Nanoparticles (NPs) additives have gained notable influence in technology advancements owing to their excellent physiochemical properties with enhanced performance in application compared to previously used additives. The field of tribology has contributed significantly towards upgrading the overall engine efficiency through use of lubricating materials. The outstanding technique in achieving this is through adoption of additives derived from nanotechnology capable of preventing friction and wears during engine operations. Since only base oil cannot withstand most of the operating conditions, suitable additives are formulated and blended as to enhance the tribological properties. According to some research, nanoparticle additions have a greater impact on lubricant improvement. The ability to design NPs additives with unique qualities raises the value and demand for such class of products. The purpose of this study is to highlight the promising properties of NPs additives, mechanisms and to define the specific knowledge gaps related to the size of NPs towards friction and wear reduction. The function and mechanism performance of NPs additives during operation, such as mending, rolling, film formation, and polishing effect, is determined by their types. The excellent load carrying capability of nanoparticles during lubrication reflects their outstanding performance. The review presents an overview of the history and classifications of NPs and concisely elucidate their tribological effect when applied in lubrication. Excellent function of nano additives is the attribute of its nanoscale (1 to 100 nm) nature, thus categorized base on their size, shape, origin and composition. Certain expected characteristics of lubricating oil like friction and wear resistance, surfactant operation, load carrying capacity, extreme pressure operation, etc. were achieved through inclusion of nanoparticles additives.
The tribological enhancement of base lubricant under different concentration of formulated Eichhornia Crassipes carbon nanotubes (EC-CNTs) was conducted in this research. Cyclic heating approach was adopted in the formulation of EC-CNT and scientifically characterized. The characterization results confirmed the sample EC-CNTs. The effect of EC-CNT in base rapeseed oil terms of concentration, coefficient of friction (COF) and surface roughness (Ra), load carrying capacity, lubrication film stability and film mechanism were evaluated using high frequency reciprocating rig machine. The results showed that inclusion of EC-CNTs into base rapeseed oil, enhanced the tribological properties. The resultant values of COF were 0.064, 0.051 and 0.087 for rapeseed blended 1 mass%, 2.5 mass%, 4 mass% EC-CNT respectively. This is 38.5% COF reduction from 2.5 mass% EC-CNT against base oil. Under wear scar diameter, 2.5 mass% showed 47.9% reduction compared to base oil. The Ra was reduced with addition of nanoparticles, especially with 2.5 mass%. The tribological enhancement by EC-CNT is attributed from tribo-chemical reaction between the particles and the interfaces leading to formation of active protective tribo-film. The mechanism exhibited by the nanoparticles were healing and rolling from which the tribo-enhancement were achieved.
Surge and stall are the two main types of instabilities that often occur on the compressor system of gas turbines. The effect of this instability often leads to excessive vibration due to the back pressure imposed to the system by this phenomenon. In this work, fouling was observed as the major cause of the compressor instability. A step to analyze how this phenomenon can be controlled with the continuous examination of the vibration amplitude using a computer approach led to the execution of this work. The forces resulting to vibration in the system is usually external to it. This external force is aerodynamic and the effect was modeled using force damped vibration analysis. A gas turbine plant on industrial duty for electricity generation was used to actualize this research. The data for amplitude of vibration varied between -15 and 15 mm/s while the given mass flow rate and pressure ratio were determined as falling between 6.1 to 6.8 kg/s and 9.3 to 9.6 respectively. A computer program named VICOMS written in C++ programming language was developed. The results show that the machine should not be run beyond 14.0 mm vibration amplitude in order to avoid surge, stall and other flow-induced catastrophic breakdown
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