Effects of inlet relative humidity and inlet temperature on the performance of counterflow wet cooling tower based on exergy analysis

2008 ◽  
Vol 49 (10) ◽  
pp. 2795-2800 ◽  
Author(s):  
Thirapong Muangnoi ◽  
Wanchai Asvapoositkul ◽  
Somchai Wongwises
Keyword(s):  
Relative Humidity ◽  
Exergy Analysis ◽  
Cooling Tower ◽  
Inlet Temperature

scholarly journals PERFORMANCE ANALYSIS OF ALTERNATIVE COVERINGS FOR COOLING TOWERS IN BRAZILIAN CAPITALS THROUGH NUMERICAL MODELING

2017 ◽  
Vol 16 (2) ◽  
pp. 67
Author(s):  
A. C. C. Tomás ◽  
P. H. Souza ◽  
A. R. M. Primo
Keyword(s):  
Relative Humidity ◽  
Cooling Tower ◽  
Waste Heat ◽  
Heat Removal ◽  
Poor Performance ◽  
Climatic Conditions ◽  
Capital City ◽  
Inlet Temperature ◽  
Cooling Towers ◽  
Climate Conditions

A cooling tower is a heat removal device used to transfer waste heat to the atmosphere process. Today, commercial cooling towers use plastic coverings, specially developed for this application. It is known that alternative coverings have been an increasingly viable solution thanks to its performance and cost. The purpose of this study was to evaluate, through numerical simulation, the performance of different alternative coverings under different climatic conditions. Therefore, we used, as reference, the climate of the state capitals and their respective geographic regions. The performance of these coverings was evaluated through observation of three parameters: effectiveness, approach and cooling. The main input data used by the software EES (Engineering Equation Solver) for the calculation of evaluation parameters were: experimental NUT of each covering, average local temperature, local air pressure and relative humidity. The flow of water and air were set at 0.33 L / s and 170 L / s, respectively. We concluded that the air inlet temperature and relative humidity at each location greatly influence the performance of the coverings. The alternative covering that showed the best results was the "cross-fiber and neck", with an efficiency about 35% lower than the industrial covering. The Brazilian capital city with the best performances for alternative coverings was Palmas (TO). This is due to the very low relative humidity found in the city in the summer. Air humidity is also responsible for the poor performance of coverings in the capitals of the North. In general, the region with the best performance was the South, due to the characteristics of the sub-tropical climate. Regions that had the worst results were North / Northeast because of the weather that combines high temperatures with high / moderate humidity, respectively. Thus, the study of climate conditions is indispensable for the operation prevision of a cooling tower. Alternative coverings will be viable depending on the location.

scholarly journals ANALYSIS OF HEAT AND MASS TRANSFER ON COOLING TOWER FILL

2020 ◽  
Vol 14 (1) ◽  
pp. 25
Author(s):  
Abdul Aziz Rohman Hakim ◽  
Engkos Achmad Kosasih
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Relative Humidity ◽  
Heat And Mass Transfer ◽  
Cooling Tower ◽  
Stream Velocity ◽  
Design Data ◽  
Analogy Method ◽  
Ambient Relative Humidity ◽  
Air Stream

This paper discusses heat and mass transfer in cooling tower fill. In this research, dry bulb temperature at the bottom fill, ambient relative humidity, air stream velocity entering fill, dry bulb temperature leaving the fill, relative humidity of air leaving the fill, inlet and outlet water temperature of cooling tower were measured. Those data used in heat and mass transfer calculation in cooling tower fill. Then, do the heat and mass transfer calculation based on proposed approch. The results are compared with design data. The design and analogy method showed different  result. The parameter which influence the heat transfer at cooling tower are represented by coefficient of heat transfer hl and coefficient of mass transfer k­l. The differencies result between design and analogy method shows that there is important parameter which different. Deeply study needed for it.

scholarly journals Numerical Analysis of Laminar Convective Condensation with the Presence of Noncondensable Gas Flowing Downward in a Vertical Channel

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Mustapha Ait Hssain ◽  
Youness El Hammami ◽  
Rachid Mir ◽  
Sara Armou ◽  
Kaoutar Zine-Dine
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Relative Humidity ◽  
Liquid Film ◽  
Vertical Channel ◽  
Dimensionless Temperature ◽  
Condensation Process ◽  
Inlet Temperature ◽  
Mixture Flow ◽  
Noncondensable Gas

