Research Note: Study of Degradation of Dry Cooling Tower Performance Under Wind Conditions and Method for Tower Efficiency Enhancement (original) (raw)
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2014
In a steam power plant, the temperature of the cooling water leaving the condenser for recyclingshould decrease. This is achieved in a cooling tower. The Heller cooling tower does not require waterfor operation, thus, it is a suitable system for use in thermal power plants throughout Iran. Wind is anenvironmental factor that unfavorably affects the performance of a cooling tower. Previous studieshave not considered real prevailing conditions appropriately; their conclusions are incomplete and, attimes, contradictory. The present field study of the cooling tower at Montazer-Ghaem Power Plant inthe city of Karaj in Iran investigated the effect of wind on the thermal performance of the coolingtower. Wind velocity was measured using blade-and-cup type digital anemometers. The direction ofthe wind around the cooling tower was determined using tufts. Ultrasonic flow meters and resistancethermometers were used to measure the flow rates and temperatures of the water at the inlet and outlet,...
2017
This article aims to study the thermal performances of four different natural draft cooling towers under crosswind condition. The windbreakers and the oblique exit plane have been simultaneously included in the structure of the new cooling tower. A finite volume method using SIMPLE algorithm was used to simulate the flow field around each cooling tower. The thermal performance of the new geometry has been compared with those of others for the generally investigated wind velocity profile for 10 m/s, and also two uniform wind velocities for 3 and 7 m/s. The cooling capacity of the cooling tower utilizing windbreakers and the oblique exit plane was predicted as 98.3% of the design value in the presence of generally studied wind velocity profile of 10 m/s, while that of the cooling tower utilizing windbreakers was predicted as 93.5%. Of course, the percentage of the thermal improvements of the different restoring strategies are sensitive to the profile of an approaching wind. The uniform wind velocity decreases the thermal efficiency of the cooling tower more than the distributed one, while the restoring strategies using windbreakers provide a higher percentage of thermal improvements in the presence of uniform wind velocity.
Iranian Journal of Science and Technology, Transactions of Mechanical Engineering, 2018
The performance of natural draft dry cooling towers (NDDCTs) depends on the environmental conditions. Crosswind is known to have the most destructive effect, whereas the ambient temperature is marked as the next. A 3-D numerical model was developed to investigate the thermal performance of a single as well as three aligned units of NDDCTs under crosswind conditions. The computed results showed major discrepancies between computed velocity patterns and pressure fields around three aligned towers and those of the single tower due to windshield effect of neighboring cooling towers. The thermal performance losses for the single tower under crosswind showed higher values compared with those of towers in the aligned arrangement. The best thermal performance of three aligned NDDCTs was achieved when the crosswind was directed along the towers' connection line.
Experimental Study Of Wind Effects On The Airflow Of Natural Draft Wet Cooling Towers
2010
Natural draft cooling towers may enhance the overall performance of a thermal or a nuclear power station by providing coolant water to the condenser at a reduced temperature. The cooling tower thermal performance and its air flow inside the tower are influenced by the prevailing cross winds which in turn are amplified or damped by the flowconditioning characteristics of surrounding structures, building and terrains in the relative proximity and orientation to the tower. These characteristics were investigated in the No-1 cooling tower at the Mount Piper Power Station near Sydney in Australia. The tower was instrumented using thermocouples and directional anemometers to measure air velocities and temperatures both inside and outside of the tower over three months period. The test results have indicated that surrounding structures and their relative orientations to the tower and wind directions affect on the air flow rate inside a tower and should be considered at the design stage..
Enhancing performance of wet cooling towers
Energy Conversion and Management, 2007
The effect of windbreak walls on the thermal performance of natural draft wet cooling towers (NDWCT) under crosswind has been investigated numerically. The three dimensional CFD model has utilised the standard k-e turbulence model as the turbulence closure to quantify the effects of the locations and porosities of the wall on the NDWCT thermal performance. Moreover, the improvement in the NDWCT thermal performance due to windbreak walls has been examined at different crosswind directions. Results from the current investigation have demonstrated that installing solid impermeable walls in the rain zone results in degrading the performance of the NDWCT. However, installing solid walls at the inlet of the NDWCT has enhanced the NDWCT performance at all of the investigated crosswind velocities. Similarly, installing walls with low porosity has shown improvement in the performance of the NDWCT. A reduction of 0.5-1 K in the temperature of the cooling water coming from the tower to the condenser has been achieved at all of the investigated crosswind velocities by installing porous walls both inside and outside the rain zone.
