Syahrullail Samion

Simulation of forced convection in a channel with nanofluid by the lattice Boltzmann method

This paper presents a numerical study of the thermal performance of fins mounted on the bottom wall of a horizontal channel and cooled with either pure water or an Al2O3-water nanofluid. The bottom wall of the channel is heated at a constant temperature and cooled by mixed convection of laminar flow at a relatively low temperature. The results of the numerical simulation indicate that the heat transfer rate of fins is significantly affected by the Reynolds number (Re) and the thermal conductivity of the fins. The influence of the solid volume fraction on the increase of heat transfer is more noticeable at higher values of the Re.

Tribological Effects of Vegetable Oil as Alternative Lubricant: A Pin-on-Disk Tribometer and Wear Study

ABSTRACT The investigation of lubricated friction and wear is an extended study. The aim of this study is to investigate the friction and wear characteristics of double fractionated palm oil (DFPO) as a biolubricant using a pin-on-disk tribotester under loads of 50 and 100 N with rotating speeds of 1, 2, 3, 4, and 5 ms−1 in a 1-h operation time. In this study, hydraulic oil and engine oil (SAE 40) were used as reference base lubricants. The experiment was conducted using aluminum pins and an SKD 11(alloy tool steel) disc lubricated with test lubricants. To investigate the wear and friction behavior, images of the worn surface were taken by optical microscopy. From the experimental results, the coefficient of friction (COF) rose when the sliding speed and load were high. In addition, the wear rate for a load of 100 N for all lubricants was almost always higher compared to lubricant with a load of 50 N. The results of this experiment reveal that the palm oil lubricant can be used as a lubricating oil, which would help to reduce the global demand for petroleum-based lubricants substantially.

Effect of Addition of Tertiary-Butyl Hydroquinone into Palm Oil to Reduce Wear and Friction Using Four-Ball Tribotester

ABSTRACT Replacing mineral oil with vegetable oils as lubricants continues to attract interest due to their environmentally friendly characteristics and ease of disposal. However, one disadvantage can be low thermal oxidative stability. The purpose of our research is to investigate the ways in which oxidation can be contained by combining palm oil with a phenolic antioxidant. A homogeneous mix of palm oil and tertiary-butyl hydroquinone was found to exhibit satisfactory antioxidant properties and reduce wear and friction. Superior mineral engine oil was used to benchmark the performance.

Experimental Evaluation on Lubricity of RBD Palm Olein Using Fourball Tribotester

Tribology is defined as “the science and technology of surface interacting in motion” . Thus it is important for us to understand the surface interaction when they are loaded together as to understand the tribology process occurring in the system. The physical, chemical and mechanical properties not only cause the effects to the surface material in tribology behavior but also the near surface material. Apart from that, on the surface of the bulk material, lies a layer formed as a result from the manufacturing process. This deformed layer is covered by a compound layer resulting of chemical reaction of metal with the environmental substance such as air. In addition, the machining process such as cutting lubricants to be trapped may also cause the deformed regions of the surface. The regions on the surface material can critically affect both friction and wear of metals. In addition, the forces which arise from the contact of solid bodies in relative motion also affect both friction and wear. Thus, it is important for us to understand the mechanics contact of solid bodies in order to evaluate the friction and wear on solid bodies. Solid bodies are subjected to an increasing load deform elastically until the stress reaches a limit or maximum yield stress then deform plastically (Gohar and Rahnejat, 2008). Friction is known as resistance to motion. Friction can be categorized into five types; which are dry friction, fluid friction, lubricated friction, skin friction and internal friction. The friction forces are divided into two types; static friction force which is required to initiate sliding, and kinetic friction force which is required to maintain sliding. Coefficient of friction is known as the constant of proportionality in which the typical two materials may be similar or dissimilar, sliding against each other under a given set of surfaces and environmental conditions (Arnell and Davies, 1991). The first laboratory test device for determining lubricant quality was known as fourball tribotester is proposed by Boerlage in the year of 1993 (Ivan, 1980). The concept of friction for this machine is three stationary balls pressed against a rotating ball. The quality and the characteristics of the lubricant were established by the size of the wear scar or the seizure load and the value of friction obtained. The main elements of fourball machine are vertical driving shaft which hold the moving ball at the lower end with conical devices. Besides that,

A New Tribological Approach for Lubricated Sliding Contact of Pitted Metallic Curvature Cup

