Unit Thermal Performance of Atmospheric Spray Cooling Systems

1980 ◽  
Vol 102 (2) ◽  
pp. 210-214 ◽  
Author(s):  
R. W. Porter ◽  
M. Jain ◽  
S. K. Chaturvedi
Keyword(s):  
Thermal Performance ◽  
Large Scale ◽  
Field Experiments ◽  
Characteristic Length ◽  
Local Heating ◽  
Spray Cooling ◽  
Sauter Mean Diameter ◽  
Cooling Systems ◽  
Group Number ◽  
Good Agreement

Thermal performance of an open atmospheric spray pond or canal depends on the direct-contact evaporative cooling of an individual spray unit (spray nozzle or module) and the interference caused by local heating and humidification. Droplet parameters may be combined into a dimensionless group, number of transfer units (NTU) or equivalent, whereas large-scale air-vapor dynamics determine interference through the local wet-bulb temperature. Quantity NTU were implied from field experiments for a floating module used in steam-condenser spray canals. Previous data were available for a fixed-pipe nozzle assembly used in spray ponds. Quantity NTU were also predicted using the Ranz-Marshall correlations with the Sauter-mean diameter used as the characteristic length. Good agreement with experiments was shown for diameters of 1–1.1 cm (module) and 1.9 mm (fixed-pipe nozzle).

Thermal Performance of Spray-Canal Cooling Systems

1980 ◽  
Vol 102 (4) ◽  
pp. 776-781
Author(s):  
S. K. Chaturvedi ◽  
R. W. Porter
Keyword(s):  
Power Plants ◽  
Field Experiments ◽  
Spray Cooling ◽  
Performance Model ◽  
Rational Analysis ◽  
Cooling Systems ◽  
Electric Power Plants ◽  
Power Stations ◽  
Dimensionless Groups ◽  
Race Track

Spray canals are alternatives to cooling ponds and towers for steam-electric power plants. The literature of thermal modeling is reviewed. A rational analysis supported by field experiments at two large central power stations has led to correlation of local spray cooling performance in terms of two dimensionless groups, one of which is dependent mainly on the type of spray module, and the other is a heating-humidification interference-allowance parameter which depends on wind speed and direction and the type and placement of modules. The analysis is incorporated into a systems performance model for arbitrary canal layout. Examples presented are the circular, race-track and straight double-back canals. Implications for design are discussed.

Mathematical Model for Spray Cooling Systems

1977 ◽  
Vol 99 (2) ◽  
pp. 279-283 ◽  
Author(s):  
H. A. Frediani ◽  
N. Smith
Keyword(s):  
Mathematical Model ◽  
Large Scale ◽  
Cooling System ◽  
Spray Cooling ◽  
System Model ◽  
Cellular Model ◽  
Cooling Systems ◽  
Cellular Analysis ◽  
Finite Difference Solution ◽  
Energy Equations

A mathematical model of a large-scale spray cooling system is described. The continuity and energy equations are developed for a cellular model representing a single spray in a system of sprays. The equations are solved using a finite-difference solution along a drop trajectory for both water and air parameters. The results of the cellular analysis are incorporated into a system model in which the interaction between sprays for both the water and air is considered. The model was used to simulate existing systems employing multiple rows of sprays, and the results of the calculations compare well with the available data.

Air-Vapor Dynamics in Large-Scale Atmospheric Spray Cooling Systems

1978 ◽  
Vol 100 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Sushil Chaturvedi ◽  
R. W. Porter
Keyword(s):  
Reasonable Agreement ◽  
Large Scale ◽  
Spray Cooling ◽  
Cooling Towers ◽  
Cooling Systems ◽  
Flow Through ◽  
Spray Field ◽  
Large Flow ◽  
Essential Problem ◽  
Theory And Experiments

Atmospheric spray cooling systems are alternatives to cooling towers and cooling ponds. A quantity NTU containing the spray drop-wise parameters allows prediction of cooling range if local wet-bulb temperature is known. The essential problem is predicting local wet-bulb proceeding windward through the spray field. Theory was developed for this purpose involving wind attenuation and turbulent diffusion. Experiments were performed on a large flow-through spray canal involving segments with two types of floating spray modules. Previous experimental data are available for a fixed manifolded spray pond. A comparison of theory and experiments shows reasonable agreement.

