Lubrication in Refrigeration Systems: Performance of Journal Bearings Lubricated with Oil and Refrigerant Mixtures

Grando, F. P.; Priest, Martin; Prata, A. T.

doi:10.1016/s0167-8922(05)80050-1

Cited by 8 publications

(4 citation statements)

References 14 publications

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“…Grando et al [57] studied lubrication in presence of refrigerant dissolved in the oil for a steadily loaded partial journal bearing. It was observed that, under the same operating conditions, load capacity and friction force are 22% larger for pure oil.…”

Section: Resultsmentioning

confidence: 99%

Thermo-hydrodynamic analysis of journal bearings operating with non-Newtonian oils

da Silva Cardoso,

Salvaro,

Klein

et al. 2024

J Braz. Soc. Mech. Sci. Eng.

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In recent years, sustainability has been one of the topics of major concern in technological progress, and reducing energy consumption is one of the biggest challenges. The refrigeration industry is responsible for about 20% of the overall electricity used worldwide. The miniaturization, mass reduction and increased rotation speeds lead to higher shear rates. In turn, at these levels, many oils may exhibit non-Newtonian behaviors. The ability to assess non-Newtonian effects can help in choosing and developing more e cient lubricants, where even small increases in e ciency can represent signi cant energy savings. Thus, this paper investigates the effects of using different non-Newtonian oils in a typical journal bearing of a household refrigerator compressor. For this purpose, a thermo-hydrodynamic model was proposed where the modi ed Reynolds equation for uids obeying the power law coupled with the energy equation are solved using the nite volume method in an iterative process. The cavitation boundary is calculated using the equation of conservation of mass and updated at each iteration. The parameters of the power law curve tting were obtained from experimental data tting. The results obtained show that even for small deviations from Newtonian behavior, signi cant variations in load capacity and friction force can be observed. Under the same operating conditions, the load capacity and friction force are 67% and 64%, respectively, lower for the bearing operating with an alkylbenzene oil than with a polyolester oil, while the consistency parameter at T o (m 0 ) is 90% lower.

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Section: Resultsmentioning

confidence: 99%

Thermo-hydrodynamic analysis of journal bearings operating with non-Newtonian oils

da Silva Cardoso,

Salvaro,

Klein

et al. 2024

J Braz. Soc. Mech. Sci. Eng.

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“…However, the gas is not reabsorbed in the liquid if film pressure increases. Further discussion of this assumption can be found in reference [19,20].…”

Section: Mathematical Modellingmentioning

confidence: 99%

“…The current authors have proposed a numerical two-phase model considering cavitation from the release of gas and explored it in the study of partial journal bearings, where the difference between modelling considering pure oil or oil -refrigerant as the lubricant was discussed [19]. The model was also applied to long journal bearings.…”

Section: Introductionmentioning

confidence: 99%

Lubrication in refrigeration systems: Numerical model for piston dynamics considering oil-refrigerant interaction

Grando

Priest

Prata

2006

Proceedings of the Institution of Mechanical Engineers, Part J:

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Piston dynamics plays a fundamental role in several processes related to the operation of hermetic reciprocating compressors used in refrigeration. For example, the refrigerant leakage through the radial clearance between piston and cylinder, which reduces compressor pumping efficiency, and also the viscous friction associated with the lubricant film in the radial clearance, which is related to energy consumption. It is important to optimize such variables, ensuring at the same time smooth operation of the piston in its reciprocating motion, minimizing wear and increasing lifetime. In this context, numerical models studying piston dynamics provide a useful tool for engineering design. These models usually consider an oil film filling the piston-cylinder clearance and operating in the hydrodynamic regime. Determining cavitation conditions occurring along the ringless piston represents an additional difficulty in modelling. As refrigerant is present in the compressor environment, it inevitably interacts with the oil, changing lubricant characteristics. The refrigerant can dissolve in the oil at higher pressures, reducing viscosity, and can be released at lower pressures, leading to a two-phase flow. This work explores how the interaction of oil and refrigerant affects piston dynamics, using a numerical model that considers as the lubricant a mixture of oil and refrigerant with variable properties. Comparing the results with simulations where pure oil is considered as the lubricant and a cavitation criterion is adopted, significant differences were observed in predicting piston trajectory and power consumption along the cycle.

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“…The Grando group at the University of Leeds has published a number of articles on cavitation and multi-phase flow modeling in journal bearings [40][41][42]. They reported that mixtures of lubricant with dissolved HFC-134a -which results in a reduction of the mixture viscosity -perform similarly to that of pure lubricant in terms of the pressure distributions across the support region, indicating no detrimental effects in the bearing as a result of the dissolved solute or multi-phase flow.…”

Section: Effects Of Dissolved Solutes On Lubricant Performancementioning

confidence: 99%

Gas-Expanded Lubricants for Increased Energy Efficiency and Control in Rotating Machinery

Weaver¹

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Lubrication in Refrigeration Systems: Performance of Journal Bearings Lubricated with Oil and Refrigerant Mixtures

Cited by 8 publications

References 14 publications

Thermo-hydrodynamic analysis of journal bearings operating with non-Newtonian oils

Thermo-hydrodynamic analysis of journal bearings operating with non-Newtonian oils

Lubrication in refrigeration systems: Numerical model for piston dynamics considering oil-refrigerant interaction

Gas-Expanded Lubricants for Increased Energy Efficiency and Control in Rotating Machinery

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