INAUGURAL–DISSERTATION zur Erlangung der Doktorwürde der ...

List of Figures
1.1 A schematic diagram of the spray drying process [3]. . . . . . . . . . . 2
1.2 Chemical structure of polyvinylpyrrolidone (C 6 H 9 NO) n [8]. . . . . . . . 3
1.3 SEM images of spray dried PVP [11]. . . . . . . . . . . . . . . . . . . . 4
1.4 Chemical structure of mannitol (C 6 H 8 (OH) 6 ) [12]. . . . . . . . . . . . . 4
2.1 Sketch of a pressure-atomized spray formation [69, 70]. . . . . . . . . . 11
2.2 A typical log-normal distribution with different values of µ and σ. . . . 21
2.3 Approximation of NDF in QMOM. . . . . . . . . . . . . . . . . . . . . 24
2.4 NDF approximation in DQMOM. . . . . . . . . . . . . . . . . . . . . . 25
2.5 Schematic diagram of stages in single droplet evaporation and drying. . 34
2.6 Droplet breakup mechanisms based on Weber number [69, 178]. . . . . 41
2.7 Droplet collision regimes: (a) bouncing, (b) coalescence [184]. . . . . . . 42
2.8 Droplet collision regimes: (c) reflexive or crossing separation, (d) stretching
separation [184]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.1 Flowchart of the DQMOM computational code. . . . . . . . . . . . . . 52
4.1 Photograph of the water spray formation. . . . . . . . . . . . . . . . . . 56
4.2 Schematic diagram of spray with measurement positions. . . . . . . . . 56
4.3 Experimental surface frequency distribution at cross section 0.14 m (left)
and 0.54 m (right) away from the nozzle exit. . . . . . . . . . . . . . . 57
4.4 Comparison of simulated and measured [199] droplet mass and temperature
profiles for the evaporation of a pure water droplet. . . . . . . . . 58
4.5 Homogeneous and inhomogeneous calculations of DQMOM. . . . . . . 59
4.6 Comparison of QMOM and DQMOM results with experiment. . . . . . 60
4.7 Droplet size distribution of water spray and at t = 0 s, and at t = 1 s
with d 2 law evaporation rate. . . . . . . . . . . . . . . . . . . . . . . . 60
4.8 Velocity profiles of three droplets with different initial radii and velocities
under the influence of drag alone (left) and drag and gravity (right). . . 62
4.9 Effect of liquid inflow rates on Sauter mean diameter computed with
and without coalescence. . . . . . . . . . . . . . . . . . . . . . . . . . . 62