Thermal Performance of Spray Cooling Ponds at Zero Wind Velocity

1987 ◽  
Vol 109 (1) ◽  
pp. 212-217
Author(s):  
N. Moussiopoulos ◽  
G. Ernst
Keyword(s):  
Water Vapor ◽  
Numerical Solution ◽  
Wind Velocity ◽  
Air Temperature ◽  
Thermal Performance ◽  
Present Model ◽  
Spray Cooling ◽  
Vapor Transfer ◽  
Water Vapor Transfer ◽  
Good Agreement

The present model allows predictions of the thermal performance of spray cooling ponds in the case of zero wind velocity. Droplet cooling is described by modeling of the heat and water vapor transfer to the air. Temperature and humidity of air are obtained by the numerical solution of transport differential equations. Detailed results are presented and discussed. Predictions are in good agreement with the observed thermal performance of spray cooling ponds. Results are utilized for a check of assumptions made by NTU models.

Spray Cooling for Time Resolved Emission Measurements of ICs

2004 ◽  
Author(s):  
Rama R. Goruganthu ◽  
David Bethke ◽  
Shawn McBride ◽  
Tom Crawford ◽  
Jonathan Frank ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Performance ◽  
Flip Chip ◽  
Cooling System ◽  
Spray Cooling ◽  
Junction Temperature ◽  
Maximum Temperature ◽  
Uniform Heat Flux ◽  
High Heat Flux ◽  
Time Resolved

Abstract Spray cooling is implemented on an engineering tool for Time Resolved Emission measurements using a silicon solid immersion lens to achieve high spatial resolution and for probing high heat flux devices. Thermal performance is characterized using a thermal test vehicle consisting of a 4x3 array of cells each with a heater element and a thermal diode to monitor the temperature within the cell. The flip-chip packaged TTV is operated to achieve uniform heat flux across the die. The temperature distribution across the die is measured on the 4x3 grid of the die for various heat loads up to 180 W with corresponding heat flux of 204 W/cm2. Using water as coolant the maximum temperature differential across the die was about 30 °C while keeping the maximum junction temperature below 95 °C and at a heat flux of 200 W/cm2. Details of the thermal performance of spray cooling system as a function of flow rate, coolant

Thermal Performance Analysis of a Rectangular Longitudinal Finned Solar Air Heater With Semicircular Absorber Plate

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Satyender Singh ◽  
Prashant Dhiman
Keyword(s):  
Thermal Performance ◽  
Numerical Solutions ◽  
Solar Air Heater ◽  
Duct Flow ◽  
Balance Equations ◽  
Absorber Plate ◽  
Ansys Fluent ◽  
Air Heater ◽  
Glass Cover ◽  
Good Agreement

Thermal performance of a single-pass single-glass cover solar air heater consisting of semicircular absorber plate finned with rectangular longitudinal fins is investigated. The analysis is carried out for different hydraulic diameters, which were obtained by varying the diameter of the duct from 0.3–0.5 m. One to five numbers of fins are considered. Reynolds number ranges from 1600–4300. Analytical solutions for energy balance equations of different elements and duct flow of the solar air heater are presented; results are compared with finite-volume methodology based numerical solutions obtained from ansys fluent commercial software, and a fairly good agreement is achieved. Moreover, analysis is extended to check the effect of double-glass cover and the recycle of the exiting air. Results revealed that the use of double-glass cover and recycle operation improves the thermal performance of solar air heater.

scholarly journals Large-scale transcriptomics to dissect 2 years of the life of a fungal phytopathogen interacting with its host plant

