SiO2 Nanolubricants Research Articles

TiO2, CNTs, and SiO2 nanolubricant: An approach to improving the efficiency of a domestic refrigerator

To enhance a home refrigerator’s refrigeration system’s performance, three types of nanoparticles (TiO2, CNTs, and SiO2) were used to produce nanolubricants. The experiments were conducted with different charges of 50 and 60 g for R600a refrigerants, which a digital charging scale was used to measure. The inlet and exit temperature of the system’s components were measured using K-type thermocouples. The system was outfitted with two pressure gauges for measuring the pressures at suction and discharge. The obtained results show the system’s COP increases with nanolubricant-enhanced refrigerants, with the power of the based lubricant, TiO2, CNTs, and SiO2 nanolubricant being 0.0821, 0.0612, 0.0673, and 0.0702 kW, respectively. Therefore, nano-enhanced refrigerant can successfully replace R600a in the based lubricant in domestic refrigerators.

Assessment of TiO2, Al2O3, and SiO2 nanolubricant with eco-friendly refrigerant as substitute for R134a in a vapour compression system: An experimental approach

The efficiency of R600a, an eco-friendly refrigerant with TiO2, Al2O3, and SiO2 nanolubricants, was investigated and evaluated as a substitute for R134a in a vapour compression refrigerator system. Pressure gauges and K-type thermocouples were used to monitor the temperature and pressure. The power consumption of the refrigerator was observed using the digital wattmeter. Using NIST refprop version 9.0, the refrigerant's enthalpy was determined. The results showed that R600a with nanolubricant TiO2, Al2O3, and SiO2 had lower evaporator temperatures and pull-down times than R134a and pure R600a. For R600a in the based lubricant, TiO2, Al2O3, and SiO2 nanolubricant concentrations in the system, respectively, evaporator temperatures of − 5, − 10, − 7, and − 11 °C were attained after 210, 210, 240, and 240 min of pull-down time. TiO2, Al2O3, and SiO2 nanolubricants increased R600a cooling capacity by 9.7%, 0.5%, and 12.2%, respectively, while lowering power consumption by 23.3%, 17.5%, and 20.2%. R600a/nano mixtures can therefore replace R134a and R600a with pure lubricant in a household refrigerator system.

Tribological Analysis and Operation Issues of SiO<sub>2</sub> Nanolubricants for MQL Machining Operations

Minimum Quantity Lubrication (MQL) has been proved to be an efficient lubricant technique in machining that increases tool life, improves surface roughness, facilitates the recycling of the resulting chips, brings more sustainable practices in terms of minimum use of lubricants, and reduces the operators’ exposures to toxic particles with respect to conventional cooling practices. In order to increase the performance of MQL, nanoparticles of Al2O3, MoS2, SiO2 graphite and graphene among others have been recently introduced into MQL lubricants. This new approach, called nanoMinimum Quantity Lubrication (NMQL), has been proved to provide better thermal conductivity and lower friction coefficients during cutting, which in turns means higher cutting tool life and lower cutting forces. In this paper, a stable SiO2 -based nanolubricant was produced and characterized. A tribological analysis was conducted on SiO2 nanolubricants to be used on MQL operations. Operational issues related to particles deposition along time, loss of nanolubricant properties when it comes from the MQL system and mist generation were also analyzed.

Molecular dynamics simulation on engine oil nanolubricant boundary lubrication conditions

