Analysis of the economic and ecological properties of pneumatic actuator systems with pneumatic transformers

  • Analyse der wirtschaftlichen und ökologischen Eigenschaften pneumatischer Antriebssysteme mit pneumatischen Druckwandlern

Merkelbach, Stephan; Murrenhoff, Hubertus (Thesis advisor); Schmitz, Katharina (Thesis advisor)

Düren : Shaker Verlag (2020)
Book, Dissertation / PhD Thesis

In: Reihe Fluidtechnik. D 96
Page(s)/Article-Nr.: xii, 131 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2019

Abstract

Pneumatic drives are used in a wide variety of industrial applications. Recently, the life cycle costs (LCC) of the actuators become more important in investment decisions as the acquisition costs do not necessarily reflect the drives’ economic efficiency. This thesis describes an economic and ecological life cycle analysis of pneumatic actuators. First, the LCC of the drives are estimated based on typical load cycles and compared the LCC of comparable electromechanical actuators. Therefore, the efficiency of both drive types is compared based on the exergy concept. Together with the acquisition costs and further cost elements, the LCC are calculated depending on the load cycles. Furthermore, an assessment of the reduction potential for the exergy demand of the pneumatic drives is executed by an experimental investigation of different exergy saving measures with low installation effort which can reduce the demand for compressed air and working costs immensely while affording relatively low installation effort. In addition to these measures installed in direct vicinity to the drive, nowadays, the operation of the whole pneumatic system at lower pressure gathers growing attention. A lower system pressure leads to a reduction of losses in the compressor. On the downside, the implementation of larger drives to gain the same output force and load stiffness is necessary. Some applications still afford small drives with high force. To avoid the implementation costs of an additional high-pressure system, local pressure boosting by means of pneumatically driven boosters is feasible. For this, double piston boosters are state of the art. Their working principle implies high exergy losses and noise emissions. The thesis presents the development and functional testing of a novel pressure booster concept based on pneumatic radial piston units. The concept is evaluated in a simulation study and a functional model is designed and manufactured. It is examined experimentally and different optimisations to increase its exergy efficiency are implemented and validated. As a conclusion, the impact of low-pressure pneumatic systems including pneumatic boosters on the overall efficiency and the LCC of the drives is estimated. This includes drives working at a reduced driving pressure as well as at boosted high pressure. Facing climate change, the emissions of greenhouse gases (GHG) become more important as an additional parameter for the decision between different drive technologies. Besides the economic analysis of the drives, the thesis shows the results of a life cycle analysis focusing on the GHG emissions for one exemplary actuator including its whole life cycle from production of the materials up to the recycling of the components after their end-of-life.

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