A Numerical Friction Loss Analysis of the Journal Bearings in a Hermetic Reciprocating Compressor

Stefan Posch, Johann Wilfried Hopfgartner, Martin Heimel, Erwin Berger, Raimund Almbauer, Peter Schöllauf

Research output: Chapter in Book/Report/Conference proceedingConference contributionResearchpeer-review

Abstract

In addition to the electrical and the thermodynamic losses in hermetic compressors, mechanical losses have a significant influence on the performance of the compressor. In the present paper the friction losses in the journal bearings of a hermetic reciprocating compressor are investigated using numerical methods. A dynamic model is set up to solve the Reynolds equation using a finite volume approach to calculate the pressure field in each journal bearing. The calculation of the fluid film thickness is accomplished with the formulas of the parallel gap. The resulting hydrodynamic forces are equated with forces obtained by a dynamic multibody model of the compressor crank drive to calculate the transient orbit movement of the bearing. Based on the movement of the crankshaft at steady-state conditions, the shear stresses in the gap between crankshaft and housing can be calculated. Thus the cycle averaged friction power loss can be determined. To consider effect such as surface roughness of the bearings or possible contacts between the solids, correlations found in the literature are implemented. The present method is used to assess the friction power loss of the journal bearings during the operation with different oil viscosities. The simulated data is verified with simple analytical friction loss calculations based on shear stresses in the Couette flow between bearing and housing.
Original languageEnglish
Title of host publication16th International Refrigeration and Air Conditioning Conference at Purdue
Pagesx-x
Publication statusPublished - 2016

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Reciprocating compressors
Journal bearings
Bearings (structural)
Friction
Compressors
Crankshafts
Shear stress
Dynamic models
Reynolds equation
Film thickness
Numerical methods
Orbits
Hydrodynamics
Surface roughness
Thermodynamics
Viscosity
Fluids

Cite this

Posch, S., Hopfgartner, J. W., Heimel, M., Berger, E., Almbauer, R., & Schöllauf, P. (2016). A Numerical Friction Loss Analysis of the Journal Bearings in a Hermetic Reciprocating Compressor. In 16th International Refrigeration and Air Conditioning Conference at Purdue (pp. x-x)

A Numerical Friction Loss Analysis of the Journal Bearings in a Hermetic Reciprocating Compressor. / Posch, Stefan; Hopfgartner, Johann Wilfried; Heimel, Martin; Berger, Erwin; Almbauer, Raimund; Schöllauf, Peter.

16th International Refrigeration and Air Conditioning Conference at Purdue. 2016. p. x-x.

Research output: Chapter in Book/Report/Conference proceedingConference contributionResearchpeer-review

Posch, S, Hopfgartner, JW, Heimel, M, Berger, E, Almbauer, R & Schöllauf, P 2016, A Numerical Friction Loss Analysis of the Journal Bearings in a Hermetic Reciprocating Compressor. in 16th International Refrigeration and Air Conditioning Conference at Purdue. pp. x-x.
Posch S, Hopfgartner JW, Heimel M, Berger E, Almbauer R, Schöllauf P. A Numerical Friction Loss Analysis of the Journal Bearings in a Hermetic Reciprocating Compressor. In 16th International Refrigeration and Air Conditioning Conference at Purdue. 2016. p. x-x
Posch, Stefan ; Hopfgartner, Johann Wilfried ; Heimel, Martin ; Berger, Erwin ; Almbauer, Raimund ; Schöllauf, Peter. / A Numerical Friction Loss Analysis of the Journal Bearings in a Hermetic Reciprocating Compressor. 16th International Refrigeration and Air Conditioning Conference at Purdue. 2016. pp. x-x
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N2 - In addition to the electrical and the thermodynamic losses in hermetic compressors, mechanical losses have a significant influence on the performance of the compressor. In the present paper the friction losses in the journal bearings of a hermetic reciprocating compressor are investigated using numerical methods. A dynamic model is set up to solve the Reynolds equation using a finite volume approach to calculate the pressure field in each journal bearing. The calculation of the fluid film thickness is accomplished with the formulas of the parallel gap. The resulting hydrodynamic forces are equated with forces obtained by a dynamic multibody model of the compressor crank drive to calculate the transient orbit movement of the bearing. Based on the movement of the crankshaft at steady-state conditions, the shear stresses in the gap between crankshaft and housing can be calculated. Thus the cycle averaged friction power loss can be determined. To consider effect such as surface roughness of the bearings or possible contacts between the solids, correlations found in the literature are implemented. The present method is used to assess the friction power loss of the journal bearings during the operation with different oil viscosities. The simulated data is verified with simple analytical friction loss calculations based on shear stresses in the Couette flow between bearing and housing.

AB - In addition to the electrical and the thermodynamic losses in hermetic compressors, mechanical losses have a significant influence on the performance of the compressor. In the present paper the friction losses in the journal bearings of a hermetic reciprocating compressor are investigated using numerical methods. A dynamic model is set up to solve the Reynolds equation using a finite volume approach to calculate the pressure field in each journal bearing. The calculation of the fluid film thickness is accomplished with the formulas of the parallel gap. The resulting hydrodynamic forces are equated with forces obtained by a dynamic multibody model of the compressor crank drive to calculate the transient orbit movement of the bearing. Based on the movement of the crankshaft at steady-state conditions, the shear stresses in the gap between crankshaft and housing can be calculated. Thus the cycle averaged friction power loss can be determined. To consider effect such as surface roughness of the bearings or possible contacts between the solids, correlations found in the literature are implemented. The present method is used to assess the friction power loss of the journal bearings during the operation with different oil viscosities. The simulated data is verified with simple analytical friction loss calculations based on shear stresses in the Couette flow between bearing and housing.

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