Dråpestørrelse

Dråpestørrelse, or droplet size, is a fundamental parameter in spray and aerosol science describing the size of individual droplets produced by atomization processes such as spray nozzles, nebulizers, humidifiers, or natural phenomena like rain. Droplets are distributed over a range of sizes, and their behavior depends on this distribution. Commonly used descriptors include the volume median diameter (Dv50), the number median diameter (Dn50), and the Sauter mean diameter (D32). Diameters are typically given in micrometers (µm).

Droplet size is usually characterized by size distributions rather than a single value. Techniques to measure and describe these distributions include laser diffraction, optical imaging, and cascade impactors. Each method provides different metrics (volume-based, number-based) that are used to assess applications such as dose delivery, coverage, or drift.

Several factors influence dråpestørrelse. The design and type of atomizer or nozzle, operating pressure, and fluid properties—viscosity, surface tension, volatility—play major roles. Environmental conditions such as air speed, temperature, and ambient humidity also affect evaporation and breakup. Different atomization modes (for example, pressure-swirl, twin-fluid, or air-assisted systems) produce distinct size ranges.

Applications and implications span multiple fields. In inhalation therapy, droplet size determines where particles deposit in the respiratory tract. In agriculture, droplet size affects spray coverage and off-target drift. In industrial processes and manufacturing, it influences coating uniformity and deposition. Smaller droplets can remain airborne longer and travel farther, while larger droplets deposit more quickly; evaporation and hygroscopic effects can further modify the effective size during transport.