J5 Spontane Kondensation und Aerosolbildung

Ehrler, Friedrich; Schaber, Karlheinz

doi:10.1007/978-3-642-19981-3_67

Cited by 1 publication

(3 citation statements)

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“…The saturation S describes supersaturated states of vapour with p V being the pressure of vaporous components and pV,sat the saturation pressure of condensable components corresponding to the vapour temperature T V . 17 …”

Section: Condensation Phenomenamentioning

confidence: 99%

“…This heterogeneous condensation affects the spontaneous condensation process, especially at a high particle number density of impurities. 17 The point of noticeable condensation onset is also referred to as the Wilson point in the literature.…”

Section: Condensation Phenomenamentioning

confidence: 99%

“…1–3,16 The first formulation of nucleation rate J was later improved by adding factors for non-isothermality Θ and non-equilibrium Z. 17,18 The product of the condensation coefficient α c and the first bracketed expression (collision probability) gives the number of colliding monomers with the critical cluster, given the particle density n V , mean thermal velocity c¯V and cluster surface area O *. The exponential expression denotes the formation probability of critical clusters with the enthalpy of formation ΔG* and Boltzmann constant k .…”

Section: Condensation Phenomenamentioning

confidence: 99%

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Simulation-based investigation of spontaneous condensation in steam-driven screw expanders

Grieb

Brümmer

2019

Proceedings of the Institution of Mechanical Engineers, Part E:

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Condensation and its effects on turbomachinery operation are well understood and have been widely investigated. However, only little scientific work on condensation in positive displacement machines has been published. Although, depending on machine type, high expansion rates and, as a consequence, significant supersaturation can be achieved for working fluids with a negative saturation vapour curve. In this paper, the effects of spontaneous steam condensation in screw expanders are discussed. Classical nucleation theory is used for the thermodynamic simulation of operational behaviour. The study shows at which point during the expansion phase spontaneous condensation can be expected and typical nucleation rates are determined. The impact of released latent heat during expansion on chamber states is depicted. Furthermore, a comparison of purely metastable expansion with equilibrium expansion is provided in order to show the full-range discrepancies. Additionally, the influence of internal leakage and throttling effects during the inlet phase on the course of spontaneous condensation and droplet growth is analysed. Typical operating parameters are widely varied in simulation so as to identify the impact of steam parameters and expander parameters on the condensation process.

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