AbstractThe employment of nanoparticle additives in engine oil provides an effective technique for improvement in engine performance and emission. In this study, graphene, graphene–MWCNT, and graphene–SiO2 hybrid nanoparticles have been dispersed in engine oil (n‐decane) to measure the effects of microscopic characteristics of interfacial layer between the carbon–carbon, carbon–hydrogen, carbon–oxygen, and hydrogen–oxygen molecules under fixed shear rate 600 s−1. The boundary lubrication conditions are depicted with nanoindentation operation, in which interaction between the atoms generates the molecular forces under indentation and scratching operation that provide the nucleation and propagation of dislocation in the planes. The result shows that in an early stage of nanoindentation, plastic deformation occurs in the lubricant substrate around the indenter. Furthermore, forces generated in the z‐direction have a significant effect as compared with the forces x‐ and y‐directions. Nanoindentation results concluded that for graphene–MWCNT/engine oil (n‐decane) nanoparticles, at a volume fraction of 1.8%, the nanoparticles outperformed all other nanolubricants. At a volume fraction of 0.3%, the adhesion between the solid and liquid interface was increased by 2.5% graphene nanolubricant, 4% graphene–MWCNT nanolubricant, and 8% graphene–SiO2 nanolubricant. At 1.8% volume fraction, 240% increase in graphene–MWCNT nanolubricant, 72% increase in graphene nanolubricant, and 20% increase in graphene–SiO2 nanolubricant. This trend indicates that the performance of graphene SiO2 nanolubricants is superior at low‐volume fractions, whereas the performance of graphene nanolubricants and graphene–MWCNT nanolubricants is superior at high‐volume fractions. Also we observed the scratching effect of indenter on nanolubricants.

Comparative air conditioning performance using SiO2 and Al2O3 nanolubricants operating with Hydrofluoroolefin-1234yf refrigerant

• Performance using SiO 2 and Al 2 O 3 Nanolubricants with Hydrofluoroolefin-1234yf. • Experiments are undertaken for different nanolubricants up to 0.05% concentration. • Cooling capacity of SiO 2 nanolubricant at 0.01% concentration improved up to 15.7% • Performance of Al 2 O 3 nanolubricant increased up to 9.8% at 0.05% concentration. • Type of nanolubricant contributed to variation parameter improvement of the system. Nowadays, the automotive air-conditioning system operating with Hydrofluoroolefin-1234yf or R1234yf refrigerant is used to reduce the global warming potential. This study aims to investigate the performance of SiO 2 and Al 2 O 3 nanolubricants with R1234yf refrigerant in the automotive air conditioning system. The polyalkylene glycol-based nanolubricant was prepared using a two-step preparation method, and the stability of the nanolubricant was assessed using visual sedimentation observation and zeta potential analysis. The experimental investigation on the performance of automotive air conditioning system with R1234yf was undertaken for the SiO 2 and Al 2 O 3 nanolubricants at different volume concentrations and various operating conditions. The system with SiO 2 nanolubricant at 0.01% volume concentration demonstrated the best cooling capacity performance with an average enhancement of 15.7%. On the other hand, the highest coefficient of performance increment and power consumption reduction were attained up to 9.8% and 27.1%, respectively for Al 2 O 3 nanolubricant at 0.05% volume concentration. The SiO 2 nanolubricant performed with better cooling capacity, higher power consumption and lower coefficient of performance than the polyalkylene glycol-based lubricant. In contrast, the Al 2 O 3 nanolubricant improved the coefficient of performance and reduced the power consumption. Since both nanolubricants provide their respective advantages, more research into integrating the two nanoparticles for refrigeration systems with R1234yf refrigerant is encouraged.

Procena R600a pomešanog sa različitim količinama nanočestica CuO, Al2O3 i SiO2

In this work three different nanoparticle concentrations of CuO, Al2O3, and SiO2 are dispersed in R600a vapour compression refrigeration system. The experiment was carried out using nanolubricant concentrations of 0g/L, 0.2g/L, and 0.4g/L having CuO, Al2O3, and SiO2 nanoparticles diffused in mineral oil with refrigerant mass fractions of 30, 40, and 60g. Nano lubricant was prepared at various concentrations using CuO, Al2O3, and SiO2 nanoparticles and refrigerant mass charges which were employed to perform tests. The system's performance was investigated with the variables such as coefficient of performance, refrigeration effect, compressor work, and pull down test. As a result of this study, it can be inferred that there is a significant enhancement in COP value of 2.7 by utilizing 0.4g/L SiO2 nanolubricant concentration with 40g of refrigerant. This inclusion of nanolubricant enhanced the refrigeration effect up to180W and resulted in a reduction of compressor work to 60W.The results obtained by using nanolubricants are compared with the system without nanolubricants. The pull down test with 0.4g/L SiO2 nanolubricant concentration quickly achieved low evaporator temperature compared to other conditions. The research was performed with various nanoparticles in R600a refrigeration system, the experiments were conducted with different nanoparticles by varying nanoparticle concentrations and refrigerant mass charges. From the experiments it is observed that SiO2 nanolubricant results in enhanced COP and refrigerant effect,which can be used as a better alternative to a pure mineral refrigeration system. Among three nanoparticles, SiO2 resulted in better performance and refrigerating effect with 56% less power consumption.

