N.W.M. Zulkifli

Tribological performance of nanoparticles as lubricating oil additives

The prospect of modern tribology has been expanded with the advent of nanomaterial-based lubrication systems, whose development was facilitated by the nanotechnology in recent years. In literature, a variety of nanoparticles have been used as lubricant additives with potentially interesting friction and wear properties. To date, although there has been a great deal of experimental research on nanoparticles as lubricating oil additives, many aspects of their tribological behavior are yet to be fully understood. With growing number of possibilities, the key question is: what types of nanoparticles act as a better lubricating oil additive and why? To answer this question, this paper reviews main types of nanoparticles that have been used as lubricants additives and outlines the mechanisms by which they are currently believed to function. Significant aspects of their tribological behavior such as dispersion stability and morphology are also highlighted.

Experimental assessment of non-edible candlenut biodiesel and its blend characteristics as diesel engine fuel

Exploring new renewable energy sources as a substitute of petroleum reserves is necessary due to fulfilling the oncoming energy needs for industry and transportation systems. In this quest, a lot of research is going on to expose different kinds of new biodiesel sources. The non-edible oil from candlenut possesses the potential as a feedstock for biodiesel production. The present study aims to produce biodiesel from crude candlenut oil by using two-step transesterification process, and 10%, 20%, and 30% of biodiesel were mixed with diesel fuel as test blends for engine testing. Fourier transform infrared (FTIR) and gas chromatography (GC) were performed and analyzed to characterize the biodiesel. Also, the fuel properties of biodiesel and its blends were measured and compared with the specified standards. The thermal stability of the fuel blends was measured by thermogravimetric analysis (TGA) and differential scan calorimetry (DSC) analysis. Engine characteristics were measured in a Yanmar TF120M single cylinder direct injection (DI) diesel engine. Biodiesel produced from candlenut oil contained 15% free fatty acid (FFA), and two-step esterification and transesterification were used. FTIR and GC remarked the biodiesels’ existing functional groups and fatty acid methyl ester (FAME) composition. The thermal analysis of the biodiesel blends certified about the blends’ stability regarding thermal degradation, melting and crystallization temperature, oxidative temperature, and storage stability. The brake power (BP), brake specific fuel consumption (BSFC), and brake thermal efficiency (BTE) of the biodiesel blends decreased slightly with an increasing pattern of nitric oxide (NO) emission. However, the hydrocarbon (HC) and carbon monoxides (CO) of biodiesel blends were found decreased.

The effect of palm oil trimethylolpropane ester on extreme pressure lubrication

This paper presents the experimental results for the extreme pressure characteristics of a palm oil-based trimethylolpropane (TMP) ester blended with paraffin oil obtained using a four-ball machine. The load and speed of the sample were set between 20–120u2009kg and 1770u2009rpm, respectively. TMP ester produced from palm oil is biodegradable and has high lubricity properties, such as a higher flash point temperature and viscosity index. It has an affinity to surface asperities, which reduces wear between sliding contacts. Based on the calculation, it was found that majority of the oils in boundary regime and mixed elastrohydrodynamic regime. For the same contact load, the film thickness with TMP100 is 70% thicker than that with paraffin oil. In addition to that, test results revealed that (1) for all the used lubrication oils, TMP ester blended with paraffin provide better surface protection compared to paraffin oil. (2) Even though, TMP100 has the highest film thickness, at low load the wear is higher. Surface morphology test was conducted using scanning electron microscope and surface roughness tester. It was found that severe corrosive wear occurred at TMP100 which is probably due to the high oxygen content compared to other lubricant.

