Oil Sump Research Articles

Effects of Nano-Lubricants on Power and CO Emission of a Diesel Engine: An Experimental Investigation

In this study, it was aimed to investigate the effects of copper (II) oxide (CuO), copper zinc iron oxide (CuZnFe2O4) and copper iron oxide (CuFe2O4) nanoparticle additives in synthetic diesel engine oil (5W-40) at the fraction of 0.08 wt% on friction and wear in piston ring-cylinder liner mechanism of the engine. In this regard, Scanning Electron Microscope (SEM) analyses of the nanoparticles were first carried out and via a linear reciprocating tribometer, friction coefficients were determined on specimens comprised of the same material with real engine piston ring. Subsequently, SEM analyses of the samples exposed to abrasion were carried out to investigate the wear characteristics. In the second stage of the experimental study, oil sump of the diesel test engine was filled with raw oil (oil without nano additives) and prepared nano oils (oil+nano additives) separately to unravel the effects of the lubricants on engine power and carbon monoxide (CO) emissions. According to the results, it was determined that CuZnFe2O4 nano lubricant was the most pronounced of all in terms of tribological performance, engine power and CO emissions. The results depicted that, in the best case, an average increment of 15% in engine power and an average reduction of 18% in CO emissions with CuZnFe2O4 nano oil were provided compared to that of the raw oil.

Thermal analysis of oil sump and compression unit in a rotary compressor

Thermal analysis of the oil sump and compression unit in a hermetic rotary compressor is important for enhancing its performance and reliability. In this study, the temperature distribution, heat-transfer mechanism, and heat balance of the oil sump and compression unit in a rotary compressor were analyzed using the 3D computational fluid dynamics (CFD) fluid-solid coupled model. Considering the practical characteristics of the rotary compressor, some special treatments are proposed for the simulation model. Instead of using empirical formulations, heat-transfer coefficients in the upside of the main bearing and compressor shell were obtained using the 3D CFD simulation model; the dynamic process in the suction chamber and compression chamber was considered to be static and the oil film in the inner wall of the cylinder, rib effect of the A-frame structure at the bottom of the compressor shell, and friction loss in the side of the sliding vane were considered. The simulation results showed good agreement with experimental results. We expect that these analytical results would be of great use in further understanding the temperature distribution and heat-transfer mechanism of oil sumps and compression units and also provide guidelines for improving the performance and reliability of rotary compressors.

Experimental study on electronic expansion valve failure of a R290 room air conditioner during heating-defrosting process

As an alternative refrigerant for HCFCs, R290 has been gradually applied in commercial refrigerators and humidifiers because of its excellent environmental and thermodynamic properties. The application of R290 in room air conditioner (RAC) is still in the stage of promotion. Abnormal failure of throttle component in heating and defrosting process frequently occurred during developments of R290 RACs. In this paper, the mechanism of abnormal failure of electronic expansion valve (EEV) of a R290 RAC during heating-defrosting process was experimentally investigated in enthalpy-difference laboratory. The compressor and system pipeline were visualized and a viscometer was performed to measure the variation of viscosity in oil sump. The experimental results showed that the EEV failure in the startup stage of heating process, was caused by oil blockage. The oil blockage was mainly caused by much more oil and lower temperature at after-throttling during defrosting and heating-defrosting mode conversion process. The results and analysis of this research can provide an effective guidance for alleviating and eliminating the throttle component failure and improving the reliability of R290 RACs.

