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Oil Lubricant (oil + lubricant)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

Boiling heat transfer coefficient of R22 and an HFC/HC refrigerant mixture in a fin-and-tube evaporator of a window air conditioner

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2010
M. Herbert Raj
Abstract The commonly used refrigerant in unitary type air conditioners is R22 and its phase out schedule in developing countries is to commence from 2015. Many alternatives to R22 are found in published literature in which R407C has similar characteristics to those of R22 except for its zeotropic nature. However, R407C which is an HFC is made compatible with the mineral oil lubricant in the system compressor by the addition of 20% of HC. This HFC/HC mixture called the M20 refrigerant mixture is reported to be a retrofit refrigerant for R22. Though its latent heat value is greater than that of R22, its refrigerating capacity is lower when it is used to retrofit R22 window air conditioners. Hence, a heat transfer analysis was conducted in the evaporator of a room air conditioner, for practically realized heat flux conditions during standard performance testing. The tests were conducted as per the BIS and ASHRAE standards. Kattan,Thome,Favrat maps are used to confirm the flow patterns, which prevail inside the fin-and-tube evaporator in the tested operating conditions. It is revealed that the heat transfer coefficient/heat fluxes are poorer for M20 because of the lower mass flow rate and higher vapor fraction at the entry of the evaporator than that of R22 in the prevailing operating conditions. The heat transfer coefficients of the M20 refrigerant mixture under various test conditions are lower in the range of 14% to 56% than those of R22. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/htj.20299 [source]

Large-scale specimen testing on friction and wear of pure and internally lubricated cast polyamides

LUBRICATION SCIENCE, Issue 3 2006
Pieter SamynArticle first published online: 4 JUL 200
Abstract Due to the casting process for nylons, their composition can easily be modified to cover a wide range of mechanical properties and applications, especially as large wear surfaces in, for example, crane guidances. Presently, selection tests for working conditions up to 40MPa are presented on pure Na-catalysed polyamides, oil-filled polyamides with homogeneous oil dispersions and holes in the surface containing oil lubricant and two types of thermoplastic solid-lubricated polyamides. Pure polyamides are, however, prone to high and unstable sliding at pressures as low as 10MPa with brittle fracture and lumpy transfer. Oil lubrication is not able to remove the sliding instabilities as oil supply to the sliding interface is controlled by migration effects that are restricted by deformation and thermal softening or melting of the polyamide matrix. Although friction and wear are lower and more stable for samples with oil supplied through lubricating holes, additional running-in phenomena are attributed to a relatively thick transfer film that is brittle and easily peels off. A continuous thick molten film or island-like deposition occurs on the polyamide surface. Solid lubricants are able to stabilize friction and lower wear down to the formation of a thin and coherent transfer film. However, increasing the amount of lubricants induces lower mechanical properties and higher deformation of the test samples. The differences in transfer behaviour are discussed with reference to optical microscopy and calculations of bulk and flash temperatures. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Influence of oil type on the performance characteristics of a two-axial groove journal bearing

LUBRICATION SCIENCE, Issue 9 2009
D. M. C. McCarthy
Abstract The use of environmentally adapted lubricants (EALs) is a subject of growing interest to industry as legislation increasingly demands the replacement of mineral oil lubricants. Vegetable-based fluids are widely seen as providing lubricants from a renewable source, as well as meeting demands for improved biodegradability. However, at present, utilization of such fluids is limited due to their rapid oxidation. EALs produced from other base stocks (i.e. synthetic esters) have been shown to provide performance benefits in hydrodynamic thrust bearings. In the present study, a hydrodynamic journal bearing test rig has been employed to compare the performance of three EALs (a VG32 saturated ester, rapeseed base fluid and a propylene glycol dioleate) relative to three mineral turbine oils (ISOVG32, ISOVG46 and ISOVG68) in the hydrodynamic regime. Results are given in terms of temperature, power loss and minimum film thickness. The impact of oil viscosity index is also discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Influence of cylinder-on-plate or block-on-ring sliding configurations on friction and wear of pure and filled engineering polymers

LUBRICATION SCIENCE, Issue 2 2007
P. Samyn
Abstract Polyamides, polyesters and polyacetals are often used in line contacts under reciprocating or continuous sliding. These contacts are simulated on cylinder-on-plate (COP) or block-on-ring (BOR) tribotests. Comparative tests for pure, oil-filled and solid lubricated polymers at 100N and 0.3m/s are presented for relative material classification. Differences are discussed according to the sliding geometries. Thermal effects dominate friction and wear behaviour: the polymer glass transition temperature is exceeded in COP tests while the temperature is lower in BOR tests. Thick and brittle films are observed for pure polymers in BOR tests, promoting higher friction. The test configuration is mainly important for evaluation of internal lubricants. The efficiency of oil-lubricated polymers is not demonstrated in COP tests, while solid lubricants are not efficient in BOR tests. Deformation restricts the diffusion of oil lubricants in COP tests while solid lubricants are deposited on the polymer surface rather than being incorporated in the transfer film in BOR tests. Copyright © 2007 John Wiley & Sons, Ltd. [source]