Experimental investigation of Sio2 nanolubricants for R410A vapour compression refrigeration system

Abstract In this paper Sio2 nanoparticles is dispersed in lubricating oil of R410A refrigeration system. Experimental investigation was carried using 0 g/L, 0.2 g/L, 0.4 g/L and 0.6 g/L of Silicon dioxide (Sio2) nano particle concentrations in Polyolester (POE) lubricating oil by varying the mass of refrigerant R410A as 30, 40, 50, 60 and 70 g. The performance of the refrigeration system was investigated using the important parameters like Coefficient of performance, refrigerating effect and compressor work and pull down test. From the experiment it has been concluded that 0.4 g/L Sio2 nano-lubricant and 40 g refrigerant mass gave more refrigerating effect and it was found to be 160 W when compared with system without nanolubricants and with 0.2 g/L and 0.6 g/L nanolubricant with various refrigerant mass charges. Addition of Sio2 nanolubricants results in reduced compressor work of 80 W with 0.4 g/L and 40 g of refrigerant. Dispersion of Sio2 nanolubricants leads to enhanced C.O.P value of 1.7 for 0.4 g/L nanolubricants when compared to system without nanolubricants and with 0 g/L, 0.2 g/L and 0.6 g/L nanolubricants. From the pull down test, the obtained evaporator temperature is reduced very quickly while using 0.4 g/L nanolubricants with 40 and 60 g refrigerant mass charges.

Effects of electroosmotic additives on capillary penetration of lubricants at steel/steel and steel/ceramic friction interfaces

To understand the electroosmosis effect of lubricants at friction interfaces, the tribological characteristics of aqueous lubricants and SiO2 nanolubricants containing an electroosmotic promoter, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS), and an electroosmotic suppressant, cetyltrimethylammonium bromide (CTAB), were examined using a four-ball tribometer. The results show that CHAPS lubricants produce reductions in the friction coefficient and wear scar diameter, whereas CTAB lubricants exhibit the opposite behavior. The variation in tribological performance under a steel/ceramic contact is more significant than that under a steel/steel contact. A worn surface analysis indicates that a SiO2-based tribofilm is formed with CHAPS nanolubricants, whereas the tribofilm is hardly observed with CTAB nanolubricants. This is attributed to the capillary electroosmosis effect induced by the self-excited electric field formed at friction interfaces, which affects the penetrability of lubricants.

Evaluation of the properties of POE/SiO2 nanolubricant for an energy-efficient refrigeration system – An experimental assessment

An experimental evaluation on the Thermal, Rheological, Tribological, Corrosion, oxidative stability, eco-friendliness properties of Polyol Ester (POE) oil suspended with SiO2 nanoparticles has been carried out for establishing its suitability to use as nanolubricant in refrigerant compressors. The mass fractions and temperatures considered are from 0.01 to 0.2% and 25 to 100 °C. The Thermal conductivity, Viscosity, Viscosity Index, and Flashpoint enhanced with the increase in SiO2 proportions. The oxidative stability was slightly affected while no effect was observed in the corrosive characteristics. The 0.15% SiO2 nanolubricant was having least CoF and surface roughness. The acid and saponification value slightly increased due to the addition of nanoparticles. All the nanolubricants were a little toxic and biodegradable. Hence, extended life and cool operation of refrigerant compressors are expected using POE oil with up to 0.15% SiO2 due to the enhanced thermal, rheological & non-corrosive properties, and improved tribological characteristics.