Performance and refrigerant mass distribution of a R290 split air conditioner with different lubricating oils

The charge mass of R290 in room air conditioners (RACs) is limited by relevant standards due to its flammability. Meanwhile, the selection of the lubricating oil for R290 RACs is not yet clear. Mineral oils (MOs) are used currently, but the system performance when using MO is constrained under the existing standards because of the high R290 solubility in compressor oil sump. Some polyalkylene glycol synthetic oils (PAGs) are less soluble with R290, but the use of PAG in R290 RACs is less studied. In this paper, the effects of different lubricating oils including a PAG and a MO on a 1.5 HP R290 split RAC were experimentally investigated under cooling and heating mode. The refrigerant mass distribution was measured at steady state by “Quick Closing Valve Technique”. The system performance and R290/oil mixture viscosity in oil sump were compared. Results showed that using the PAG could reduce the R290 mass in compressor by about 10–13 g and improve heating capacity by 1.8–2.3%, but the Coefficient of Performance (COP) was lower under heating mode due to the excessive R290/oil mixture viscosity in oil sump. Results also showed that the refrigerant mass in the liquid line accounted for about 15% of the total charge mass under heating mode, and only 4–8% under cooling mode. The results can provide guidance for the system design and selection of lubricating oil for R290 RACs.

Monitoring of Engine Lubrication using Acoustic Emission Technology

This research presents the application of Acoustic Emission (AE) sensor to explore the feasibility of an AE signal in the process of monitoring the engine oil viscosity on different condition of mileage during the engine operation. The viscosity experiment was performed in a prior stage of the experiment using four samples of SAE 5W-30 engine oil with the different condition of mileage. On the next occasion, the AE signal was acquired on three cylinders of a four-stroke gasoline engine with a cooling water system which operates using the previous lubricant sample. In this experiment, the AE sensor was bonded on the outside of the engine block and located at the oil filter and oil sump location. It was found that the AE energy value is capable of determining the variant of the engine oil viscosity. The results from this project show that via AE technology proved to be feasible for the development of a real-time lubricant condition monitoring which was believed to be a new technology in the automotive industry.

Experimental investigation and thermal analysis of coupler-rocker ball bearing

Ball bearings are widely used in many machineries and industrial applications. Thermal behaviour of oscillating ball bearings is unknown due to its complex pendulum-like motion and is discussed in this research. In this research, the effect of operating conditions of the oscillating bearing performing coupler-rocker motion on the heat generation is experimentally investigated and verified using mathematical model. For this purpose, a coupler-rocker bearing testing rig was designed and fabricated and the test bearing is splash-lubricated in an oil sump. The loading of test bearing was done using two extension springs. The applied load on the bearing was varied from 0 to 750 N while the crank rpm was varied from 1200 rpm to 1800 rpm. Three lubricant grades were used namely, SAE30, SAE40, and SAE50. Experimental results showed that the temperature of coupler-rocker bearing approaches steady-state at about 12 minutes for all cases. The steady-state temperatures at variable conditions are observed to follow a linear trend.

Performance evaluation of diamond nanolubricants applied to a refrigeration system

In this study, the experimental investigation of the use of nanolubricants based on polyol ester (POE) synthetic refrigeration oil and diamond nanoparticles at two mass concentrations, 0.1% and 0.5%, in a vapor compression refrigeration system is performed. An experimental apparatus has been developed in order to study the main parameters of a refrigeration system, such as cooling capacity, power consumption, the coefficient of performance, discharge and oil sump compressor temperatures, when diamond nanoparticles are used as a lubricant additive. The tests were performed under steady state conditions for R410A refrigerant in a scroll type compressor. The evaporation temperature and the input power frequency of the compressor were varied, while the condensation temperature was kept constant. The addition of diamond nanoparticles into the refrigeration system increased the cooling capacity and the coefficient of performance, while the discharge and the oil sump temperatures of the compressor were reduced.