The purpose of this paper is to study and perform a numerical analysis of the simultaneous processes of mass and heat transfer during the condensation process of a steam in the existence of noncondensable gas (NCG) inside a descending vertical channel. In this study, the flow of the vapor-air mixture is laminar and the saturation conditions are prevailing at the inlet of the channel. The coupled control equations for liquid film, interfacial conditions, and mixture flow are solved together using the approach of finite volume. Detailed and valuable results are presented both in the liquid condensate film and in the mixing regions. These detailed results contain the dimensionless velocity and dimensionless temperature profiles in both phases, the dimensionless mass fraction of vapor, the axial variation of the dimensionless thickness of the film liquid δ⁎, and the accumulated condensate rate Mr as well the local Nusselt number Nuy. The relative humidity at the inlet varies from 60% to 100% and the inlet temperature from 40°C to 80°C. The results confirm that a decrease in the mass concentration of NCG by the increasing the inlet relative humidity has a direct influence on the liquid film layer, the local number of Nusselt, and the variation of condensation rate accumulated through the channel. The results also designate that an increase of the inlet relative humidity and the inlet temperature ameliorates the condensation process. The comparison made for the coefficient of heat transfer due to condensation process and the condensate liquid film thickness with the literature results is in good concordance which gives more credibility to our calculation model.

Overall Optimization and Exergy Analysis of an Air Conditioning System Using a Series-Series Counterflow Arrangement of Water Chillers

2019 ◽  
Vol 27 (04) ◽  
pp. 1950034 ◽  
Author(s):  
Nguyen Minh Phu
Keyword(s):  
Air Conditioning ◽  
Exergy Analysis ◽  
Cooling Tower ◽  
Exergy Efficiency ◽  
Air Conditioning System ◽  
In Series ◽  
Main Components ◽  
Compressor Power ◽  
Cooling Coil ◽  
Optimal Set

When water chillers are arranged in series-series counterflow (SSCF), the compressor lift of each chiller is decreased in comparison with that of water chillers in parallel. This means that the compressor power of SSCF chillers is lower than that of parallel chillers. In this paper, models of the main components in an air conditioning system were developed and verified to predict the behaviors of the whole system with respect to SSCF chillers. The results showed that performance was maximized with three SSCF chillers when the system was operated with normal set points. The performance was further improved to 26% and decreased with the number of SSCF chillers when the system was operated with optimal set points. The SSCF chiller system also demonstrated higher exergy efficiency regardless of the number of SSCF chillers. The irreversibility of components in SSCF chillers was rather low. However, the irreversibility of the cooling tower and cooling coil was slightly higher and lower, respectively, than those in the parallel chiller system.

Performance analysis of an air humidifier integrated gas turbine with film air cooling of turbine blade

2013 ◽  
Vol 24 (4) ◽  
pp. 71-81 ◽  
Author(s):  
Alok K. Mahapatra ◽  
Sanjay Sanjay
Keyword(s):  
Relative Humidity ◽  
Ambient Temperature ◽  
Pressure Ratio ◽  
Temperature Drop ◽  
Inlet Temperature ◽  
Specific Work ◽  
Blade Cooling ◽  
Ambient Relative Humidity ◽  
Turbine Inlet ◽  
Compressor Pressure Ratio

A computational analysis to investigate the effects of compressor pressure ratio, turbine inlet temperature, ambient relative humidity and ambient temperature on the performance parameters of an air cooled gas turbine cycle with evaporative cooling of inlet air has been presented. The blade cooling method selected is film cooling. The analysis indicates that the mass of coolant required for blade cooling is reduced with increase in temperature drop across the humidifier. Both decrease in ambient temperature and ambient relative humidity results in an increase in plant efficiency and plant specific work. The highest efficiency is obtained at a turbine inlet temperature of 1500 K for all range of ambient relative humidity and ambient temperature, beyond which it decreases. The compressor pressure ratio corresponding to the maximum plant specific work, however, varies with both ambient relative humidity and ambient temperature. The increase in specific work due to drop in ambient relative humidity is more pronounced at higher pressure ratios. Similarly, the increase in efficiency due to ambient temperature drop is prominent at higher turbine inlet temperatures. Finally, a design nomograph is presented to select the design parameters corresponding to best efficiency and specific work.

