AN AIR-VAPOR-DROPLET LOCAL INTERACTION MODEL FOR SPRAY UNITS.
Item
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Title
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AN AIR-VAPOR-DROPLET LOCAL INTERACTION MODEL FOR SPRAY UNITS.
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Identifier
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AAI8023726
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identifier
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8023726
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Creator
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PALASZEWSKI, STEPHEN JOHN.
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Contributor
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Latif M. Jiji
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Date
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1980
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Mechanical
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Abstract
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A new three-dimensional model for predicting the flow and thermal characteristics of spray units is presented. The new model eliminates many of the more serious shortcomings of current theoretical approaches. In a marked departure from present theories, which are based in the large on the behavior of an average droplet in some uniform average environment, the new model examines the local variation in properties of both the air and the droplets throughout the flow field encompassing the spray umbrella. The model allows the air streamlines and droplet trajectories to follow substantially different paths and is able to determine the local change in the environment of the droplets throughout their motion. The conservation equations to determine the local absolute humidity, velocity and dry-bulb temperature of the air-vapor phase are written in Lagrangian form where the droplets are treated as spatially varying sources of mass, momentum and energy. Source strength is determined by the interaction between the air-vapor and droplet phases. The analysis takes into consideration stable and unstable meteorological conditions, turbulent mixing in the atmospheric surface layer and non-uniform upwind and local air-velocity profiles.;To illustrate its general applicability, model predictions of droplet return temperature along the spray perimeter were compared with data for two substantially different sprays used for power plant cooling. Predictions of downwind wet-bulb temperature were compared with available data. Good agreement was observed.;A parametric study was carried out to determine an optimum spray unit design. It was found that substantial improvements in the cooling obtained for a given spray power input can be achieved over currently used floating spray modules. It was shown that, for summer design conditions, the cooling obtained from a single spray of the Powered Spray Module can be realized by an alternate spray unit design requiring only one-half the power input.;The new model for spray units can be extended to predict the cooling performance of a pass of sprays aligned in the wind direction. The performance of an entire spray canal can be obtained by incorporating the model for a pass of sprays into a system model.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Engineering