Iterative Weight Reduction Process

In this article, iterative process for weight reduction was used by applying the design for manufacture and assembly process and FEM calculations. This study presents a successful development case of an oil sump structure of a large ship engine. Main structural modification was the transition from plate steel structures to sheet metal based panel structure. As a result of the iterative process, the weight of the developed oil sump was 40% lighter, and the natural frequencies were significantly increased. The study showed that the process allows designing the final product without massive prototyping. 1. Introduction There are several different core types for corrugated panels, for example, the X-profile, tube, Z-profile, hat-profile, and V-profile. The V-profile may need some special equipment for manufacturing and the profile is typically used for the lightest panels. Commercial availability of the hat-profile is better and the quality is often accurate enough for laser welding (Kujala & Klanac 2005). Laser welding is more challenging for V-profiles. In numerous applications, these metallic panels have shown very promising commercial possibilities due to excellent mechanical properties (Liang et al. 2001; Tian & Lu 2005; Zhang et al. 2015), but still there is a lack of public studies dealing with actual applications using good properties of the metallic sandwich panels for commercial solutions. Several research studies have been published in recent years on the analysis of metallic corrugated-core sandwich panels for strength, vibration control, noise control, and blast resistance. For example, Valdevit et al. (2006) noticed that buckling loads are hard to predict with Finite Element (FE)-simulations, but it is more suitable for limit loads. Zhang et al. (2015) investigated the dynamic responses of sandwich panels with triangular corrugated cores under air blast load. They noticed that sandwich plates suffered smaller back face deflections than equivalent solid plates at low impulses, but they were more sensitive to crack with bigger loads. Kujala and Klanac (2005) have also listed the main benefits of laser welded corrugated panels. These panels have shown, for example, good mechanical properties, such as thermal resistance, good vibration absorption, increased stiffness, and good blast loading resistance (Karlsson & Å ström 1997; Liang et al. 2001; Kujala & Klanac 2005; Tian & Lu 2005; Zhang et al. 2015). The fatigue strength of the laser-welded lap joints have been studied widely and the behavior is well-understood for different materials. For example, Cho et al. (2004) used finite element analysis to estimate fatigue strength for laser-welded lap joint successfully. Kamran et al. (2014) studied lap joints fatigue behavior of high strength low alloy steels. They noticed that the failure modes under quasi-static and cyclic loading are different. Under quasi-static loading condition, the crack will initiate from the base material and finally cracked through the lower sheet. Under low cycle loading, the crack will start growing from the preexisting crack tips and cracked through the lower sheet. When testing was made under high-cycle loading, the crack started to grow from preexisting crack tips and failed from the kinked fatigue crack through the upper sheet.

A Thermoelastohydrodynamic Analysis for the Static Performance of High-Speed—Heavy Load Tilting-Pad Journal Bearing Operating in the Turbulent Flow Regime and Comparisons to Test Data

Abstract Tilting-pad journal bearings (TPJBs) ensure rotordynamic stability that could otherwise produce dangerously large amplitude rotor oil-whirl/whip motions in high-speed rotating machinery. Currently, highly efficient turbo compressors demand an ever increasing rotor surface speed and specific load on its support bearings. The accurate prediction of bearing performance is vital to guarantee reliable products, specifically with regard to reducing maximum bearing pad temperature and drag power losses, and operating with the least flow rate while still maximizing load capacity. The hydrodynamic pressure and heat generation in an oil film acting on a bearing pad produce significant mechanical and thermal deformations that change the oil film geometry (clearance and preload) to largely affect the bearing performance, static, and dynamic. In addition, a high surface speed bearing often operates in the turbulent flow regime that produces a notable increase in power loss and a drop in maximum pad temperature. This paper details a thermoelastohydrodynamic (TEHD) analysis model applied to TPJBs, presents predictions for their steady-load performance, and discusses comparisons with experimental results to validate the model. The test bearing has four pads with a load between pads configuration; its length L = 76.2 mm and shaft diameter D = 101.6 mm (L/D = 0.75). The rotor top speed is 22.6 krpm, i.e., 120 m/s surface speed, and the maximum specific load is 2.94 MPa for an applied load of 23 kN. The test procedure records shaft speed and applied load, oil supply pressure/temperature and flow rate, and also measures the pads' temperature and shaft temperature, as well as the discharge oil (sump) temperature. The TEHD model couples a generalized Reynolds equation for the hydrodynamic pressure generation with a three-dimensional energy transport equation for the film temperature. The pad mechanical deformation due to pressure utilizes the finite elemental method, whereas an analytical model estimates thermally induced pad crowning deformations. For operation beyond the laminar flow regime, the analysis incorporates the eddy viscosity concept for fully developed turbulent flow operation. Current predictions demonstrate the influence of pressure and temperature fields on the pads mechanical and thermally induced deformation fields and also show static performance characteristics such as bearing power loss, flow rate, and pad temperatures. The comparisons of test results and analysis results reveal that turbulent flow effects significantly reduce the pads' maximum temperature while increasing the bearing power loss. Turbulent flow mixing increases the diffusion of thermal energy and makes more uniform the temperature profile across the film.

