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.

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.

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).

The Role of Free-Living Amoebae Occurring in Heated Effluents as Causative Agents of Human Disease

1983 ◽  
Vol 15 (10) ◽  
pp. 135-147
Author(s):  
Maurice A Shapiro ◽  
Meryl H Karol ◽  
Georg Keleti ◽  
Jan L Sykora ◽  
A J Martinez
Keyword(s):  
Human Disease ◽  
Power Plants ◽  
Elevated Temperatures ◽  
Human Subjects ◽  
Cooling Towers ◽  
Free Living ◽  
Cooling Systems ◽  
Delayed Onset ◽  
Source Of Infection ◽  
Causative Agents

It has been shown that several pathogenic organisms may be frequently found in thermal effluents and cooling systems of coal fired power plants. One of them is pathogenic Naegleria fowleri, the causative agent of an acute fatal human disease - primary amoebic meningoencephalitis (PAM). In our study two out of eight power plants investigated, harbored pathogenic N. fowleri in heated water or cooling towers. The occurrence of this organism was related to elevated temperatures. No significant correlation was found for other biological and chemical parameters. In addition, pathogenic Acanthamoeba which causes granulomatous amoebic encephalitis (GAE) was found in the tested heated effluents from coal fired power plants. Non-pathogenic strains of N. fowleri as well as other free-living and “harmless” amoebae were also very abundant in effluents from all investigated coal fired power plants and cooling towers. It has been reported that several species of nonpathogenic amoebae were isolated from humidifiers and air conditioning systems. Serological testing of symptomatic human subjects has indicated that these organisms may be one of the causative agents of hypersensitivity pneumonitis. An experimental study performed in our laboratory involved testing of guinea pigs sensitized by injection of axenic, non-pathogenic N. gruberi. Delayed onset skin reactivity was apparent in all animals injected with the antigen. Antibodies were detected in all sensitized animals. Bronchial provocation challenge employed to investigate pulmonary hypersensitivity was also used, and yielded positive results. All the sensitized animals displayed delayed onset respiratory responses. The results of this study indicate that not only pathogenic but also non-pathogenic free-living amoebae may be important causative agents of human disease. The occurrence of these organisms in cooling systems from coal fired power plants indicates that these facilities may be an important source of infection.

scholarly journals Applying Biomimetic Principles to Thermoelectric Cooling Devices for Water Collection

2017 ◽  
Vol 7 (3) ◽  
pp. 27
Author(s):  
Kyle B Davidson ◽  
Bahram Asiabanpour ◽  
Zaid Almusaied
Keyword(s):  
Large Scale ◽  
Cost Effective ◽  
Thermoelectric Cooling ◽  
Device Structure ◽  
Cooling Systems ◽  
Cooling Devices ◽  
Water Collection ◽  
Maximum Water ◽  
The Ideal

The shortage of freshwater resources in the world has developed the need for sustainable, cost-effective technologies that can produce freshwater on a large scale. Current solutions often have extensive manufacturing requirements, or involve the use of large quantities of energy or toxic chemicals. Atmospheric water generating solutions that minimize the depletion of natural resources can be achieved by incorporating biomimetics, a classification of design inspired by nature. This research seeks to optimize thermoelectric cooling systems for use in water harvesting applications by analyzing the different factors that affect surface temperature and water condensation in TEC devices. Further experiments will be directed towards developing a robust, repeatable system, as well as an accurate measurement system. Surface modifications, device structure and orientation, and power generation will also be studied to better understand the ideal conditions for maximum water collection in thermoelectric cooling systems.

scholarly journals Combined numerical and experimental study of microstructure and permeability in porous granular media

2020 ◽  
Author(s):  
Philipp Eichheimer ◽  
Marcel Thielmann ◽  
Wakana Fujita ◽  
Gregor J. Golabek ◽  
Michihiko Nakamura ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Numerical Simulations ◽  
Granular Media ◽  
Large Scale ◽  
Earth Science ◽  
Numerical Models ◽  
Effective Porosity ◽  
Flow Properties ◽  
Wide Range ◽  
Flow Through

