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The paper aims to monitor the condition of heavy Earth-moving machines (HEMMs) used in open cast mines by lube oil analysis.

Oil samples at periodic interval were collected from the HEMM engine (Model No: BEML BH50M). Ferrography and Field Emission Scanning Electron Microscopy have been used for the wear particle analysis present in oil samples. Viscosity analysis and Fourier transform infrared spectroscopy have been done to investigate the degradation in quality and changes as compared to the initial structural properties of the lubricants.

The results obtained indicates wear in cylinder liner and piston ring. Copper, cast iron, alloy steel and ferrous oxide have been found as rubbing wear particles and cutting wear particles. Contamination level has also been found to be increasing in consecutive older oil samples. Chemical properties degraded with usage time and variations in oxidation and soot level have also been observed in every sample.

The results will be very much useful to maintenance teams of mining industry for early prediction of any impending failure of the machines, for example, diesel dilution, severe wear of the piston or cylinder liner leading to seizure can be predicted.

The HEMMs are an important piece of equipment in coal mining. Proper condition monitoring of HEMM is required to reduce the break down and down time to increase production.

The aim of this paper is to study the effect of deterministic roughness and small elastic deformation of surface on flow rates, load capacity and coefficient of friction in Rayleigh step bearing under thin film lubrication.

Reynolds equation, pressure-density relationship, pressure-viscosity relationship and film thickness equation are discretized using finite difference method. Progressive mesh densification (PMD) method is applied to solve the related equations iteratively.

The nature and shape of roughness play a significant role in pressure generation. It has been observed that square roughness dominates the pressure generation for all values of minimum film thickness. Deformation more than 100 nm in bounding surfaces influences the film formation and pressure distribution greatly. Divergent shapes of film thickness in step zone causes a delay of pressure growth and reduces the load capacity with decreasing film thickness. The optimum value of film thickness ratio and step ratios have been found out for the maximum load capacity and minimum coefficient of friction, which are notably influenced by elastic deformation of the surface.

It is expected that these findings will help in analysing the performance parameters of a Rayleigh step bearing under thin film lubrication more accurately. It will also help the designers, researchers and manufacturers of bearings.

Most of the previous studies have been limited to sinusoidal roughness and thick film lubrication in Rayleigh step bearing. Effect of small surface deformation due to generated pressure in thin film lubrication is significant, as it influences the performance parameters of the bearing. Different wave forms such as triangular, sawtooth, sinusoidal and square formed during finishing operations behaves differently in pressure generation. The analysis of combined effect of roughness and small surface deformation has been performed under thin film lubrication for Rayleigh step bearing using PMD as improved methods for direct iterative approach.

The present work aims to numerically investigate the natural convective heat transfer performance of aluminium oxide (Al₂O₃)-gear oil nanolubricant used in heavy earth moving machinery (HEMM).

Viscosity, density and thermal conductivity of nanolubricants have been experimentally determined. The numerical simulation has been performed by using computational fluid dynamics (CFD) for a cylinder cavity which resembles shape of automatic transmission system of HEMM. The left wall temperature has been maintained at 293 to 313 K, and right wall is at a constant temperature of 283 K. Due to absence of any experimental study on natural convective heat transfer performance of Al₂O₃-gear oil nanolubricant, initially CFD model has been tested for accuracy by comparing experimental, and CFD results for Al₂O₃-water nanofluid has been available in open literature.

It has been observed that Nusselt number increases with increase in Rayleigh number, but it decreases with increasing particle volume fraction. The gear oil-based nanolubricant is expected to have the better thermal performance in HEMM at higher temperature.

The numerical analysis will help to predict the thermal performance of nanolubricant. The outcome may help the designers, researchers and manufacturers of HEMM.

Most of the previous studies have been limited with base fluid as water, ethylene glycol, etc. in the field of nanofluid. CFD study for thermal performance of Al₂O₃-gear oil nanolubricant is essential before the experimental work. This work is the preliminary stage of application of, nanolubricant for heat transfer.

Artificial biomaterials are implanted to the human body to support the structure depending upon the extent of deformity or damage. This paper aims to formulate an experimental approach to assess the suitability of materials that can be used in the manufacture of human implants.