Impact of Relative Humidity on Cooling Tower Plume Dispersion

2013 ◽  
Vol 807-809 ◽  
pp. 168-171
Author(s):  
Rui Ping Guo ◽  
Chun Lin Yang ◽  
Chun Ming Zhang ◽  
Bing Lan
Keyword(s):  
Relative Humidity ◽  
Environmental Impact ◽  
Impact Assessment ◽  
Wind Direction ◽  
Cooling Tower ◽  
Plume Dispersion ◽  
Plume Height ◽  
Different Seasons ◽  
Change Trend ◽  
Dispersion Character

The SACTI model (Seasonal Annual Cooling Tower Impact) as the environmental impact assessment of cooling tower was applied in this paper, which was used to simulate the plume characters under different kinds of relative humidity. The three kinds of relative humidity were 70%, 80% and 90% and it was analyzed that the plume character under these three kinds of relative humidity. Results showed that the plume length, plume height and plume radius will present different change trend when relative humidity changed. Additionally, the plume dispersion character in different seasons presented obviously variations and the different wind direction also play important role in prediction of cooling tower plume dispersion.

The Impact of Atmospheric Conditions on Gas Turbine Performance

1990 ◽  
Vol 112 (4) ◽  
pp. 590-596 ◽  
Author(s):  
A. A. El Hadik
Keyword(s):  
Relative Humidity ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Arabian Gulf ◽  
Inlet Temperature ◽  
Atmospheric Conditions ◽  
Design Factor ◽  
Turbine Performance ◽  
The Impact

In a hot summer climate, as in Kuwait and other Arabian Gulf countries, the performance of a gas turbine deteriorates drastically during the high-temperature hours (up to 60°C in Kuwait). Power demand is the highest at these times. This necessitates an increase in installed gas turbine capacities to balance this deterioration. Gas turbines users are becoming aware of this problem as they depend more on gas turbines to satisfy their power needs and process heat for desalination due to the recent technical and economical development of gas turbines. This paper is devoted to studying the impact of atmospheric conditions, such as ambient temperature, pressure, and relative humidity on gas turbine performance. The reason for considering air pressures different from standard atmospheric pressure at the compressor inlet is the variation of this pressure with altitude. The results of this study can be generalized to include the cases of flights at high altitudes. A fully interactive computer program based on the derived governing equations is developed. The effects of typical variations of atmospheric conditions on power output and efficiency are considered. These include ambient temperature (range from −20 to 60°C), altitude (range from zero to 2000 m above sea level), and relative humidity (range from zero to 100 percent). The thermal efficiency and specific net work of a gas turbine were calculated at different values of maximum turbine inlet temperature (TIT) and variable environmental conditions. The value of TIT is a design factor that depends on the material specifications and the fuel/air ratio. Typical operating values of TIT in modern gas turbines were chosen for this study: 1000, 1200, 1400, and 1600 K. Both partial and full loads were considered in the analysis. Finally the calculated results were compared with actual gas turbine data supplied by manufacturers.

scholarly journals Exergy Analysis of Modified Solar Still

2015 ◽  
Vol 10 (2) ◽  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Brackish Water ◽  
Solar Collector ◽  
Exergy Analysis ◽  
Cooling Tower ◽  
Volume Flow Rate ◽  
Exergy Efficiency ◽  
Solar Still

A new design of solar still consist of flat plate solar collector, heat exchanger and cooling tower, was built and tested under Iraq weather at March. The still was tested under different mass flow rate of brackish water entering the flate plate solar collector, ranging from 0.01 to 0.015 kg/s. The volume flow rate of air through cooling tower was 0.0195 m3 /s. A full details of overall system as well as for system components exergy analysis were achieved. It was found that the maximum daily exergy efficiency of the still is less than 1%. While the maximum hourly exergy efficiency and maximum productivity for such combination were 3.46 kg/day and 1.6% , respectively, when the mass flow rate of brackish water was 0.013 kg/s.

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