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Hydrospeicher mit Adsorbentien

Hartig, Jakob (2022):
Hydrospeicher mit Adsorbentien. (Postprint)
In: Forschungsberichte zur Fluidsystemtechnik, 28, Darmstadt, Shaker, ISBN 978-3-8440-8561-7,
DOI: 10.26083/tuprints-00021611,
[Book]

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Item Type: Book
Origin: Secondary publication service
Status: Postprint
Title: Hydrospeicher mit Adsorbentien
Language: German
Abstract:

Hydrospeicher werden in hydro-pneumatischen Federbeinen zur Schwingungsisolation eingesetzt. Ein kompressibles Gas im Hydrospeicher dient als Feder und wird zyklisch komprimiert und expandiert. Wie bei jedem Feder-Masse-System gilt, je niedriger die Federsteifigkeit, desto besser die Isolation bei gegebener Masse. Die Federsteifigkeit sinkt allerdings mit steigendem Bauvolumen des Hydrospeichers.

Am Institut für Fluidsystemtechnik entstand die Idee, Hydrospeicher durch das Einbringen hochporöser Adsorbentien wie Aktivkohle, bei gleicher Steifigkeit kleiner bauen zu können. In Abhängigkeit des Drucks lagern sich Gasmoleküle an die Oberfläche der Adsorbentien an und tragen nicht mehr zum Gasdruck bei. Die Steifigkeit der Hydrospeicher sinkt. Allerdings wird bei Adsorption Wärme frei, die insbesondere bei schneller Anregung und damit isentroper Zustandsänderung den Effekt der Steifigkeitsreduktion teilweise wieder aufhebt.

Diese Arbeit beantwortet mit Hilfe zweier Modelle und Messungen die Frage, wie groß das Potential zur Bauraumreduktion durch Adsorbentien in hydro-pneumatischen Federbeinen ist.

Alternative Abstract:
Alternative AbstractLanguage

Hydraulic accumulators are hydraulic components on which the hydraulic fluid can perform work by compressing the gas contained in the accumulator. As soon as the compressed gas relaxes, the hydraulic accumulator performs work on the hydraulic fluid. Albeit somewhat imprecise, hydraulic accumulators are therefore energy storage systems. In commercial vehicles, hydraulic accumulators are used in hydro-pneumatic suspension struts for vibration isolation. The compression and expansion described at the beginning takes place periodically. As with any spring-mass system, the lower the spring stiffness, the better the isolation for a given mass. However, the spring stiffness decreases with the construction volume of the hydraulic accumulator.

At the Chair of Fluid Systems, therefore, the idea arose to incorporate highly porous adsorbents such as activated carbon, to reduce the volume of the accumulator without changing its stiffness. In pressure-dependent adsorption, gas molecules adhere to the surface of the adsorbents and thus no longer contribute to the system pressure. The stiffness of the hydraulic accumulators decreases. However, heat is released during adsorption, which partially cancels out the effect of stiffness reduction, especially in the case of rapid excitation and thus isentropic change of state. In this work, the question is answered as to how large the potential is for design space reduction by adsorbents in hydraulic accumulators. Related to this is the question of how to adequately model hydraulic accumulators with adsorbents. From the axioms for mass and energy as well as material equations, ordinary differential equations were derived which describe hydraulic accumulators with adsorbents. The solution in frequency space shows that from the numerous mass and heat transport phenomena in the hydraulic accumulator and the adsorbent bead, the heat transfer to the environment, the heat capacity of the adsorbents and the adsorption equilibrium play the most important role. Comparison of the model with measurements on a prototypical hydraulic accumulator with adsorbents reveals differences between the model and reality that can be attributed to the formation of dynamic temperature boundary layers. This approach leads to a second model with partial differential equations, which qualitatively agrees with the measurements. Both models developed in this work should be understood as upper and lower bounds on the stiffness and hence design space reductions possible with adsorbents.

English
Series: Forschungsberichte zur Fluidsystemtechnik
Series Volume: 28
Place of Publication: Darmstadt
Publisher: Shaker
Collation: XV, 101 Seiten
Classification DDC: 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
Divisions: 16 Department of Mechanical Engineering > Institute for Fluid Systems (FST)
16 Department of Mechanical Engineering > Institute for Fluid Systems (FST) > Designing with Fluids
Date Deposited: 13 Jul 2022 12:29
Last Modified: 11 Nov 2022 09:55
DOI: 10.26083/tuprints-00021611
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-216117
Additional Information:

Zugl.: Technische Universität, Dissertation 2022

TU-Projekt: Diese Arbeit ist entstanden im Projekt SFB805/C9/Beherrschung von Unsicherheit im Hydrauliksystem

Referees: Pelz, Prof. Dr. Peter F. ; Hampe, Prof. Dr. Manfred J.
Date of oral examination: 6 October 2021
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/21611
PPN: 497858088
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