Five different pin materials such as SS304, Alumina, HDPE, UHMWPE and Brass have been chosen to be suitable for implants. The tribological properties of the aforementioned materials have been tested on a simple pin-on-disc apparatus. EN31 was chosen as the disc material because its hardness value is much higher than that of the pin materials used. The test materials were constructed in the form of spherical end pins to have point contacts and to reduce the depth of wear.

It has been observed that the polymeric (HDPE and UHMWPE) and ceramic materials (Alumina) are much better than the traditional metallic materials. The wear rate is very low for these materials owing to their self-lubricating properties.

The experimental studies will help predict the performance and life of implant materials in the human body.

In most cases, SS316L that possesses nickel compositions is used as the disc material; SS316L is toxic to the human body. In the present study, a high carbon alloy steel with high degrees of hardness EN31 is used as a disc counter-face material.

This study aims to present the experimental and computational performance analysis in compact plate heat exchanger (PHE) using graphene oxide nanofluids at different concentrations and flow rate.

Field emission scanning electron microscope and X-ray diffraction were used to characterize graphene oxide nanoparticles. The nanofluid samples were prepared by varying volume concentration. Zeta potential test was done to check stability of samples. The thermophysical properties of samples have been experimentally measured. The experimental setup of PHE with 60° chevron angle has also been developed. The numerical analysis is done using computational fluid dynamics (CFD) model having similar geometry as of the actual plate. Distilled water at fixed temperature and flow rate is used in hot side tank. Nanofluid at fixed temperature with varying concentration and flow rate is used in cold side tank as coolant.

The numerical and experimental results were compared and found that both results were in good agreement. The results showed ∼13% improvement in thermal conductivity, ∼14% heat transfer rate (HTR), ∼9% in effectiveness and ∼10% in overall heat transfer coefficient at cost of pressure drop and pumping power using nanofluid. Exergy loss also decreased using nanofluid at optimum concentration of 1 Vol.%.

The CFD model can be significant to analyze temperature, pressure and flow distribution in heat exchanger which is impossible otherwise. This study gives ease to predict PHE performance with high accuracy without performing the experiment.

The probability distribution of major length and aspect ratio (major length/minor length) of wear debris collected from gear oil used in planetary gear drive were analysed and modelled. The paper aims to find an appropriate probability distribution model to forecast the kind of wear particles at different running hour of the machine.

Used gear oil of the planetary gear box of a slab caster was drained out and charged with a fresh oil of grade (EP-460). Six chronological oil samples were collected at different time interval between 480 and 1,992 h of machine running. The oil samples were filtered to separate wear particles, and microscopic study of wear debris was carried out at 100X magnification. Statistical modelling of wear debris distribution was done using Weibull and exponential probability distribution model. A comparison was studied among actual, Weibull and exponential probability distribution of major length and aspect ratio of wear particles.

Distribution of major length of wear particle was found to be closer to the exponential probability density function, whereas Weibull probability density function fitted better to distribution of aspect ratio of wear particle.

The potential of the developed model can be used to analyse the distribution of major length and aspect ratio of wear debris present in planetary gear box of slab caster machine.

The study aims to use nanofluids as coolants for improving heat transfer peculiarities of plate heat exchangers (PHE). The experimental and numerical investigations are thoroughly performed using distilled water-based Al₂O₃, graphene nanoplatelet (GnP) and multi-walled carbon nanotubes (MWCNT) nanofluids.

The numerical simulation based on Single Phase Model (SPM) was performed on a realistic 3 D model of PHE having similar dimensions as of the actual plate. The standard k-epsilon turbulent model was used to solve the problem. The concentration and flow rate of nanofluids were ranging from 0.1 to 1 Vol.% and 1 to 5 lpm, respectively, at 30°C. Whereas, hot side fluid is distilled water at 2 lpm and 80°C. The heat transfer characteristics such as bulk cold outlet temperature, heat transfer rate (HTR), heat transfer coefficient (HTC), Nusselt number (Nu), pressure drop, pumping power, effectiveness and exergy loss were experimentally evaluated using nanofluids in a PHE.