A review on the effect of bioethanol dilution on the properties and performance of automotive lubricants in gasoline engines

Owing to the growing concern over the depletion of fossil fuels and the increasing rate of greenhouse gas emissions which will lead to global warming, many researchers are now dedicated to producing alternative biofuels in order to help address the above-mentioned issues. Bioethanol is one of the biofuels which has gained much attention for use in existing gasoline engines and nowadays, bioethanol is blended with gasoline at higher proportions since the use of bioethanol helps reduce exhaust emissions such as soot, carbon oxides and unburned hydrocarbons. However, the use of bioethanol has undesirable effects on the tribological properties of the fuel blend, and it is possible that the automotive lubricant will be contaminated with diluted oxygenated bioethanol during engine operations. Moreover, the addition of bioethanol into gasoline alters the properties of the fuel, which in turn affects the vehicle performance. Since bioethanol has a significantly higher boiling point and latent heat of vaporization compared to gasoline, it is likely that the level of bioethanol dilution in the automotive lubricant will increase significantly, which in turn degrades the quality of the lubricant to protect the engine components against friction and wear. The purpose of this review paper is to highlight the physicochemical properties of bioethanol and its blends as well as the effect of bioethanol dilution on the properties and performance of automotive lubricants in gasoline engines. Based on the key findings, it can be concluded that bioethanol dilution has a significant effect on the properties of automotive lubricants, particularly on oil consumption, corrosion, wear and sludge, which will lead to engine failure. However, the contamination of automotive lubricants can be prevented by the addition of additives such as dispersants, detergents or antioxidants, which will improve the lubricity and performance of the engine oil.

Enhancing vehicle’s engine warm up using integrated mechanical approach

Transportation sector covers a large portion of the total energy consumption shares and is highly associated to global warming. Growing concern over the harmful gases being emitted from vehicles and their environmental implications has urged the need for pollutant reduction through more efficient engines. Good engine thermal management especially during cold-start warm up phase has been proven to enhance the engine efficiency in terms of fuel economy and greenhouse emissions specifically. In this study, the viability engine split cooling system was tested in two separate test. The parameters of interest include coolant and transmission temperature as these both parameters indicate the internal engine condition and highly associated with engine efficiency. In the first idle test, coolant temperature within the modified cooling configuration reached the optimum coolant temperature of 60 °C about 41.28% faster when compared to baseline configuration. The modified configuration also heat up the transmission oil around 4 times faster. In the second NEDC test which simulates the real time driving condition, the coolant of the modified vehicle reached the optimum temperature around 28.26% compared to the baseline.

The effect of particle size on the dispersion and wear protection ability of MoS2 particles in polyalphaolefin and trimethylolpropane ester

The effect of particle size and surfactant on dispersion stability and wear protection ability was experimentally evaluated for polyalphaolefin (PAO 10) and bio-based base oil (palm trimethylolpropane ester) added with molybdenum disulfide (MoS2) particles. Nanolubricants were developed by adding 1u2009wt% of MoS2 particles that varied in size. In addition to the variation in particle size, an anionic surfactant was also used to analyze its interaction with both types of nanoparticles for stable suspensions and for the related effects on the antiwear characteristics. The wear protection characteristics of the formulations were evaluated by four-ball extreme pressure tests and piston ring on cylinder sliding wear tests. The wear surfaces were analyzed by scanning electron microscopy along with an energy-dispersive X-ray and an atomic force microscopy. The MoS2 nanoparticles with a nominal size of 20u2009nm exhibited a better load-carrying capacity, while better sliding wear protection was provided by nanoparticles with a nominal size of 50u2009nm.

Antiwear Behavior of CuO Nanoparticles as Additive in Bio-Based Lubricant

This work presents and discusses the anitwear characteristics of surface modified CuO nanoparticle suspensions in bio-based lubricant. 1.0 wt% unmodified as well as surface modified CuO nanoparticles (nominal size of 50 nm), were dispersed in base oil using an ultrasonic probe. Wear protection was evaluated by using Four-Ball Extreme Pressure (EP) testing and sliding wear tests. The scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analysis of the worn surface shows that: surface modification helped to improve the dispersion stability of CuO nanoparticles and related suspension show high EP characteristics in terms of load wear index and low cylinder liner wear due to surface mending effect of nanoparticles.