Spray Particle Size Research Articles

On a special application of the truncation problem

A special application of the truncation problem is presented in connection with constructing a model for the analysis of the fine aerosol spray particle size distribution sampled by an impact method. The relationship between the diameter distribution of images recorded on a photograph and the actual spherical particle diameter distribution is analyzed. The problem of estimating the parameters of the actual diameter distribution using the induced information is transformed to estimating the parameters of a truncated distribution with known or unknown truncation point. The derived general solution is implemented to two specified particle size distributions.

Ultra-Low-Volume Applications of Synergized Pyrethrins for Stored-Product Insect Control1

Spray particle size distribution within a closed room and target pest mortality to ultra-low-volume (ULV)-applied synergized pyrethrins were studied, using the confused flour beetle, Tribolium confusum Jacquelin duVal, and rice weevil, Sitophilus oryzae (L.). The insects were given various degrees of harborage and exposed for different time intervals up to 2 h during and immediately after application, or exposed 15 or 60 min after application. ULV treatments were most effecttve immediately after application. Insects exposed 15 min after application were not effectively controlled. ULV treatments did not penetrate well into completely enclosed areas. Also, less volume settled within open and partly open cabinets than on completely exposed surfaces. Increased exposure time led to greater mortality in protected areas.

ULV Particle Size Deposition on Immature Greenhouse Whiteflies123

A scanning electron microscope procedure was used to determine which spray particle sizes deposit effectively on immatures of Trialeurodes vaporariorum (Westwood) following ULV applications by 2 different application techniques. Spray application techniques which maximize use of machine airblast to create air circulation within the foliage caused deposit of larger spray particles (i.e., allowed a larger portion of the spray particle size output to deposit successfully) on the immature stages. An optimum spray particle size of 15–25 µm (mass median diam) is supported for ULV applications in greenhouse floriculture.

Spray Particle Size Distribution in Greenhouse ULV Applications to Poinsettia12

Spray particle size distribution was studied in dense poinsettia foliage after mechanical aerosol (or ULV) applications of mineral oil resmethrin formulations for control of greenhouse whitefly, Trialeurodes vaporariorum (Westwood), in a commercial greenhouse. A systematic arrangement of Teflon®-coated microscope slide sampling units was used to monitor both spray droplet distribution in horizontal and vertical directions in the foliage and particle size deposition on upper and lower leaf surfaces at each sampling position. Seven distinct application types, consisting of 2 avg particle size ranges (10–13 and 30–40 μ m mass median diam (MMD)) and 4 application techniques in different comhinations, were tested in a total of 19 spray tests. Microscope slide analysis provided MMD and avg deposition volume per unit of slide area data. Statistical analyses of these data indicated that 15–25 μ m MMD was the optimum spray particle size for greenhouse whitefly control and that application technique was an important factor. Spraying techniques that maximize the amount of air circulation within the foliage during application were most efficient.

The Reaction of a Molten Sodium Spray with Air in an Enclosed Volume Part I. Experimental Investigation

Molten sodium (623 to 69°K) was injected by a pneumatic, piston spray-injector into a closed reaction chamber containing dry air or dry air-nitrogen mixtures. The rate of the pressure rise resulting from the sodium-air burning reaction was measured during the spraying interval. The pressure-rise rate was a measure of the reaction rate. The spray particle size had the most pronounced effect on the reaction rate, which increased as the particle size decreased. Increasing the spray velocity resulted in a modest increase in the reaction rate. The reaction rate decreased slowly as the oxygen content of the atmosphere was lowered until, at an oxygen concentration of 4 mol%, there was no visible burning.

XV. The influence of spray particle size and distribution in the combustion of oil droplets

Summary The evaporation of liquid sprays is examined theoretically using the known law of size distribution in a spray and an experimental law concerning the effect of size on the evaporation of singie droplets. The investigation is concerned not with the mechanism of evaporation, but only with the effects of size and distribution. The mean diameter and rate of evaporation of given distributions are evaluated, and also the variation of the volume of a spray as evaporation proceeds, for all sprays likely to be met with in practice. The effect of distribution on combustion intensity is discussed, and the investigation shows what characteristics are desirable in a spray from the point of view of combustion. The data sheets provided should assist in correlating experimental evidence of the effects of atomiser characteristics on combustion losses and flame length, etc.