The experimental results were then compared with the numerical model. The experimental results revealed maximum enhancement in an average heat transfer rate of 9.86, 14.86 and 17.27% using Al₂O₃, GnP and MWCNT nanofluids, respectively, at 1 Vol.%. The present computational fluid dynamics model accurately predicts HTR, and the results deviate <1.1% with experiments for all the cases. The temperature and flow distribution show promising results using nanofluids.

The study helps to visualise heat transfer and flow distribution in PHE using different nanofluids under different operating conditions.

Nanofluids exhibit enhanced heat transfer characteristics and are expected to be the future heat transfer fluids particularly the lubricants and transmission fluids used in heavy machinery. For studying the heat transfer behaviour of the nanofluids, precise values of their thermal conductivity are required. For predicting the correct value of thermal conductivity of a nanofluid, mathematical models are necessary. In this paper, the effective thermal conductivity of various nanofluids has been reported by using both experimental and mathematical modelling. The paper aims to discuss these issues.

Hamilton and Crosser equation was used for predicting the thermal conductivities of nanofluids, and the obtained values were compared with the experimental findings. Nanofluid studied in this paper are Al₂O₃ in base fluid water, Al₂O₃ in base fluid ethylene glycol, CuO in base fluid water, CuO in base fluid ethylene glycol, TiO₂ in base fluid ethylene glycol. In addition, studies have been made on nanofluids with CuO and Al₂O₃ in base fluid SAE 30 particularly for heavy machinery applications.

The study shows that increase in thermal conductivity of the nanofluid with particle concentration is in good agreement with that predicted by Hamilton and Crosser at typical lower concentrations.

It has been observed that deviation between experimental and theoretical results increases as the volume concentration of nanoparticles increases. Therefore, the mathematical model cannot be used for predicting thermal conductivity at high concentration values.

Studies on nanoparticles with a standard mineral oil as base fluid have not been considered extensively as per the previous literatures available.

The purpose of this paper is to experimentally investigate the effect of aluminium oxide (Al₂O₃) nanoparticles on gear oil (SAE EP 90) as a lubricant in heavy earth moving machinery (HEMM).

Particle size distribution, viscosity, density, stability and other rheological properties have been measured. The variations in rheological properties with varying nanoparticle volume fraction and temperature have been investigated at atmospheric pressure over a temperature range of 15-40°C. Classical as well as modified Krieger – Dougherty models have been used for finding out viscosity variation and a new empirical model has been presented.

Dynamic light scattering data confirm the presence of large agglomeration of about 5.5 times of primary nanoparticles in nanofluid. Nanofluid starts behaving as a non-Newtonian fluid with increasing nanoparticle volume fraction. Viscosity of nanofluid is enhanced by 1.7 times of base fluid with 2 per cent volume fraction of Al₂O₃ nanoparticles, while it significantly decreases with increase in temperature. The stability of nanofluid decreases with increase in nanoparticle volume fraction due to settling down of nanoparticles. It has also been observed that shear thinning increases with increasing nanoparticle volume fraction.

It is expected that these findings will contribute towards the improvement in rheological and thermal properties of the conventional lubricants used in HEMM. The outcome may help the designers, researchers and manufacturers of the HEMM.

Most of the previous research in this field is confined with base fluid as water, ethylene glycol, transformer oil, etc. Gear oil in HEMM performs under high mechanical and thermal load. The Al₂O₃/gear oil nanofluid is expected to have better cooling and lubrication properties.

The purpose of this paper is to explore the wear phenomena on the bottom surface of an excavator bucket and optimize the design parameters to reduce wear rate by converting sliding motion to rolling motion of rock during the time of operation.

A test rig has been developed to study the wear phenomena and type of wear on the excavator bucket. Three different bottom plates have been fabricated for experiments to observe the difference of severity of wear in terms of volume of material removal.

It has been observed that the bottom plate having the mesh-type wear bar pattern was comparatively more resistive to wear than the other two models. Wear-affected zone on the bottom plate was also detected and represented with the help of colour contour.

It is expected that these findings will contribute towards the development of the bottom plate of the excavator bucket with some new pattern of a wear bar, which will be efficient to reduce the phenomena on its surface.

The excavator is one of the important equipment in coal mining. A proper design of the excavator bucket will reduce the wear, as well as the running cost of equipment, and increase the rate of production.