discharge. Gaussian plume models alone are of limited use when dealing with discharges in the vicinity of large structures. This paper discusses the use of a computational fluid dynamics approach to evaluate worst case discharge recirculation effects in cooling towers. The bounding design values of tower intake wet bulb temperature increase due to recirculation (ingestion of tower’s own discharge), and interference (ingestion of another interfering tower’s discharge), are calculated considering the various conditions of cooling tower operation, ambient temperature, humidity and wind conditions. The RANS CFD model used in the study is evaluated against published experimental data for flow over bluff bodies at high Reynolds numbers, and experimental data on buoyant jets in cross flow.

Discuss of Important Issues in Numerical Simulation for Natural Draft Counter Flow Cooling Tower

2012 ◽  
Vol 516-517 ◽  
pp. 267-270
Author(s):  
Li Song ◽  
Rui Tian ◽  
Song Li ◽  
Ya Hui Wang
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Mass Transfer ◽  
Drop Size ◽  
Cooling Tower ◽  
Drop Diameter ◽  
Atmospheric Density ◽  
Counter Flow ◽  
Natural Draft ◽  
Calculation Results

natural draft counter flow cooling tower heat and mass transfer numerical simulation has been widely used to optimize the cooling tower design and to improve the thermal efficiency, but in published papers, a few important problems is not attracted attention, such as how does impact grid density to the calculation results; how does impact change of atmospheric density to the calculation results; drop diameter is an important parameter in numerical simulation, but it is not a exact experimental data, it is important to discuss how does impact drop size to the calculation results. This paper will explore and analyze these issues in the numerical simulation.

Estimating Cooling Towers for Power Plant Applications

2006 ◽  
Author(s):  
Hector L. Cruz
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cooling Tower ◽  
Arithmetic Function ◽  
Water Flow Rate ◽  
Mechanical Equipment ◽  
Cooling Towers ◽  
Ambient Conditions ◽  
The Cost ◽  
Basin Area

It has always been difficult to estimate size and cost of well designed counterflow induced-draught cooling towers due to the interrelationship of approach temperature and cooling range associated with each design. Attempts to estimate the cost of a tower by assessing currency per cell, per square foot, per gallon, or currency per other single metric, have never been sufficiently accurate due to the asymptotic nature of the approach temperature versus the tower size arithmetic function. To determine accurate qualitative metrics for cooling tower estimating purposes requires assessing two-variable second-order equations in water-flow-rate/approach-temperature, temperature-range/approach-temperature, wet-bulb-temperature/approach-temperature, and approach-temperature/cost. The design and therefore cost responds to the following variables; 1) Recirculating Water Flow Rate, 2) Inlet Wet Bulb Temperature (WBT), 3) Approach Temperature, and 4) Cooling Tower Range or Heat Duty. With the proper evaluation of these parameters they can be utilized to determine metrics to estimate the following parameters: 1) Number of Cells, 2) Basin Area, 3) Pump Power, 4) Fan Power, and 5) Costs (at today’s prices only). In addition, a percentage breakdown can be calculated for; 1) Structure, 2) Hardware, 3) Mechanical Equipment, 4) Labor, and 5) Miscellaneous items. Although developed for the power industry, the operative model, design, and qualified costing techniques are also valid for large petroleum and chemical process projects, provided the heat duty dissipated, ambient conditions, water quality and flow rate can be accurately predicted. A set of equations are developed which can be used to estimate the significant costs of a proposed cooling tower. Example calculations and data are presented in Annex A.

scholarly journals Heat and mass transfer performance and exergy performance evaluation of seawater cooling tower considering different inlet parameters

2021 ◽  
pp. 312-312
Author(s):  
Yang Yu ◽  
Xiaoni Qi ◽  
Xiaochen Hou ◽  
Xiaohang Qu ◽  
Qianjian Guo ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Thermal Efficiency ◽  
Cooling Tower ◽  
Exergy Efficiency ◽  
Optimum Operating ◽  
Transfer Performance ◽  
Cooling Towers ◽  
Air Speed ◽  
Exergy Performance

Cooling towers are important components within recirculating cooling water systems. Due to a shortage of freshwater resources, seawater cooling towers are widely used both in manufacturing and everyday life. This paper researches the mechanical draft counterflow wet seawater cooling tower (MDCWSCT), and establishes and verifies a detailed thermal performance calculation model. Referring to the second law of thermodynamics, the heat and mass transfer performance and exergy performance of the seawater cooling tower were studied. The effects of salinity, inlet air speed, and air wet-bulb temperature on the cooling efficiency, thermal efficiency, and exergy efficiency were analyzed. The results show that compared to the air wet-bulb temperature, changes in air speed have more influence on cooling and thermal efficiency under the study conditions. Moreover, the air wet-bulb temperature is the significant parameter affecting exergy efficiency. With an increase in salinity, the cooling, thermal, and exergy efficiency are about 2.40-8.25 %, 1.06-3.09 %, and 2.47-7.73 % lower than that of freshwater, respectively, within an air speed of 3.1-3.6 m/s. With an increase in salinity, the cooling, thermal, and exergy efficiency are about 2.28-8.47 %, 1.03-3.37 %, and 2.44-7.99 % lower than that of freshwater, respectively, within an air wet-bulb temperature of 25-27 ?. Through the exergy analysis of the seawater cooling tower, it is obvious that the heat and mass transfer performance and exergy performance can be improved by selecting the optimum operating conditions and appropriate packing specifications.

