Influence Of Spray Characteristics Research Articles

Study on the influence of spray characteristics and air flow direction on heat transfer of spray evaporative condenser

Spray cooling is effectively utilized in evaporative condensers to achieve efficient heat and mass transfer transmission, while also effectively preventing performance degradation caused by packing blockage. The heat transfer efficiency is strongly affected by the relative flow direction between the spray and air flow. This work employs computational fluid dynamics to evaluate and examine the heat transfer effects of parallel and countercurrent air and spray flow in evaporative condensers. The findings indicate that increasing spray density and wall temperature enhances heat transfer efficiency. Smaller droplets with lower initial velocity exhibit superior heat transfer capabilities in parallel flow, while smaller droplets also perform well in countercurrent flow as long as the initial velocity is not too high. Additionally, a slight increase in air velocity improves heat transfer efficiency in both parallel and countercurrent flow conditions. It is important to note that the countercurrent condition has a larger heat transfer effect than the parallel flow.

Influence of spray characteristics on heat flux in dual phase spray impingement cooling of hot surface

The effects of variation of spray characteristics (mass flux, inlet pressure, flow rate, nozzle tip to target distance and plate thickness) on heat flux were systematically investigated. The round spray released from a full cone internally mix atomizing nozzle was impinged with a wide range of air and water pressures on stationary hot steel surface of definite dimension. The effect of each parameter was examined while keeping others nearly fixed. Four different plate thicknesses i.e., 4mm, 6mm, 8mm and 10mm were tested and effect of plate thickness on heat transfer was determined. Surface heat flux at each experimental condition was computed from the transient temperature history measured by K-type thermocouples embedded at bottom surface of the plate. The mass impingement density was measured by the help of a simple mechanical patternator. The maximum surface heat flux of 4895.525kW/m2 was achieved at an inlet water pressure of 4bar, air pressure of 3bar and nozzle height of 120mm for an initial temperature of 850°C of the 4mm steel plate.

Influence of spray characteristics on local light gas mixing in nuclear containment reactor applications

The action of spray on the mixing of different gases is used in numerous industrial applications, such as the chemical industry or the nuclear containment. The present paper concerns the impact of a spray on the break-up of a light gas layer (helium) initially confined in the top of a closed volume. Numerical calculations were performed in order to simulate the evolution of the helium concentration when the spray is activated. The objective of the paper is to show how the boundary conditions used for describing the spray can be important on the local gas mixing. Several sensitivity studies were performed that show the importance of the droplet boundary conditions: droplet size distribution, droplet velocity profiles, number of droplet classes, etc. Influence of these parameters on local gas concentration can be even higher than the one induced by a different turbulence model or some numerical parameters. Influence of the nozzle position inside the vessel is also analyzed. Extrapolation to an industrial application based on nuclear reactor containment is then discussed and recommendations are given for CFD simulations on the impact of spray systems on the gas mixing in nuclear reactors.

Influence of spray characteristics on potential spray drift of field crop sprayers: A literature review

Spray drift is a practical consequence of agricultural spraying operations. Because of the agronomical and environmental impacts of this phenomenon, drift has been widely studied and extensive information is available. Here we present a literature review on the relationships between global physical descriptors of agricultural sprays, air conditions and resulting drift, generally studied in wind tunnels. Basic physical factors are droplet size, droplet velocity, and the physicochemical characteristics of the sprayed product. When possible, data available in the literature are collated to draw trends. Contradictory information sometimes appears especially regarding droplet velocity and drift control. The main physical factors consist generally of medians such as Volume Median Diameter (VMD or Dv50) that do not always represent the heterogeneity of a spray and especially the spatial distribution of particle size and velocity. Technological parameters such as nozzle height, spray angle, travel speed are then related to initial physical factors and their contribution to driftability of sprays.

Analysis of Fuel Injection Parameter on Biodiesel and Diesel Spray Characteristics Using Common Rail System

Precise control of fuel injection is essential in modern diesel engines especially in controlling the precise injection quantity, flexible injection timing, flexible rate of injection with multiple injections and high injection pressures. It was known that the fuel-air mixing is mainly influenced by the fuel injection system and injector nozzle characteristics. Thus, mixture formation during ignition process associated with the exhaust emissions. The purpose of this study is to investigate the influence of spray characteristics on the mixture formation. In this study, common rail injector systems with different model of injector were used to simulate the actual mixture formation inside the engine chamber. The optical visualization system was constructed with a digital video camera in order to investigate the detailed behavior of mixture formation. This method can capture spray penetration length, spray angle, spray evaporation and mixture formation process clearly. The spray characteristic such as the penetration length, spray angle and spray area are increasing when the injection pressure increased. The mixture formation can be improved effectively by increasing the injection pressure.

The Influence of Spray Characteristics on Surface Roughness in Minimum Quantity Lubrication Turning

In Minimum Quantity Lubrication machining, cutting fluid is provided as mist. Mist with different velocity and diameter may lead to different cooling, lubrication effect and cutting quality. Thus, cutting quality is highly influenced by spray characteristics in MQL machining. In this study, the mathematics model of mist flow was set up first. Then spray characteristics were tested by a 3-Dimensional Particle Dynamic Analyzer. In order to study the influence of spray characteristics on cutting quality, precision turning of 45 steel was performed by a CNC Super Precision Machine Tool. The results indicate that the lowest surface roughness was obtained by supplying more cutting fluid at proper position for spraying distance of 20mm.