HEAT AND MASS TRANSFER IN WETTED-SURFACE COOLING TOWERS

1978 ◽  
Author(s):  
K. K. Niyogi ◽  
G. F. Pavlenco
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Cooling Towers ◽  
Surface Cooling

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.

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.

scholarly journals Experimental investigation of heat and mass transfer of an annular impinging jet

2021 ◽  
Vol 2039 (1) ◽  
pp. 012028
Author(s):  
M V Philippov ◽  
I A Chokhar ◽  
V V Terekhov ◽  
V I Terekhov ◽  
I N Baranov
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Experimental Study ◽  
Heat And Mass Transfer ◽  
Impinging Jet ◽  
Surface Cooling ◽  
Effective Surface ◽  
Flow And Heat Transfer ◽  
Annular Jet ◽  
Characteristic Features

Abstract This work presents an experimental study of a turbulent flow and heat transfer of an annular impinging jet for organizing effective surface cooling. Heat and mass transfer of the impinging annular jet was studied at Re = 5500. At that, a distance from the nozzle to the wall was varied. The focus was made on configurations with small nozzle-to-wall distances. It is shown that, depending on the indicated distance, fundamentally different flow regimes with characteristic features of heat transfer distribution are observed.

Heat and mass transfer in natural draft cooling towers

2013 ◽  
Vol 86 (5) ◽  
pp. 1072-1082 ◽  
Author(s):  
M. M. Hemmasian Kashani ◽  
K. V. Dobrego
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Cooling Towers ◽  
Natural Draft

Numerical Modeling of Wet Cooling Towers—Part 1: Mathematical and Physical Models

1983 ◽  
Vol 105 (4) ◽  
pp. 728-735 ◽  
Author(s):  
A. K. Majumdar ◽  
A. K. Singhal ◽  
D. B. Spalding
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Water Temperature ◽  
Heat And Mass Transfer ◽  
Computer Code ◽  
Hot Water ◽  
Physical Models ◽  
Cooling Towers ◽  
Transfer Rates ◽  
The Mathematical Model

The paper discusses the limitations of current practices of evaluating thermal performance of wet cooling towers and describes a more advanced mathematical model for mechanical and natural draft cooling towers. The mathematical model computes the two-dimensional distributions of: air velocity (two components); temperature, pressure, and moisture content; and water temperature. The downward direction of water flow is presumed. The local interphase heat and mass transfer rates are calculated from empirical correlations for which two options are provided. In the first option, only one constant (Ka, based on Merkel’s approximations) is employed; in the second option, two separate constants for heat and mass transfer are used. Boundary conditions can be either of the prescribed cooling range or of the prescribed hot water temperature types. The governing equations are solved by a finite difference method. The model is embodied into a computer code (VERA2D) which is applicable for the natural and mechanical draft towers of both the crossflow and counterflow arrangements. Several applications of the code are described in Part II of the paper.

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