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Elise J. Gay ◽  
Jessica L. Soyer ◽  
Nicolas Lapalu ◽  
Juliette Linglin ◽  
Isabelle Fudal ◽  
...  
Keyword(s):  
Host Plant ◽  
Large Scale ◽  
Field Experiments ◽  
Plant Residues ◽  
Plant Infection ◽  
Effector Genes ◽  
Controlled Conditions ◽  
Niche Adaptation ◽  
Depth Analysis ◽  
Fungal Genes

Abstract Background The fungus Leptosphaeria maculans has an exceptionally long and complex relationship with its host plant, Brassica napus, during which it switches between different lifestyles, including asymptomatic, biotrophic, necrotrophic, and saprotrophic stages. The fungus is also exemplary of “two-speed” genome organisms in the genome of which gene-rich and repeat-rich regions alternate. Except for a few stages of plant infection under controlled conditions, nothing is known about the genes mobilized by the fungus throughout its life cycle, which may last several years in the field. Results We performed RNA-seq on samples corresponding to all stages of the interaction of L. maculans with its host plant, either alive or dead (stem residues after harvest) in controlled conditions or in field experiments under natural inoculum pressure, over periods of time ranging from a few days to months or years. A total of 102 biological samples corresponding to 37 sets of conditions were analyzed. We show here that about 9% of the genes of this fungus are highly expressed during its interactions with its host plant. These genes are distributed into eight well-defined expression clusters, corresponding to specific infection lifestyles or to tissue-specific genes. All expression clusters are enriched in effector genes, and one cluster is specific to the saprophytic lifestyle on plant residues. One cluster, including genes known to be involved in the first phase of asymptomatic fungal growth in leaves, is re-used at each asymptomatic growth stage, regardless of the type of organ infected. The expression of the genes of this cluster is repeatedly turned on and off during infection. Whatever their expression profile, the genes of these clusters are enriched in heterochromatin regions associated with H3K9me3 or H3K27me3 repressive marks. These findings provide support for the hypothesis that part of the fungal genes involved in niche adaptation is located in heterochromatic regions of the genome, conferring an extreme plasticity of expression. Conclusion This work opens up new avenues for plant disease control, by identifying stage-specific effectors that could be used as targets for the identification of novel durable disease resistance genes, or for the in-depth analysis of chromatin remodeling during plant infection, which could be manipulated to interfere with the global expression of effector genes at crucial stages of plant infection.

scholarly journals EZ-ALBI Score for Predicting Hepatocellular Carcinoma Prognosis

Liver Cancer ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 734-743
Author(s):  
Kazuya Kariyama ◽  
Kazuhiro Nouso ◽  
Atsushi Hiraoka ◽  
Akiko Wakuta ◽  
Ayano Oonishi ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Liver Function ◽  
Large Scale ◽  
Regression Coefficient ◽  
Information Criterion ◽  
Proportional Hazard ◽  
Cox Proportional Hazard ◽  
Highly Correlated ◽  
Survival Risk ◽  
Good Agreement