ABSTRACT Interest in the development and application of plant-based lubricants for medical use is increasing. This study investigates palm oil lubricants as environmentally friendly and renewable resources to optimize the motion in an ergonomic simulated metal hip prosthesis with modification to the acetabular cup surface. Although metal hip replacements are extensively used, minimizing metal-on-metal friction and wear using safe lubricants requires further investigation. The main physical properties of palm kernel oil and palm fatty acid distillate are considered. The viscosity, wear scar, and coefficient of friction are compared to hyaluronic acid. A modified pin-on-disc tribometer simulates friction and wear on a 28-mm-diameter acetabular cup and microscopy image analysis is used to examine the wear scar. The physical properties of palm oil derivatives reduce friction and wear. In brief, the most significant results of this study include the effect of lubricant and number of pits on wear and friction coefficient. The contribution of this research work is to maintain stability and increase the lifetime of ergonomic metal hip implants.

The Influence of Temperature in Wear Resistance Characteristic of Palm Fatty Acid Distillate

Palm fatty acid distillate (PFAD) has potential to be used as a lubricant. PFAD is a by-product from palm oil refinery, and it is classified as non-edible oil. However, vegetable oil has poor thermal performance and high oxidation rate. In this paper, the tribological performance of PFAD in different working temperature was investigated by using four-ball tribotester. Tests were conducted at temperatures 50oC, 75oC, 100oC and 125oC, under a normal load of 40 kg for one (1) hour. The rotational speed was set at 1200rpm. Similar tests were conducted using industrial hydraulic oil as a comparison lubricant. Analyses were focused on the coefficient of friction (CoF), wear scar diameter (WSD) and worn surface observation. Results show that coefficient of friction and wear were increased with the increment of temperature. However, palm fatty acid distillate show a better performance in term of friction reduction compared to industrial hydraulic oil.

Wear Behaviour of Palm Olein at Different Operating Temperature

One of the main disadvantages of vegetable oil as an industrial lubricant is its poor performance at high temperature. In this experimental work, the performance of refined, bleached and deodorized (RBD) palm olein was tested at different operating temperatures using four-ball tribometer, following the procedure of ASTM D 4172. The result produced by RBD palm olein was compared with the result by additive free paraffinic mineral oil. The result showed that the RBD palm olein had lower coefficient of friction compared to the paraffinic mineral oil. However, the wear scars on the ball bearings surface lubricated with RBD palm olein were larger compared to those lubricated with paraffinic mineral oil.

Lattice Boltzmann Numerical Approach to Predict Macroscale Thermal Fluid Flow Problem

Flow in an enclosure driven by buoyancy force is a fundamental problem in fluid mechanics. This type of flow is encountered in certain engineering applications within electronic cooling technologies, in everyday situation such as roof ventilation or in academic research where it may be used as a benchmark problem for testing newly developed numerical methods. A classic example is the case where the flow is induced by differentially heated walls of the cavity boundaries. Two vertical walls with constant hot and cold temperature is the most well defined geometry and was studied extensively in the literature. A comprehensive review was presented by Davis (1983). Other examples are the work by Azwadi and Tanahashi (2006) and Tric (2000). The analysis of flow and heat transfer in a differentially heated side walls was extended to the inclusion of the inclination of the enclosure to the direction of gravity by Rasoul and Prinos (1997). This study performed numerical investigations in two-dimensional thermal fluid flows which are induced by the buoyancy force when the two facing sides of the cavity are heated to different temperatures. The cavity was inclined at angles from 20° to 160°, Rayleigh numbers from 103 to 106 and Prandtl numbers from 0.02 to 4000. Their results indicated that the mean and local heat flux at the hot wall were significantly depend on the inclination angle. They also found that this dependence becomes stronger for the inclination angle greater than 90°. Hart (1971) performed a theoretical and experimental study of thermal fluid flow in a rectangular cavity at small aspect ratio and investigated the stability of the flow inside the system. Ozoe et al. (1974) conducted numerical analysis using finite different method of two-dimensional natural circulation in four types of rectangular cavity at inclination angles from 0° to 180°. Kuyper et al. (1993) provided a wide range of numerical predictions of flow in an inclined square cavity, covered from laminar to turbulent regions of the flow behavior. They applied k e turbulence model and performed detailed analysis for Rayleigh numbers of 106 to 1010. A thorough search of the literature has revealed that no work has been reported for free convection in an inclined square cavity with Neumann typed of boundary conditions. The type of boundary condition applied on the bottom and top boundaries of the cavity strongly affects the heat transfer mechanism in the system (Azwadi et al., 2010). Therefore, it is the purpose of present study to investigate the fluid flow behaviour and heat transfer mechanism in an inclined square cavity, differentially heated sidewalls and perfectly conducting boundary condition for top and bottom walls.