Effect of Wind on Thermal Performance of Heller Dry Cooling Tower (original) (raw)
Related papers
2015
Wind can adversely affect the thermal performance of a dry cooling tower. In this field study, performance of Heller cooling tower and the use of guide vanes cascade at the intakes of the periphery cooling sectors, which are parallel to the wind direction and have inadequate thermal performance, for enhancement of the cooling tower performance under wind conditions were investigated. Wind velocity around the cooling tower and water flow rates and temperatures at the cooling tower inlet and outlet were measured. It was observed that the air suction through the tower prevented the flow separation at the radiators locations on the tower periphery. Moreover, with increase in wind velocity, the performance of sectors parallel to the wind direction on the tower periphery and those at the back of the tower deteriorated. However, the better airflow distribution over the wind facing cooling sectors resulted in about 20% increase in the thermal efficiency of these sectors with increased wind ...
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..
Cooling performance of Persian wind towers
Eco-Architecture IV, 2012
In hot-dry regions of Iran typical buildings are made of mud and fired brick. Temperature, humidity and airflow control comfort within such buildings. These passive cooling buildings use nature's elements in providing comfort to people: night ventilation, evaporative cooling and ground cooling. High-rise wind towers (badgirs) above the roofs catch the passing winds and channel them down to the ground and basement spaces in order to cool the internal spaces on summer days. In this paper Persian wind towers and their passive cooling system are described. Results from numerical analysis of wind towers with four different heights are presented. Parameters such as mass flow and temperature in wind towers are studied and the effects of their heights and the orientation and velocity of wind on these parameters are reported.
Elsevier, 2013
Increasing focus on reducing energy consumption has raised public awareness of renewable energy resources, particularly the integration of natural ventilation devices in buildings such as wind towers. The purpose of this paper was to compare the traditional evaporative wind tower technique with a proposed wind tower system consisting of heat pipes. Computational Fluid Dynamics (CFD) was used to develop a numerical model of a wind tower system and simulate the air flow pattern around and through the device. A baseline heat exchanger section containing cylindrical heat pipes was constructed to simulate the multiphase flow behaviour of two-phase heat pipe working fluids including water and ethanol. Heat transfer rate was obtained at 113 and 106 W for water and 72 and 116 W for ethanol respectively. The second part of the study incorporated the cylindrical heat pipes within the control domain of a roof-mounted wind tower, highlighting the potential to achieve minimal restriction in the external air flow stream while ensuring maximum contact time, thus optimizing the cooling duty of the device. A comparison was established with the conventional evaporative cooling methodology. The proposed cooling system consisting of heat pipes was capable of reducing the air temperatures by 12–15 K, depending on the configuration and operating conditions. The technology presented here is subject to IP protection under the QNRF funding guidelines.
Applied Thermal Engineering, 2012
A thermodynamic model was developed and used to assess the sensitivity of thermal performance characteristics of a closed wet cooling tower to inlet air conditions. In the present study, three cases of different ambient conditions are considered: In the first case, the average mid-winter and mid-summer conditions as well as the extreme case of high temperature and relative humidity, in Athens (Greece) during summer are considered according to the Greek Regulation for Buildings Energy Performance. In the second case, the varied inlet air relative humidity while the inlet air dry bulb temperature remains constant were taken into account. In the last case, the effects on cooling tower thermal behaviour when the inlet air wet bulb temperature remains constant were examined. The proposed model is capable of predicting the variation of air thermodynamic properties, sprayed water and serpentine water temperature inside the closed wet cooling tower along its height. The reliability of simulations was tested against experimental data, which were obtained from literature. Thus, the proposed model could be used for the design of industrial and domestic applications of conventional air-conditioning systems as well as for sorption cooling systems with solid and liquid desiccants where closed wet cooling towers are used for precooling the liquid solutions.
Performance of cooling tower in south of Tunisia
Building and Environment, 2004
This paper presents a mathematical model for the numerical prediction of the performance of cross ow cooling towers. The mathematical model is based on the heat and mass transfer equations. The leading parameters are the Lewis number Le, the number of transfer units U , the percentage of water evaporation, the water losses and the tower e ciency. This model is used to predict the thermal behavior of six cooling towers located in the South of Tunisia. These towers are employed to decrease the temperature of geothermal water from 65 • C to 34 • C using a cross ow air. The total ow rate of water is 900 kg s −1 and that of dry air is 1840 kg s −1. Several experimental data have been collected on site, in order to adopt the mathematical model. The model has been used to predict the performance of cooling towers in terms of the meteorological conditions prevailing in the South of Tunisia. An optimal water loss quantity has been determined. On an annual basis, the actual water losses by evaporation represent 4% of the total water ow rate which correspond to 10 6 m 3 year −1. This represents the annual consumption of 20 000 inhabitants.
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.
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.
Thermodynamic study of wet cooling tower performance
International Journal of Energy Research, 2006
An analytical model was developed to describe thermodynamically the water evaporation process inside a counter-flow wet cooling tower, where the air stream is in direct contact with the falling water, based on the implementation of the energy and mass balance between air and water stream describing thus, the rate of change of air temperature, humidity ratio, water temperature and evaporated water mass along tower height. The reliability of model predictions was ensured by comparisons made with pertinent experimental data, which were obtained from the literature. The paper elaborated the effect of atmospheric conditions, water mass flow rate and water inlet temperature on the variation of the thermodynamic properties of moist air inside the cooling tower and on its thermal performance characteristics. The analysis of the theoretical results revealed that the thermal performance of the cooling tower is sensitive to the degree of saturation of inlet air. Hence, the cooling capacity of the cooling tower increases with decreasing inlet air wet bulb temperature whereas the overall water temperature fall is curtailed with increasing water to air mass ratio. The change of inlet water temperature does not affect seriously the thermal behaviour of the cooling tower.
Analysis of windbreaker combinations on steam power plant natural draft dry cooling towers
• Effects of wind on the thermo-flow characteristics of cooling towers have been revealed. • Windbreaker types have been studied to decrease the negative effects of wind. • Results show that it is possible to use the momentum effect of wind. • Movable windbreakers should be used to change the direction according to the wind. A B S T R A C T Performance of natural draft dry cooling towers is significantly affected when the wind velocity is higher than a critical level according to their design and geometry. During this type of conditions, global electricity generation of power plants using especially dry type cooling towers is substantially reduced, up to as high as 40%. In order to decrease the reduction in electricity generation of power plants, it is possible to study on the dimensions of the cooling towers. Additionally, using different types of windbreakers can reduce the effects of unfavorable operating conditions. However, the direction of the wind changes with the seasons although the prevailing wind direction is nearly the same. In this study, internal flat and combination of internal flat–external rounded windbreakers have been analyzed by using the computational fluid dynamics approach. The combination of windbreakers, which is able to move axially around the cooling tower, has been propounded to arrange the flow characteristics during the windy days. The studies on the windbreakers in the literature have been aimed to decrease the negative effects of the wind; however, the design in this study provides also an increase in the air mass flowrate due to the momentum effect of the wind.