A Modified Analysis of Counter Flow Wet Cooling Towers

1997 ◽  
Vol 119 (3) ◽  
pp. 617-626 ◽  
Author(s):  
H. T. A. El-Dessouky ◽  
A. Al-Haddad ◽  
F. Al-Juwayhel
Keyword(s):  
Cooling Tower ◽  
Thermal Characteristics ◽  
Water Film ◽  
Lewis Number ◽  
Outlet Temperature ◽  
Cooling Towers ◽  
Logarithmic Mean ◽  
Counter Flow ◽  
Enthalpy Difference ◽  
Resistance To Heat

The paper describes a theoretical investigation for the steady-state counter flow wet cooling tower with modified definitions for both the number of transfer units and the tower thermal effectiveness. The modified number of transfer units is dependent on both air and water heat capacity. The effectiveness is defined by the tower cooling range and the approach to equilibrium. A new expression relating the tower effectiveness to the modified number of transfer units and the capacity rate ratio has been developed. The model considered the resistance to heat transfer in the water film, the nonunity of the Lewis number, and the curvature of the saturated air enthalpy curve. A procedure for implementing the model in designing or rating cooling towers has been outlined and demonstrated through illustrative examples. The model compares very satisfactorily with other methods such as Logarithmic Mean Enthalpy Difference (LMED) and conventional effectiveness—NTU. Within the ranges used, the obtained results showed that substantial errors varied from +4.289 to −2.536 percent can occur in calculating the cooled water outlet temperature, and errors from +42.847 to −16.667 percent can occur in estimating the tower thermal characteristics.

Performance Evaluation of an Experimental Turbojet Engine

2016 ◽  
Vol 0 (0) ◽  
Author(s):  
Selcuk Ekici ◽  
Yasin Sohret ◽  
Kahraman Coban ◽  
Onder Altuntas ◽  
T. Hikmet Karakoc
Keyword(s):  
Experimental Data ◽  
Performance Evaluation ◽  
Performance Assessment ◽  
Exergy Analysis ◽  
Design Parameters ◽  
Engine Exhaust ◽  
Turbine Engine ◽  
Turbojet Engine ◽  
Exergetic Analysis ◽  
And Performance

AbstractAn exergy analysis is presented including design parameters and performance assessment, by identifying the losses and efficiency of a gas turbine engine. The aim of this paper is to determine the performance of a small turbojet engine with an exergetic analysis based on test data. Experimental data from testing was collected at full-load of small turbojet engine. The turbojet engine exhaust data contains CO

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.

scholarly journals Energy efficiency indicators of cooling towers

2018 ◽  
Vol 11 (3) ◽  
pp. 217-221
Author(s):  
E. A. Lapteva ◽  
A. G. Laptev ◽  
M. L. Farakhov
Keyword(s):  
Mass Transfer ◽  
Energy Efficiency ◽  
Transfer Coefficient ◽  
Thermal Efficiency ◽  
Cooling Tower ◽  
Polymer Materials ◽  
Cooling Towers ◽  
Efficiency Criterion ◽  
Industrial Enterprises ◽  
Film Type

For selecting optimal regimes and design characteristics, an energy efficiency criterion of a mass transfer apparatus is considered, and on its basis, some particular cases of energy efficiency criteria for cooling towers, including the cases with a structured counter-current film-type packing, are obtained. The criteria include heat transfer efficiency in the gas and liquid phases, as well as kinetic characteristics of the process of cooling the water in blocks of film-type packings. Expressions are given for determination of thermal efficiencies in the gas (air) and liquid (water) phases of the cooling tower. Three notations for the energy efficiency criterion of cooling towers are obtained. In the first notation, the efficiency criterion is written down using the thermal efficiency of cooling the water; in the second notation, it is written down using the thermal efficiency of heating the air; in the third notation, it is written down via the transfer coefficient (mass transfer) and mean driving force in the form of an enthalpy difference. A notation of writing down the energy efficiency criterion for a film-type packing in the cooling tower with a volumetric mass transfer coefficient is presented. Irrigator blocks filled with structured film-type contact devices of various designs having an irrigation density of 12 m3/m2h and an air speed of 1.5 m/s are considered. Results of calculations of five types of structured packings are presented: tubular packing made of polyethylene net; metal packings VACU-PAK, PIRAPAK G, “Inzhekhim” IRG and segmentary-structured packing “Inzhekhim”. Values are obtained of the criterion of energy efficiency of these packings for cooling the water as well as the required height of irrigator blocks for a given temperature regime and hydraulic load. Values of the power expended for supplying the air to the irrigator blocks are determined and a histogram is plotted. It is concluded that modern domestic and foreign metal packings have high thermal and hydraulic efficiency and are recommended for use in mini-cooling towers (except for tubular packings made of polyethylene net). For reducing the cost of irrigator blocks, these can be made of polymer materials. Then such blocks of irrigators are recommended for creating a contact between the phases in large-scale cooling towers, which will significantly improve the efficiency of cooling the water at thermal power plants and industrial enterprises.

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