The Influence of the Chemical Structure of Synthetic Hydrocarbons and Alcohols on the Lubricity of Ci Engine Fuels and Aviation Fuels

Abstract

The paper covers the mechanism of lubrication layer formation by fuels containing synthetic hydrocarbons and alcohols. Development of alternative fuels containing FAME, alcohols, and synthetic hydrocarbons has increased the interest in the mechanism of lubrication of fuelling systems parts. Fuel lubricity tests have been conducted using the HFRR and BOCLE testing rigs. Fuels under testing, both for CI engines and for aviation turbine ones, contained synthetic components: saturated hydrocarbons both of even and odd number of carbon atoms, and butanol, isomers. These components have been added to conventional fuels, such as diesel fuel and Jet A-1 fuel at the concentration of 0–20% (V/V). All fuels under testing contained commercially available lubricity improvers (carboxylic acid). Test results were analysed using model αi described in [L. 6, 7]. As a result of the analysis, it has been found that the liquid phase, which is a lubricating film, should contain agglomerates or molecular clusters responsible for the transport of energy introduced into lubricating film by electrons emitted from metal surface. The mechanism enabling a description of the effect of base fuel without lubricity improvers on efficiency of such additives has been suggested.

The Indirect Tribological Role of Carbon Nanotubes Stimulating Zinc Dithiophosphate Anti-Wear Film Formation

“…The main experiment of this research study was the High Frequency Reciprocating Rig (HFRR) test [ 37 ]. The HFRR test is primarily dedicated to assessment of diesel fuel lubricity, but it is also useful for testing other lubricants [ 38 ]. During HFRR tests, both the dynamic friction coefficient and film thickness are simultaneously recorded.…”

Tribochemical Interactions between Carbon Nanotubes and ZDDP Antiwear Additive during Tribofilm Formation on Uncoated and DLC-Coated Steel

“…The results of the authors' earlier research [2,3] clearly indicate how important the properties of lubricants are in the formation of a lubricating film. The tribological tests, carried out using a high-frequency reciprocating rig (HFRR) [4], reveal that the presence of an antistatic additive (ASA) affects the effectiveness of ZDDP, decreasing the coefficient of friction and wear and, what is more, increasing the thickness of the lubricating film.…”

“…According to adopted methodology, each lubricant has been tested three times using TRB 3 tribotester equipped with uncoated disc and three times using TRB 3 tribotester equipped with a disc coated by a-C:H. It was found that the values of the results-coefficient of friction and linear wear-obtained for given lubricant and given kind of disc (uncoated or coated) were very similar. In this situation, one was chosen from the results obtained for each lubricant and each kind of disc.…”

“…The results of the authors' previous research, described in [2,3], were used to formulate a concept of the mechanism of lubricating film formation. The postulated mechanism assumes interactions between the ZDDP molecules, the molecules of the other lubricant components, capable of energy transfer (e.g., the ASA additive), and the material of the solid elements in contact.…”