Air cooling by evaporating droplets in the upward flow of a condenser

Tissot, Julien; Boulet, Pascal; Trinquet, F.; Fournaison, Laurence; Macchi-Tejeda, Hélène

doi:10.1016/j.ijthermalsci.2011.06.004

Cited by 72 publications

(58 citation statements)

References 16 publications

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“…Furthermore, lower air velocity means larger coverage area because the time for droplets to lose momentum and follow the air stream is longer, which results in a better coverage area. These trends are in agreement with previous studies [20,43].…”

Section: Effect Of Air Velocity On Spray Cooling Performancesupporting

confidence: 94%

“…At 3 m/s, the effect of droplet size on evaporation is balanced by the effect of penetration on evaporation. This conclusion is in agreement with Tissot [43] findings which had higher evaporation at larger droplet diameter under the same operational condition.…”

Section: Insight Into Spray Cooling Processsupporting

confidence: 93%

“…The spray cooling performance is evaluated based on the outlet air temperature measurements carried out at a distance of 4.7 downstream of the nozzle (Table 5- outcome is in agreement with Tissot et al study [43] which found that spray dispersion (area coverage of the spray) is an important parameter affecting spray cooling efficiency as well as evaporation rate due to the momentum exchange between the air stream and droplets. To provide a better insight into the relationship between cooling efficiency and droplet size, a dispersion factor, defined as the ratio of the actual coverage area to the total area is introduced and referred as "coverage area ratio".…”

Section: Spray Cooling Performancesupporting

confidence: 78%

“…A numerical investigation on evaporating sprayed airflow was conducted by Tissot et al [43] A recent parametric study conducted by Montazeri et al [45] using three-dimensional CFD simulation to investigate the influence of different spray characteristics parameters on spray cooling performance under different inlet air conditions. The effect of droplet size distribution, droplet temperature, air temperature, air humidity and air velocity on spray cooling performance was investigated.…”

Section: Air Conditioning and Refrigerationmentioning

confidence: 99%

“…Spray cooling performance is also strongly influenced by air velocity [20,40,45]. Some of the other important parameters are: (a) nozzle cone angle, (b) water injection rate, (c) droplet velocity at nozzle exit, (d) injection direction, and (e) meteorological condition [19,26,40,43,45].…”

Section: Paper Content 1 Introductionmentioning

confidence: 99%

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Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

Alkhedhair¹

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Geothermal energy is a promising renewable energy to be used for baseload electricity. Most potential sites with high geothermal temperature are mostly located in remote areas where water is limited. This is besides water scarcity and environmental protection, which made dry cooling systems a better alternative solution for heat rejection of power plants. Furthermore, natural draft cooling towers have the advantage of avoiding parasitic losses introduced by the fans at mechanical draft cooling towers. However, power plants utilizing dry cooling technologies experience a significant reduction in power generation during high ambient temperature periods. This reduction often goes along with the peak power demand which results in a great loss for the power plant owners. In certain instances, dry cooling tower performance can be enhanced during these periods by pre cooling of the inlet air by spraying atomized water into the inlet air.The present study introduces the use of spray cooling for inlet air pre-cooling in natural draft cooling towers. Spray cooling is investigated in this study due to its simplicity, low capital cost, ease of operation and maintenance, and capability of increasing power plant efficiency while consuming only a small amount of water compared to wet cooling towers or other evaporative cooling methods. Although spray cooling has found successful applications in process coolers and gas turbine inlet air cooling, the large scale applications in power industry have been limited.Several issues limit the application in power industry. The main one is the incomplete evaporation of water droplets which can cause corrosion and scaling of heat exchanger surface. Incomplete evaporation also increases operational cost due to water consumption. To the best of our knowledge, a detailed investigation of the spray cooling performance in natural draft dry cooling towers operating environment has not yet been performed. The aim of the current work is to optimise a spray cooling system for inlet air pre-cooling in natural draft dry cooling towers.In the present study, an Eulerian-Lagrangian 3-D numerical model was developed which is capable of simulating evaporating water sprays produced by real nozzles. In order to reproduce real nozzle characteristics in the simulation, a new adaptable method for hollow-cone spray representation in Eulerian-Lagrangian numerical models was developed. This allows real nozzles characterised during experiments to be included in the simulation, thereby correctly accounting for radial evolution of droplet size distribution and air/droplets momentum exchange. The CFD model was applied to calculate local droplet transport and evaporation, and spray cooling efficiency at different operating conditions for spray cooling systems optimisation under typical Natural Draft Dry Cooling Tower conditions.iii Experimental measurements from a wind tunnel test rig simulating Natural Draft Dry Cooling Tower inlet flow conditions have been performed in order to investigate droplet transport...

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Section: Effect Of Air Velocity On Spray Cooling Performancesupporting

confidence: 94%

Section: Insight Into Spray Cooling Processsupporting

confidence: 93%

Section: Spray Cooling Performancesupporting

confidence: 78%

Section: Air Conditioning and Refrigerationmentioning

confidence: 99%

Section: Paper Content 1 Introductionmentioning

confidence: 99%

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Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

Alkhedhair¹

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Analysis of the performance of direct contact heat exchange systems for application in mine waste heat recovery

Kalantari

Amiri

Ghoreishi‐Madiseh

2021

Intl J of Energy Research

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Due to their relatively high thermal effectiveness and ease-of-use, direct contact heat exchange units are a favorable choice in heat recovery applications. Today, spray-based direct heat exchangers are commonly used for a variety of applications, including evaporative cooling and heat recovery. Yet in spite of their versatility, these heat exchangers are not well-understood, mainly due to their complex liquid/gas interactions, which may deem poorly-designed systems as undesirable and infeasible. Spray nozzle height and type (hollow and full cone), droplet diameter distribution, inlet air velocity and humidity, and water spray velocity are key parameters required to establish a clear understanding of direct heat exchange performance. To better understand such a multivariable phenomenon, this article offers a comprehensive study of the impact of these key factors. The main purpose of this study is to evaluate the validity of two different methods proposed for evaluating the performance of heat and mass transfer in large-scale direct contact heat exchangers, namely one-dimensional and threedimensional approaches. The results of the present study show that while the one-dimensional approach is able to capture the experimental data within 10% of agreement with experiment, the three-dimensional approach reduces this error to 5%. In addition, this study aims to provide a framework to conduct future parametric studies with the goal of highlighting key performance factors understanding of which are a necessity for improved design of direct contact heat exchangers used in mine waste heat recovery applications.

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Adiabatic Efficiency of Monoblock Air Supply Unit with Humidification Module Based on Porous Rotating Atomizers

Sibgatullin

Сафиуллин

2022

Lecture Notes in Civil Engineering

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Air cooling by evaporating droplets in the upward flow of a condenser

Cited by 72 publications

References 16 publications

Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

Analysis of the performance of direct contact heat exchange systems for application in mine waste heat recovery

Adiabatic Efficiency of Monoblock Air Supply Unit with Humidification Module Based on Porous Rotating Atomizers

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