Experimental analysis on R290 solubility and R290/oil mixture viscosity in oil sump of the rotary compressor

The solubility of R290 in the oil and the R290/oil mixture viscosity in the oil sump of rotary compressors used in air conditioner are important parameters affecting the compressor reliability, system performance and R290 charged mass in system. In the study, a set of experiments were carried out in both compressor performance test platform and system psychrometric chambers for an R290 rotary compressor with mineral oil having high viscosity. The dynamic viscosity and temperature of R290/oil mixture at some points within the oil sump of compressor, besides the temperature on shell outside corresponding oil sump and the performance parameters of compressor or air conditioner were measured under different cooling and heating conditions. The variation ranges of oil sump mixture viscosity and R290 solubility were given. The saturated solution temperature and superheat degree of oil sump mixture were proposed and calculated. The effect of compressor suction superheat on the oil sump superheat and its effect on solubility and viscosity was analyzed. A greater suction superheat degree was suggested for an R290 air conditioner with mineral oil in terms of compressor reliability because of the low discharge temperature of R290 compressor.

Oil Degradation in a Diesel Engine with Dual-Loop Lubricating System

ABSTRACT A common lubricating oil sump is used in most modern internal combustion engines for cooling, wear protection, and friction reduction. This requires compromises during base oil and additive selection as a result of differing needs for lubricant performance in engine subsystems. The use of a dual lubricating loop, providing separate oil sumps for the power cylinder and valve train subsystems, was investigated experimentally to determine the effect of system segregation on oil degradation. A small diesel engine was modified, installed in a commercial generator unit, and operated for one oil drain cycle. Oil sampling was tailored to assess base and acid numbers, oxidation, soot concentration, water content, and viscosity changes. The experiment complemented an earlier study that investigated the fuel economy benefits of such a lubricating configuration. These include longer drain intervals for the cylinder head and power cylinder subsystems, improved wear performance for the valve train, and opportunities for alternative material selection during engine design. The experiment demonstrated protection of the valve train subsystem from soot contaminants in the power cylinder. Lower total acid number and oxidation tendency was also observed in the valve train.

IMPROVING THE EFFICIENCY PREPARATION OF OIL JOINT SELECTION OF SOLIDS AND ASPHALTENES OF INTERMEDIATE LAYERS

In the present work, the possibility of joint separation of mechanical impurities and asphaltenes from intermediate layers of oil sump with the use of limiting hydrocarbon solvents and the centrifugation method was investigated, and an assessment of the effect of the separation stage on the efficiency of the oil dehydration processes was carried out. It is shown that the dilution of the hydrocarbon phase of the intermediate layers with a solvent from the saturated hydrocarbons (a broad fraction of light hydrocarbons from the oil stabilization block is used as the solvent), followed by centrifugation, allows the separation of heavy hydrocarbons, mainly asphaltenes and mechanical impurities into a separate phase. The analysis of structural and group structure of an initial hydrocarbonic phase and the allocated deposit showed that in settling 81.6 % of a mass fraction of asphaltenes and 93.6 % of a mass fraction of mechanical impurities of their initial con-tents in a hydrocarbonic phase of the interlayer concentrate. The ultimate analysis of structure of the deposit determined by a method of a X-ray fluorescent spectroscopy showed the high content of vanadium (0.4 % of a mass fraction) comparable to the main-tenance of this element in metallic ores that allows to use the allocated deposit for pro-cesses of a demetallization. Comparative tests of sediment influence on oil dewatering processes performed with the use of a bottle dough in the presence of an industrial demulsifier at the technological parameters of the dewatering unit of the oil treatment unit showed that the separation of the sediment from the hydrocarbon phase of the intermedi-ate layer substantially increases the efficiency of the oil dehydration processes. Results of the executed research can be used for creation of technology of utilization of interlayers of settlers of the oil directed to increase in effectiveness of processes of a deaquation and decrease in number of technological failures of installations of preparation of oil.