Abstract. Fluid flow on different scales is of interest for several Earth science disciplines like petrophysics, hydrogeology and volcanology. To parameterize fluid flow in large-scale numerical simulations (e.g. groundwater and volcanic systems), flow properties on the microscale need to be considered. For this purpose experimental and numerical investigations of flow through porous media over a wide range of porosities are necessary. In the present study we sinter glass bead media with various porosities. The microstructure, namely effective porosity and effective specific surface, is investigated using image processing. We determine flow properties like hydraulic tortuosity and permeability using both experimental measurements and numerical simulations. By fitting microstructural and flow properties to porosity, we obtain a modified Kozeny-Carman equation for isotropic low-porosity media, that can be used to simulate permeability in large-scale numerical models. To verify the modified Kozeny-Carman equation we compare it to the computed and measured permeability values.

Short-term emersion affects cardiac function and regional haemolymph distribution in the crab Cancer magister

1996 ◽  
Vol 199 (3) ◽  
pp. 569-578
Author(s):  
C Airriess ◽  
B Mcmahon
Keyword(s):  
Stroke Volume ◽  
Cardiac Function ◽  
Large Scale ◽  
Time Course ◽  
Beat Frequency ◽  
Heart Beat ◽  
Experimental Chamber ◽  
Cancer Magister ◽  
Flow Through ◽  
Cardiac Stroke Volume

Changes in cardiac function and arterial haemolymph flow associated with 6 h of emersion were investigated in the crab Cancer magister using an ultrasonic flowmeter. This species is usually found sublittorally but, owing to the large-scale horizontal water movements associated with extreme tides, C. magister may occasionally become stranded on the beach. Laboratory experiments were designed such that the emersion period was typical of those that might be experienced by this crab in its natural environment. The frequency of the heart beat began to decline sharply almost immediately after the start of the experimental emersion period. Cardiac stroke volume fell more gradually. The combined reduction in these two variables led to a maximum decrease in cardiac output of more than 70 % from the control rate. Haemolymph flow through all the arteries originating at the heart, with the exception of the anterior aorta, also declined markedly during emersion. As the water level in the experimental chamber fell below the inhalant branchial openings, a stereotypical, dramatic increase in haemolymph flow through the anterior aorta began and this continued for the duration of the emersion period. The rapid time course of the decline in heart-beat frequency and the increase in haemolymph flow through the anterior aorta suggest a neural mechanism responding to the absence of ventilatory water in the branchial chambers. These responses may be adaptations, respectively, to conserve energy by reducing the minute volume of haemolymph pumped by the heart and to protect the supply of haemolymph to cephalic elements of the central nervous system. The decline in cardiac stroke volume, which occurs more slowly over the emersion period, may be a passive result of the failure to supply sufficient O2 to meet the aerobic demands of the cardiac ganglion.

Minimization of Energy Using Heuristic Resource Allocation and Migration for Cloud Computing

2021 ◽  
Vol 12 (1) ◽  
pp. 74-83
Author(s):  
Manjunatha S. ◽  
Suresh L.
Keyword(s):  
Cloud Computing ◽  
Data Center ◽  
Large Scale ◽  
Data Centers ◽  
Service Providers ◽  
Cost Effective ◽  
Cooling Systems ◽  
Operational Costs ◽  
Cloud Computing Service ◽  
And Migration

Data center is a cost-effective infrastructure for storing large volumes of data and hosting large-scale service applications. Cloud computing service providers are rapidly deploying data centers across the world with a huge number of servers and switches. These data centers consume significant amounts of energy, contributing to high operational costs. Thus, optimizing the energy consumption of servers and networks in data centers can reduce operational costs. In a data center, power consumption is mainly due to servers, networking devices, and cooling systems, and an effective energy-saving strategy is to consolidate the computation and communication into a smaller number of servers and network devices and then power off as many unneeded servers and network devices as possible.

Sign in / Sign up

Export Citation Format

Share Document