Modeling of a Rotary Dry Cooling Tower

1981 ◽  
Vol 103 (4) ◽  
pp. 715-719 ◽  
Author(s):  
J. A. Valenzuela ◽  
L. R. Glicksman
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Cooling Tower ◽  
Thick Layer ◽  
Hot Water ◽  
Rotating Disks ◽  
Air Stream ◽  
Additional Resistance ◽  
Dry Cooling Tower ◽  
Dry Cooling

A novel design of a rotary heat exchanger to be used as a dry cooling tower is described. The heat exchanger consists of a matrix of thin steel disks which rotate between a hot water bath and a forced draft air stream. On top of the water floats a 2 cm thick layer of oil which coats the rotating disks and thus eliminates evaporation. An analytical model of the heat exchanger was developed and validated with experimental measurements taken on a 1.5 m dia test section. The model was then used to determine the net effect of the oil on the heat transfer performance. Although the oil film that coats the disks presents an additional resistance to the transfer of heat, it also contributes to the heat capacity of the disks. It was found that the reduction in the overall heat transfer rate due to the presence of the oil is small, of the order of 5 to 10 percent.

Analysis of Heat Transfer Surface Geometries for Dry Cooling Tower Applications

1980 ◽  
Vol 102 (4) ◽  
pp. 807-812 ◽  
Author(s):  
Ali Montakhab
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cooling Tower ◽  
Heat Transfer Surface ◽  
Per Se ◽  
Fin Tube ◽  
Dry Cooling Tower ◽  
Heat Exchanger Surface ◽  
Dry Cooling

An analysis of heat exchanger surface geometries for the purpose of reducing dry cooling tower cost is presented. Two sets of results are derived. The first set can be used to evaluate heat transfer surface geometries in an attempt to select those most suitable for dry cooling tower applications. The second set of results can be used to direct research and development efforts toward developing better geometries for dry cooling tower applications. The first set of results is general and is applicable to all heat exchanger surface geometries. The second set is valid only for helical round or continuous fins having smooth, serrated, or cut fins and for staggered and in-line tube arrangements. The methods developed in this paper are not restricted to dry cooling towers per se, but are valid for other applications of fin tube heat exchangers as well.

Preliminary Design of Dry Cooling Tower for the Closed Cycle Gas Turbine HTGR

1981 ◽  
Author(s):  
A. Montakhab
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Cooling Tower ◽  
Waste Heat ◽  
Cross Flow ◽  
Preliminary Design ◽  
Closed Cycle ◽  
Natural Draft ◽  
Dry Cooling Tower ◽  
Dry Cooling

Because of its relatively high coolant temperature, the closed cycle gas turbine HTGR is well adapted to dry cooling and its waste heat can be rejected with relatively low cost. The preliminary design of natural-draft dry cooling towers for a 1200 MW(e) GT-HTGR is presented. The effects of air approach velocity, capacity rates of air and water mediums, and number of heat exchanger cross flow passes on salient tower and heat exchanger dimensions are studied. Optimum tower designs are achieved with three cross flow passes for the heat exchanger, resulting in a simultaneous minimization of tower height, heat exchanger surface area and circulating water pumping power. Four alternative tower designs are considered and their relative merits are compared. It is concluded that the 1200 MW(e) plant can be cooled by a single tower design which is well within the present state of the natural-draft dry cooling tower technology. In comparison, the fossil-fired or HTGR steam plants of the same output is shown to need three such towers.