Impact of oil aging and composition on the morphology and structure of diesel soot

HypothesisSoot is a black powder-like substance consisting of carbonaceous amorphous particles, formed by incomplete combustion of hydrocarbons. In the last decades, industrial research on lubricant oils has grown to develop more efficient formulations, mainly to reduce the formation of soot in oil so to increase engine lifetime. The comprehension of the mechanism of soot formation and particles growth/aggregation in times during real applications is of fundamental importance for the design of better performing lubricants. ExperimentsIn this work, we report on a multi-technique investigation of soot-in-oil samples, drawn from the oil sump of a direct-injected heavy-duty diesel engine at increasing working times in a standard engine test. Scanning Electron Microscopy, Small Angle X-ray Scattering and Dynamic Light Scattering are employed to study the evolution in term of soot size, morphology and fractal dimensions. FindingsOur results evidence that, in a complete lubricant formulation, exhaust oil viscosity evolution correlates well with the increase of soot amount inside the oil. Moreover, the growth of both primary soot particles and aggregates during the engine test is limited to about 24 and 200 nm, respectively, because of the active role of the dispersant present in the investigated oil.

NOISE CONTROL OF VEHICLE DRIVE SYSTEMS

The paper presents an overall simulation approach to control the noise emission of car engines at a very early stage of the design process where no real prototypes are available. The suggested approach combines different physical models and couples different software tools such as multi-body analysis, fluid dynamics, structural mechanics, magneto-electrodynamics, thermodynamics, acoustics and control as well. The general overall simulation methodology is presented first. Then, this methodology is applied to a combustion engine in order to improve its acoustical behavior by passive means, such as changing the stiffness and the use of damping materials to build acoustic and thermal encapsulations. The active control by applying piezoelectric patch actuators at the oil sump as the noisiest part of the engine is discussed as well. The sound emission is evaluated by hearing tests and a mathematical prediction model of the human perception. Finally, it is shown that the presented approach can be extended to electric engines, which is demonstrated at a newly developed electric wheel hub motor.

Modification of a compressor performance test bench for liquid slugging observation in refrigeration compressors

Compressor performance test procedures are defined by the standard DIN EN 13771, wherein a variety of possible calorimeter and flow rate measurement methods are suggested. One option is the selection of two independent measurement methods. The accuracies of both selected measurement methods are essential. The second option requires only one method. However the measurement accuracy of the used device has to be verified and recalibrated on a regular basis.The compressor performance test facility at the Technische Universitaet Dresden uses a calibrated flow measurement sensor, a hot gas bypass and a mixed flow heat exchanger. The test bench can easily be modified for tests of various compressor types at different operating ranges and with various refrigerants. In addition, the modified test setup enables the investigation of long term liquid slug and its effects on the compressor. The modification comprises observational components, adjustments of the control system, safety measures and a customized oil recirculation system for compressors which do not contain an integrated oil sump or oil level regulation system. This paper describes the setup of the test bench, its functional principle, the key modifications, first test results and an evaluation of the energy balance.

