Untersuchung von Verbesserungspotentialen hermetischer Kolbenkompressoren mit Hilfe numerischer Methoden

Translated title of the contribution: Investigation of potentials for improvement in hermetic reciprocating compressors using numerical simulations

Johann Wilfried Hopfgartner

Research output: ThesisDoctoral Thesis


n the last years, the importance of numerical simulations in the development process of hermetically sealed reciprocating compressors for household appliances has increased significantly. Beside experiments, these simulations are crucial to understand the complex interactions inside the compressor and to assess different measures for improving the compressor efficiency reliably.
One of the most critical parts of reciprocating compressors are their reed valves. These cheap and simple steel valves have major influence on noise emissions, lifetime and efficiency of the compressor. Especially the suction valve has a big potential for improvement. In contrast to the discharge valve, that stays open during the whole discharge process, the suction valve flutters. Thus, it hits the valve seat several times during one suction phase and causes pressure fluctuations and noise emissions. In addition, this oscillating motion of the suction valve is responsible for a considerable part of the thermodynamic losses inside the compressor and thus, the focus of this work was laid on the reduction of the suction losses.

The aim of this work is the analysis of the flow losses caused by the suction valve. Therefore, the refrigerant flow through the hermetically sealed compressor is calculated using three-dimensional CFD-simulations. The mutual interaction between flow and valve dynamics is considered using so-called Fluid-Structure-Interactions. Especially for calculating the suction valve, an approach which is able to model the exact movement as well as the influence of several forces acting on the valve (preload, oil stiction force, contact, etc.), must be used.
Since no commercial structural analysis program is available, which fulfils all requirements, a program based on finite elements has been written for this work. This program is designed for dynamic, nonlinear structural analysis and it is coupled with a commercially available CFD-program. By means of measurements, the suitability of the whole simulation approach is verified. Following, this approach is used to investigate different measures to reduce the flow losses caused by the suction valve. Beside the ability to increase the compressors efficiency, also economic aspects are discussed.
Translated title of the contributionInvestigation of potentials for improvement in hermetic reciprocating compressors using numerical simulations
Original languageGerman
QualificationDoctor of Technology
  • Almbauer, Raimund, Supervisor
Award date18 Dec 2017
Publication statusPublished - 29 Nov 2017

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