The performance of natural draft dry cooling towers under crosswind: CFD study
International Journal of Energy Research, 2004
The thermal performance of a natural draft dry cooling tower (NDDCT) under a crosswind has been investigated using a general-purpose CFD code. A three-dimensional study using the standard k–ε turbulence model to simulate airflow in and around an NDDCT has been conducted. A parametric study has been carried out to examine the effect of crosswind velocity profile and air dry-bulb temperature on the thermal performance of an NDDCT. Two approaches have been considered in this study to quantify the crosswind effect. Firstly, simulations have been conducted at the nominal conditions and crosswind effect has been represented by thermal effectiveness parameter. Secondly, the ejected heat from the NDDCT has been maintained at a constant value (285 MW) and the crosswind effect has been represented by the change in the cooling tower approach parameter. After quantifying the effect of the crosswind on the thermal performance, windbreak walls have been introduced as a means of reducing this effect. The results in this paper show the importance of considering the crosswind velocity profile. Moreover, the introduction of windbreak walls has indicated an improvement in reducing the thermal performance losses due to the crosswind. Copyright © 2004 John Wiley & Sons, Ltd.
Response of Cooling Tower to Wind Loads
The IUP Journal of Structural Engineering, 2023
The structural response of cooling tower shell under wind loading is objective of current study. The calculated wind pressure is applied on cooling tower at different height and circumferential angles. The analysis is carried out for different shell thicknesses using FEA, the response of cooling tower shell is observed in terms of deflection, hoop and meridional forces at 0 degree meridian. The circumferential pressure distribution given in IS 11504: 1985 code are expressed as Fourier cosine series, in the present study the calculation is carried out for 15 degree interval and is compared with the coefficients obtained from IS 875 (Part 3): 1987. It is observed that the deflection of cooling tower shell decreases whereas the hoop and meridional force increases, with increase in shell thicknesses. The hoop and meridional forces are not much affected above throat level for different shell thickness.
Integration and Application of Passive Cooling Within a Wind Tower
ASHRAE, 2014
Increasing emphasis on reducing power consumption has raised public awareness of natural and renewable energy resources, particularly the integration of passive cooling systems in buildings such as wind towers. Wind towers have been in existence in various forms for centuries as a non-mechanical means of providing indoor ventilation. In hot conditions where there is a relatively low difference between internal and external temperatures, the cooling capabilities of wind towers which depend mainly on the structure design itself are inadequate. Therefore it is essential to cool the air in order to reduce the building heat load and improve the thermal comfort of its occupants during the summer months. The aim of this work was to incorporate heat transfer devices in a wind tower to meet the internal comfort criteria in extreme external conditions. Heat transfer devices were installed inside the passive terminal of the wind tower unit, highlighting the potential to achieve minimal restriction in the external air flow stream while ensuring maximum contact time, thus optimising the cooling duty of the device. Computational Fluid Dynamics (CFD) modelling and experimental wind tunnel testing were conducted to investigate the performance of a wind tower system incorporating the heat transfer device arrangement. Results have indicated that the achieved indoor air speed was reduced by 28 – 52 % following the integration of the heat transfer device configurations. Furthermore, the study concluded that the proposed cooling system was capable of reducing the air temperatures by up to 12 K, depending on the configuration and operating conditions. Good agreement was observed between the CFD simulation and the experimental results.
Simultaneous effects of water spray and crosswind on performance of natural draft dry cooling tower
Thermal Science, 2013
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 effi...
Numerical analysis of wind flow influence on thermal loading inside dry cooling towers
2009
In this paper, the set of 3-dimansional equations for the incompressible air flow is combined with the equation for the temperature field are solved using FEM (Finite Element Method). Commercial FEM software is applied to simulate the changes in the velocity components, pressure and temperature distribution inside a Natural Draught Dry-Cooling tower due to the wind flow at supercritical Reynolds number. This Dry-Cooling tower is located in the SHAZAND power station, which is under operation in north part of IRAN (ARAK province). The utilized numerical model solves the governing equations for wind flow on a three-dimensional unstructured Finite Element mesh. Using unstructured meshes provides the merit of accurate geometrical modeling of the curved boundaries of the Dry-cooling tower. Satisfactory results are obtained by the use of proper boundary conditions.