Performance of a hydrocarbon driven domestic refrigerator based on varying concentration of SiO2 nano-lubricant

This experimental work studies the performance of varying concentrations of SiO2 nanoparticle in mineral oil lubricant using LPG refrigerant, as a retrofit to R134a in a domestic refrigeration system. The test rig is fitted with thermocouple K, pressure gauges and a watt-meter to monitor the suction, discharge, the condensing temperatures, pressures and power consumption in accordance with ISO 8187 recommendations. Performance parameters investigated included: pull down time, compressor power consumption and input, coefficient of performance and thermal conductivity and viscosity. Findings showed that all the selected charges of LPG refrigerant infused with varying concentrations of nano-lubricants, achieved equal values of -3 °C (ISO 8187), or lower values of evaporator air temperatures at lower refrigerant charges, than the baseline R134a refrigerant. All the selected nano-lubricants based refrigerants resulted in improved Coefficient of Performance (COP) than R134a refrigerant, with COP values ranging from 2.05 with 50 g charge of LPG using 0.4 g/L nano-lubricant to 2.65 with 60 g of LPG using 0.2 g/L SiO2 based lubricant. Lower power input was recorded by the compressor for all the selected charges of SiO2-lubricant based LPG than R134a refrigerants, having 28.81 W (with 60 g charge of LPG using 0.2 g/L) and 39.21 W (with 100 g charge of R134a refrigerant using pure compressor oil lubricant). In addition, at low concentration of nanoparticle in the lubricants based LPG refrigerant, reduction in power consumption of the compressor was observed, whereas higher concentration of nanoparticle in the lubricant, resulted in a rise in power consumption. Furthermore, thermal conductivity values were found to be low at the suction and discharge ends of the compressor for R134a using pure mineral oil lubricant, whereas the values were high for retrofit working fluid (pure LPG refrigerant, and LPG with varying concentrations of nano-lubricants), at the suction and discharge ends of the compressor.

Experimental investigation of TiO2-, SiO2- and Al2O3-lubricants for a domestic refrigerator system using LPG as working fluid

This paper experimentally investigated low concentration of TiO2, SiO2 and Al2O3 nanoparticles dispersed in a mineral oil lubricant, in a domestic refrigerator system, using LPG as the working fluid. The performance of the system was investigated with test parameters including: power consumption, thermal conductivity and viscosity at the suction and discharge end of the compressor, evaporator air temperature (pull-down time) was also considered. Findings showed that all nano-lubricant based LPG had lower steady state evaporator air temperatures than LPG with pure mineral oil at 180min. In addition, TiO2 and SiO2 nano-lubricants gave 13 and 12% reductions in power consumptions than the base refrigerant (LPG), whereas higher power consumption of the refrigerator system was found with utilization of Al2O3-lubricant when compared with base refrigerant (LPG). Futhermore, error analysis conducted using Mean Absolute Bias Error (MAPE) and Root Mean Square Error (RMSE) showed that Al2O3-lubricant gave the best fit with pure-lubricant LPG than TiO2 and SiO2. Application of nanoparticles in refrigeration systems was found to improve the performances of the system, but TiO2 followed by SiO2 will be prefered among the nanoparticles, as Al2O3-lubricant was found to be incompartible with hydrocarbon refrigerant having led to a high power consumption.

Comparative study of thermo-physical properties of SiO2 and Al2O3 nanoparticles dispersed in PAG lubricant

Currently, the possibility to enhance fuel efficiency with cutting edge advancements is thoroughly investigated by researchers. One of the best ways to increase the fuel efficiency is by improving the performance of the automobile air conditioning system. As a result, nanoparticles are dispersed in the lubricants of automobile air conditioning compressor for heat transfer and tribology enhancement. In this paper, viscosity and thermal conductivity of the SiO2 nanoparticles dispersed in Polyalkylene glycol (PAG) lubricants for 0.2–1.5% volume concentrations and 303–353K working temperatures was investigated and compared with Al2O3 nanolubricant. The viscosity and thermal conductivity of the nanolubricants increased with volume concentration but decreased with temperature. The paper proposed correlations for viscosity and thermal conductivity of SiO2 nanolubricants at various concentrations and temperatures. The allowable volume concentration of SiO2 and Al2O3 nanolubricants for application in automobile air conditioning compressors are up to 1.0% and 0.3%, respectively. The thermal conductivity of SiO2 nanolubricants at 1.0% concentration is higher than Al2O3 nanolubricants at 0.3% allowable concentration. As a conclusion, it is advisable to use the SiO2 nanolubricants with volume concentration of less than 1.0% for applications in automotive air conditioning system.