<b><i>Introduction:</i></b> The ALBI score is acknowledged as the gold standard for the assessment of liver function in patients with hepatocellular carcinoma (HCC). Unlike the Child-Pugh score, the ALBI score uses only objective parameters, albumin (Alb) and total bilirubin (T.Bil), enabling a better evaluation. However, the complex calculation of the ALBI score limits its applicability. Therefore, we developed a simplified ALBI score, based on data from a large-scale HCC database.We used the data of 5,249 naïve HCC cases registered in eight collaborating hospitals. <b><i>Methods:</i></b> We developed a new score, the EZ (Easy)-ALBI score, based on regression coefficients of Alb and T.Bil for survival risk in a multivariate Cox proportional hazard model. We also developed the EZ-ALBI grade and EZ-ALBI-T grade as alternative options for the ALBI grade and ALBI-T grade and evaluated their stratifying ability. <b><i>Results:</i></b> The equation used to calculate the EZ-ALBI score was simple {[T.Bil (mg/dL)] – [9 × Alb (g/dL)]}; this value highly correlated with the ALBI score (correlation coefficient, 0.981; <i>p</i> &#x3c; 0.0001). The correlation was preserved across different Barcelona clinic liver cancer grade scores (regression coefficient, 0.93–0.98) and across different hospitals (regression coefficient, 0.98–0.99), indicating good generalizability. Although a good agreement was observed between ALBI and EZ-ALBI, discrepancies were observed in patients with poor liver function (T.Bil, ≥3 mg/dL; regression coefficient, 0.877). The stratifying ability of EZ-ALBI grade and EZ-ALBI-T grade were good and their Akaike’s information criterion values (35,897 and 34,812, respectively) were comparable with those of ALBI grade and ALBI-T grade (35,914 and 34,816, respectively). <b><i>Conclusions:</i></b> The EZ-ALBI score, EZ-ALBI grade, and EZ-ALBI-T grade are useful, simple scores, which might replace the conventional ALBI score in the future.

Thermal performance comparison of different sun tracking configurations

2019 ◽  
Vol 88 (2) ◽  
pp. 20902
Author(s):  
O. Achkari ◽  
A. El Fadar
Keyword(s):  
Thermal Performance ◽  
Electricity Generation ◽  
Arid Regions ◽  
Performance Comparison ◽  
Water Desalination ◽  
Parabolic Trough ◽  
Parabolic Trough Collector ◽  
The Impact ◽  
The Mathematical Model ◽  
Good Agreement

Parabolic trough collector (PTC) is one of the most widespread solar concentration technologies and represents the biggest share of the CSP market; it is currently used in various applications, such as electricity generation, heat production for industrial processes, water desalination in arid regions and industrial cooling. The current paper provides a synopsis of the commonly used sun trackers and investigates the impact of various sun tracking modes on thermal performance of a parabolic trough collector. Two sun-tracking configurations, full automatic and semi-automatic, and a stationary one have numerically been investigated. The simulation results have shown that, under the system conditions (design, operating and weather), the PTC's performance depends strongly on the kind of sun tracking technique and on how this technique is exploited. Furthermore, the current study has proven that there are some optimal semi-automatic configurations that are more efficient than one-axis sun tracking systems. The comparison of the mathematical model used in this paper with the thermal profile of some experimental data available in the literature has shown a good agreement with a remarkably low relative error (2.93%).

Development and Testing of an Unmanned Aerial Vehicle for Large Scale Particle Image Velocimetry

2014 ◽  
Author(s):  
Christopher Pagano ◽  
Flavia Tauro ◽  
Salvatore Grimaldi ◽  
Maurizio Porfiri
Keyword(s):  
Particle Image Velocimetry ◽  
Large Scale ◽  
Field Experiments ◽  
Particle Image ◽  
Low Cost ◽  
Surface Flow ◽  
Natural Environments ◽  
Natural Stream ◽  
Image Velocimetry ◽  
Scale Particle

Large scale particle image velocimetry (LSPIV) is a nonintrusive environmental monitoring methodology that allows for continuous characterization of surface flows in natural catchments. Despite its promise, the implementation of LSPIV in natural environments is limited to areas accessible to human operators. In this work, we propose a novel experimental configuration that allows for unsupervised LSPIV over large water bodies. Specifically, we design, develop, and characterize a lightweight, low cost, and stable quadricopter hosting a digital acquisition system. An active gimbal maintains the camera lens orthogonal to the water surface, thus preventing severe image distortions. Field experiments are performed to characterize the vehicle and assess the feasibility of the approach. We demonstrate that the quadricopter can hover above an area of 1×1m2 for 4–5 minutes with a payload of 500g. Further, LSPIV measurements on a natural stream confirm that the methodology can be reliably used for surface flow studies.

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