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Lubricities of fuels for CI engines
Fuel 112 (2013) 587
Contents lists available at SciVerse ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Letter to the Editor Lubricities of fuels for CI engines
A paper in press with this journal and accessible via Science Direct [1] informs a reader of the ‘reduced lubricity’ of ultra low sulphur diesel (ULSD) fuels , and states that blending of a mineral diesel with a biodiesel can ‘ensure adequate lubricity’. This possibly requires clarification. Lubricity is a measure of the extent to which abrasion caused by the movement of one metal surface against another is mitigated by a particular hydrocarbon liquid. Lubricity is determined in an apparatus in which a steel ball rotates whilst in contact with a fixed steel plate, the entire assembly being immersed in the liquid of interest. The ‘scar diameter’ on the fixed steel plate after such a test, units microns, is termed the lubricity. A liquid affording good lubrication will give rise to a small scar diameter. It therefore follows that the lower the value of the lubricity in these terms the more ‘lubricating’ the liquid is. As an example of this anomaly, in a recent paper in this journal [2] diameters of 325 and 350 lm are described as being increases on a value of 470 lm. In general a lubricity of 500 lm or lower is aimed for with diesel fuels. The problem with ULSD to which the authors of [1] refer is exemplified by the value of 581 lm for a particular ULSD [3]. So lubricities tend to be high for ULSD, and the ‘reduced lubricity’ in
0016-2361/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2012.01.019
[1] is better expressed ‘reduced lubrication’. Similarly ‘adequate lubricity’ should be taken to mean ‘sufficiently low lubricity’ according to the definition in the previous paragraph. Sadly this confusion due to the inverse relationship between lubricity and lubrication seems to be proliferating. I have just pointed it out [4] in a paper in another major journal. References [1] Encinar JM, Gonzalez JF, Martinez G, Sanchez N, Pardal A. Soybean oil transesterification by the use of a microwave flow system. Fuel 2012;95: 386–93. [2] Tracy NI, Chen D, Crunkleton DW, Price GL. Hydrogenated monoterpenes as diesel fuel additives. Fuel 2009;88:2238. [3]. [4] Jones JC. The lubricity of glycerine. Trans Inst Chem Eng Part B: Process Safety Environ Protect, submitted for publication.
J.C. Jones School of Engineering, University of Aberdeen, United Kingdom E-mail address: [email protected] Available online 3 February 2012
Contents lists available at SciVerse ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Letter to the Editor Lubricities of fuels for CI engines
A paper in press with this journal and accessible via Science Direct [1] informs a reader of the ‘reduced lubricity’ of ultra low sulphur diesel (ULSD) fuels , and states that blending of a mineral diesel with a biodiesel can ‘ensure adequate lubricity’. This possibly requires clarification. Lubricity is a measure of the extent to which abrasion caused by the movement of one metal surface against another is mitigated by a particular hydrocarbon liquid. Lubricity is determined in an apparatus in which a steel ball rotates whilst in contact with a fixed steel plate, the entire assembly being immersed in the liquid of interest. The ‘scar diameter’ on the fixed steel plate after such a test, units microns, is termed the lubricity. A liquid affording good lubrication will give rise to a small scar diameter. It therefore follows that the lower the value of the lubricity in these terms the more ‘lubricating’ the liquid is. As an example of this anomaly, in a recent paper in this journal [2] diameters of 325 and 350 lm are described as being increases on a value of 470 lm. In general a lubricity of 500 lm or lower is aimed for with diesel fuels. The problem with ULSD to which the authors of [1] refer is exemplified by the value of 581 lm for a particular ULSD [3]. So lubricities tend to be high for ULSD, and the ‘reduced lubricity’ in
0016-2361/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2012.01.019
[1] is better expressed ‘reduced lubrication’. Similarly ‘adequate lubricity’ should be taken to mean ‘sufficiently low lubricity’ according to the definition in the previous paragraph. Sadly this confusion due to the inverse relationship between lubricity and lubrication seems to be proliferating. I have just pointed it out [4] in a paper in another major journal. References [1] Encinar JM, Gonzalez JF, Martinez G, Sanchez N, Pardal A. Soybean oil transesterification by the use of a microwave flow system. Fuel 2012;95: 386–93. [2] Tracy NI, Chen D, Crunkleton DW, Price GL. Hydrogenated monoterpenes as diesel fuel additives. Fuel 2009;88:2238. [3]
J.C. Jones School of Engineering, University of Aberdeen, United Kingdom E-mail address: [email protected] Available online 3 February 2012