Lubrication performance of MoS2 and SiO2 nanoparticles as lubricant additives in magnesium alloy-steel contacts

The effects of the base lubricant with and without nanoparticles on the tribological behavior of magnesium alloy/steel contacts were investigated using a reciprocating sliding ball-on-flat tribometer. Three sets of contact conditions were used to evaluate the effect of concentration, the capacity of carrying load and the stability of the lubrication film, respectively. The results showed that the tribological properties of the base lubricant have been improved by adding the nanoparticles. As compared with the SiO2 nanolubricants, the positive effect of the MoS2 nanolubricants is more pronounced in terms of the load carrying capacity and the lubrication film stability. Mechanisms by which the nanolubricants improve tribological behaviors are discussed.

Effect of SiO2 nanoparticles as lubricating oil additives on the cold-rolling of AZ31 magnesium alloy sheet

Magnesium alloy sheets were processed by cold rolling without lubrication and with SiO2 nanolubricant so as to investigate cold rolling performance by measuring rolling force as well as the surface roughness of the sheets. A series of ball on disc tests without lubrication and with SiO2 nanolubricant conditions were carried out to simulate the contact and sliding during the cold rolling process. The results indicate that the SiO2 nanolubricant effectively reduced the rolling force and improved the surface quality of sheets by SiO2 nanolubricant during cold rolling process. The excellent cold-rolling performances of AZ31 Mg alloy with SiO2 nanolubricant were attributed to the friction-reducing and the anti-friction mechanism was based on the deposition of nanoparticles on the magnesium alloy surfaces.

Novel uses of SiO2 nano-lubrication system in hard turning process of hardened steel AISI4140 for less tool wear, surface roughness and oil consumption

Abstract Hardened steel AISI 4140 material is commonly used to produce automotive parts such as shafts, gears and bearings. Machining this material significantly increases the temperature in the cutting zone and is critical in deciding workpiece quality. Though cutting fluids are widely employed to dissipate the heat in machining, they threaten the ecology and health of workers. Hence, there arises a need to identify eco-friendly and user-friendly alternatives to conventional cutting fluids. Modern tribology has facilitated the use of a nano-lubrication system. For this purpose, a novel uses of nano-lubricants in minimum quantity lubrication (MQL) system were studied. In the present work, a mist of SiO2 nano-lubrication was used and applied by air pressure in turning of hardened steel AISI4140. In this research work, the optimum SiO2 nano-lubrication parameters to achieve correct lubrication conditions for the lowest tool wear and best surface quality were investigated. These parameters include nano-lubricant concentration, nozzle angle and air carrier pressure. The Taguchi optimization method is used with standard orthogonal array L16(4)3. This research is investigating on the new and novel uses of SiO2 nano-lubricant by conducting analysis on tool wear and surface roughness using fuzzy logic and response analysis to determine which process parameters are statistically significant. Besides, these analyses were conducted in order to prove the effectiveness of nano-lubricant. Finally, confirmation tests were carried out to investigate optimization improvements.

Investigation on the morphology of the machined surface in end milling of aerospace AL6061-T6 for novel uses of SiO2 nanolubrication system

Abstract Aluminium 6061-T6 alloy is commonly used in the aircraft and automotive industries for its superior mechanical properties. To improve machining performance such as tool life and workpiece surface finish, lubricant oil is normally introduced into the cutting zone during the machining process. However, at higher temperature and pressure in heavy industry machining, the ordinary oil lubricant has no function as it is usually evaporated. Introducing SiO2 nanolubricant in the cutting zone could withstand this severe conditions and the rolling action of billions of nanoparticles in the tool chip interface produces much less friction and thermal deformation leading to superior surface quality. Using nanolubrication in machining could also minimize the consumption of lubrication oil; consequently, less pollution will be caused. To ensure workpiece surface quality, a morphological analysis of AL6061-T6 after machining with SiO2 nanolubricant is investigated at different nanolubricant concentration using Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray (XRD) machines. From the results and analysis, the increment of nanolubricant concentration at 0.2% would increase the growth of thin protective film on machined surfaces due to the breaking process from the rolling action of billions of nanoparticle between the tool-chip interfaces. These formations of the thin film on the machined surface could improve the machining performance by reducing the cutting force, reduce the cutting temperature and improves the surface quality.