Determination of the oil distribution in a hermetic compressor using numerical simulation

In addition to the reduction of friction the oil in a hermetic compressor is very important for the transfer of heat from hot parts to the compressor shell. The simulation of the oil distribution in a hermetic reciprocating compressor for refrigeration application is shown in the present work. Using the commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent, the oil flow inside the compressor shell from the oil pump outlet to the oil sump is calculated. A comprehensive overview of the used models and the boundary conditions is given. After reaching steady-state conditions the oil covered surfaces are analysed concerning heat transfer coefficients. The gained heat transfer coefficients are used as input parameters for a thermal model of a hermetic compressor. An increase in accuracy of the thermal model with the simulated heat transfer coefficients compared to values from literature is shown by model validation with experimental data.

Experimental investigation of dynamic characteristics of a rotary compressor and its air conditioner using R290 during warm startup

The object of this research was to experimentally study the dynamic characteristics of an R290 rotary compressor and its air conditioner during warm startup under a cooling condition. These dynamic characteristics included pressure changes in the cylinder and system, temperature changes in the compressor shell and system, the viscosity of refrigerant/oil mixture in the oil sump and liquid level of the oil sump. All experiments were carried out in the psychrometric rooms, in which the humidity and temperature kept constant. Experimental results showed that the minimum suction pressure (390kPa) during the warn startup was greater than that of the cold startup (145kPa). During the initial stage of warm startup process, a small amount of liquid was founded in the cylinder as the pressure increased rapidly to 1.7MPa in 1s. The viscosity and liquid level ranges in the compressor for the warm startup were smaller than that of the cold startup under the same cooling condition. This indicated that warm startup kept the R290 compressor a better-lubricated state and less oil was pumped into the system during the startup process.

Experimental Investigations to Use Splash Lubrication for High-Speed Gears

In order to use electric motors which run up to 40,000 rpm in future automotive applications, this study aims to experimentally investigate if splash lubrication technique is worth considering for high-speed gears, i.e., for tangential gear speed up to 60 m/s. To this end, a specific test rig has been used to operate a single spur or helical gear in various operating conditions (lubricant, oil sump volume, temperature, etc.). Churning loss is measured and, as the fraction of air in the lubricant (namely, oil aeration) can be influential on this source of dissipation, a specific sensor is also employed for online monitoring of oil sump aeration. By inserting some moveable walls in the gearbox, it is demonstrated that churning losses and oil aeration can be significantly reduced by mounting these flanges at an appropriate distance to the gear lateral faces. Based on dimensional analysis, an engineering criterion is proposed to properly choose the clearance between the tested gear and the flanges.

Nodal modelling for advanced thermal-management of internal combustion engine

The evolution of temperatures in internal combustion engines during cold start is quite important. This greatly affects fuel consumption and vehicle emissions. In this paper, an advanced thermal management model is presented and used on an automotive Diesel engine in order to determine the evolution of the different temperatures during warm-up stage. The paper focuses on the complete description of the engine components, coolant circuit, and lubricant circuit. The objective is to calculate the heat exchanges between the thermal masses of sub-models (cylinder head, engine block, pistons, oil sump…) and the fluids. Experiments on an engine were realized in order to calibrate the model (heat release, friction losses…) but also to obtain the temperature evolutions during transient stage. These last results were used in order to validate the model. This approach gives the possibility to determine the coolant and oil temperature evolution with a minimum of nodes and a relatively short calculation time. The evolution of the coolant temperature in a vehicle during a NEDC cycle with a cold start was studied. A good agreement was obtained. Finally, the model was used in order to study the possibilities to reduce the vehicle mass by a reduction of the engine mass.

The impact of microgeometry pistons with a stepped bearing surface for the friction loss of the internal combustion engine

This paper present the results of experimental piston friction losses on stepped bearing surface microgeometry obtained on the test rig. This test rig is equipped with special temperature control system, which provides better stability to temperature than in standard systems. The results of station tests was discussed. Tests was analyzed depending the moment caused by the friction on the oil temperature in the oil sump. Specified conclusions allow to assess the impact of the stepped profile of the pistons bearing surface microgeometry for different values of engine speed and the oil temperature at the friction losses in the main kinematic engine node which is piston-cylinder.