Thermal behaviour of closed wet cooling towers for use with chilled ceilings (original) (raw)
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International Journal of Energy Research, 2000
A closed wet cooling tower, adapted for use with chilled ceilings in buildings, was tested experimentally. The thermal e$ciency of the cooling tower was measured for di!erent air #ow rates, water #ow rates, spray #ow rates and wet bulb air temperatures. CFD was also used to predict the thermal performance of the cooling tower. Good agreement was obtained between CFD prediction and experimental measurement.
Thermal performance analysis of a closed wet cooling tower
Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 2007
A detailed model was developed and employed to examine the thermal performance of a closed wet cooling tower. The model is capable of predicting the variation of air thermodynamic properties, sprayed and serpentine water temperature as well as heat transfer rates exchanged between air and falling water stream inside the indirect wet cooling tower. The reliability of simulations was tested against experimental data obtained from the literature. A parametric study was conducted to evaluate the thermal behaviour of the indirect cooling tower under various air mass flowrates, serpentine water mass flowrates and inlet temperatures. The results of the theoretical investigation revealed an increase in cooling capacity and percentage loss of sprayed water due to evaporation, with increasing air mass flowrate. On the other hand, the increase of serpentine water mass flowrate resulted in slight increase in the overall temperature reduction of serpentine water. The effect of variable serpentine water inlet temperature on thermal performance of the indirect wet cooling tower was insignificant compared to other cases. Thermal performance analysis of a closed wet cooling tower Proc. IMechE Vol. 221 Part E: J. Process Mechanical Engineering JPME119 © IMechE 2007 Thermal performance analysis of a closed wet cooling tower JPME119
Thermal performances investigation of a wet cooling tower
Applied Thermal Engineering, 2007
This paper presents an experimental investigation of the thermal performances of a forced draft counter flow wet cooling tower filled with an ''VGA'' (Vertical Grid Apparatus) type packing. The packing is 0.42 m high and consists of four (04) galvanised sheets having a zigzag form, between which are disposed three (03) metallic vertical grids in parallel with a cross sectional test area of 0.0222 m 2 (0.15 m · 0.148 m). This study investigates the effect of the air and water flow rates on the cooling water range as well as the tower characteristic, for different inlet water temperatures. Two operating regimes were observed during the air water contact, a pellicular regime (PR) and a bubble and dispersion regime (BDR). These two regimes can determine the best way to promote the heat transfer. The BDR regime seems to be more efficient than the pellicular regime, as it enables to cool larger water flow rates. The comparison between the obtained results and those found in the literature for other types of packing indicates that this type possesses very interesting thermal performances.
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.
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.
Studies on Thermal Performance Analysis on Cooling Towers -A Review
Journal of Advanced Mechanical Sciences, 2022
Cooling towers have been in use for different industrial applications for many years. These are a particular class of heat exchangers where industrial process water comes in contact with coolant air, enabling efficient heat rejection from circulating fluid-usually water. There have been many research attempts to improve the overall thermal performance of these systems to develop optimum working methodologies and address current systems' issues. This literature review is done to find out the various thermal performance analysis studies done on various industrial cooling towers.
Performance characteristics of counter flow wet cooling towers
Energy Conversion and Management, 2003
Cooling towers are one of the biggest heat and mass transfer devices that are in widespread use. In this paper, we use a detailed model of counter flow wet cooling towers in investigating the performance characteristics. The validity of the model is checked by experimental data reported in the literature. The thermal performance of the cooling towers is clearly explained in terms of varying air and water temperatures, as well as the driving potential for convection and evaporation heat transfer, along the height of the tower. The relative contribution of each mode of heat transfer rate to the total heat transfer rate in the cooling tower is established. It is demonstrated with an example problem that the predominant mode of heat transfer is evaporation. For example, evaporation contributes about 62.5% of the total rate of heat transfer at the bottom of the tower and almost 90% at the top of the tower. The variation of air and water temperatures along the height of the tower (process line) is explained on psychometric charts.
Effective Thermal Design Of Cooling Towers
Various misconceptions arise when it comes to the thermal design of cooling towers. Sometimes related parameters, such as range, approach, effectiveness, liquid-to-gas ratio ( L/G), wet-bulb temperature, cooling water temperature, relative humidity, number of transfer units (NTU) and other terms create a confusion for the designer in effectively sizing, selecting and evaluating a particular cooling tower. This leads to inadequate design.
Studies and Experimentation on Cooling Towers: A Review
2015
Cooling tower is one of the important utility in chemical industries. Normally they are used to dissipate heat from heat sources to heat sink. The cooling of hot effluent and process water is required from reuse and environmental point of view. Induced, forced and natural draft cooling towers are used according to the requirements in industries. Natural draft cooling towers use atmospheric air. In forced draft cooling air is forced into the tower using blower. In induced draft cooling towers, air is sucked from other end. The water cooling happens because of humidification of air. The heat lost by water is heat gained by air. Water recirculation is also important aspect in the cooling towers. The effectiveness of cooling tower depends on flow rates of air and water and water temperature. Minimization of heat loss is one of the important aspect of studies carried out by various investigators. The interfacial area between air and water is also crucial factor in cooling towers. Three types of packings used in cooling towers are film, splash and film-grid packings. Also it was observed that drift is one of the important losses in cooling towers. Various shapes of cooling towers are tried by various investigators to study effectiveness. Hyperbolic shape was advantageous due to higher area at bottom. It provides aerodynamics, strength, and stability. The present review is aimed at summarizing studies and research on cooling tower for increasing efficiency and power savings to make it more economical and efficient.