Details Study of Ambient Wind Effect on Heat Dissipation Capacity of Thermal-Powerplant Dry Cooling-Towers

2014 ◽  
Author(s):  
Masoud Darbandi ◽  
Ali Behrouzifar ◽  
Ahmad Mirhashemi ◽  
Hossein Salemkar ◽  
Gerry E. Schneider
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Heat Dissipation ◽  
Cooling Tower ◽  
Wind Effect ◽  
Circulating Water ◽  
Wind Velocities ◽  
Computational Fluid Dynamics Cfd ◽  
Dry Cooling Tower ◽  
Dry Cooling

Thermal powerplants report a reduction in their dry cooling tower performances due to surrounding wind drafts. Therefore, it is very important to consider the influence of wind velocity in cooling tower design; especially in geographical points with high wind conditions. In this regard, we use the computational fluid dynamics (CFD) tool and simulate a dry cooling tower in different wind velocities of 0, 5 and 10 m/s. To extend our calculations; we also consider the temperature variation of circulating water through the tower heat exchanger or deltas one-by-one. We show that some heat exchangers around the tower cannot reduce the circulating water temperature sufficiently. This causes an increase in the mean temperature of those heat exchangers. The worst performances can be attributed to heat exchanger located on side wind places. We will discuss the detail performance of each delta and their assembly in draft wind conditions. This study suggests some effective ways to overcome thermal-performance of cooling tower in wind conditions.

scholarly journals Simultaneous effects of water spray and crosswind on performance of natural draft dry cooling tower

2013 ◽  
Vol 17 (2) ◽  
pp. 443-455 ◽  
Author(s):  
Hossein Ahmadikia ◽  
Mohsen Soleimani ◽  
Ehsan Gholami
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cooling Tower ◽  
Wind Condition ◽  
Water Spray ◽  
Natural Draft ◽  
Spray System ◽  
Dry Cooling Tower ◽  
Dry Cooling

To investigate the effect of water spray and crosswind on the effectiveness of the natural draft dry cooling tower (NDDCT), a three-dimensional model has been developed. Efficiency of NDDCT is improved by water spray system at the cooling tower entrance for high ambient temperature condition with and without crosswind. The natural and forced heat convection flow inside and around the NDDCT is simulated numerically by solving the full Navier-Stokes equations in both air and water droplet phases. Comparison of the numerical results with one-dimensional analytical model and the experimental data illustrates a well-predicted heat transfer rate in the cooling tower. Applying water spray system on the cooling tower radiators enhances the cooling tower efficiency at both no wind and windy conditions. For all values of water spraying rate, NDDCTs operate most effectively at the crosswind velocity of 3m/s and as the wind speed continues to rise to more than 3 m/s up to 12 m/s, the tower efficiency will decrease by approximately 18%, based on no-wind condition. The heat transfer rate of radiator at wind velocity 10 m/s is 11.5% lower than that of the no wind condition. This value is 7.5% for water spray rate of 50kg/s.

Experimental Investigation of Heat Transfer Enhancement by Using Different Number of Fins in Circular Tube

2018 ◽  
Vol 6 (3) ◽  
pp. 1-12
Author(s):  
Kamil Abdul Hussien
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Cold Water ◽  
Finned Tube ◽  
Hot Water ◽  
Copper Tube ◽  
Smooth Tube ◽  
Tube Heat Exchanger ◽  
Mass Flow Rates ◽  
Flow Heat

Abstract-The present work investigates the enhancement of heat transfer by using different number of circular fins (8, 10, 12, 16, and 20) in double tube counter flow heat exchanger experimentally. The fins are made of copper with dimensions 66 mm OD, 22 mm ID and 1 mm thickness. Each fin has three of 14 mm diameter perforations located at 120o from each to another. The fins are fixed on a straight smooth copper tube of 1 m length, 19.9 mm ID and 22.2 mm OD. The tube is inserted inside the insulated PVC tube of 100 mm ID. The cold water is pumped around the finned copper tube, inside the PVC, at mass flow rates range (0.01019 - 0.0219) kg/s. The Reynold's number of hot water ranges (640 - 1921). The experiment results are obtained using six double tube heat exchanger (1 smooth tube and the other 5 are finned one). The results, illustrated that the heat transfer coefficient proportionally with the number of fin. The results also showed that the enhancement ratio of heat transfer for finned tube is higher than for smooth tube with (9.2, 10.2, 11.1, 12.1 13.1) times for number of fins (8, 10, 12, 16 and 20) respectively.

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