Compressor Oil Research Articles

Blocking of Gas–Liquid Coalescing Filters with Accumulated Oil during the On–Off Operation of a Filtration System

The study aims to eliminate the effect of coalescing filter blocking due to on–off operation by changing the wetting properties of the non-woven fiberglass filter media through their chemical modification with the use of a polydimethylsiloxane (PDMS) solution in hexane and a few commercial products that give the surface oleophobic properties. The best results—high separation efficiency, no redispersion of droplets at the outlet, and low flow resistance—were obtained for materials coated by immersion in a 0.2% PDMS solution, for which a reduction in oleophilicity was found, but the material was not oleophobic and still moderately wetted with the test liquid. The corresponding static contact angle with the VG-46 rotary compressor oil measured on the flat borosilicate glass wafer made of the same material as the fiberglass media was equal to 54° for the PDMS dip-coated surface. Moreover, the good stability of the applied polymer on the material surface was confirmed by the SEM imaging, the FTIR analysis, and maintaining a high performance in multiple tests run for a single coalescing element.

Status Monitoring System of Reciprocating Hydrogen Compressor Based on Hilbert−Huang Transform

ABSTRACTA reciprocating hydrogen compressor status monitoring system for predictive maintenance is developed based on HHT (Hilbert−Huang Transform) with multiple functions, strong applicability, and high accuracy to address the problem of difficulty in identifying fault signals and failure to provide advance warning before faults occur in the reciprocating hydrogen compressor state monitoring system. Design framework of monitoring system is confirmed, and function modules are designed based on LabView platform. HHT is applied to monitor the status of reciprocating hydrogen compressor based on LabView platform. A reciprocating hydrogen compressor is selected as research object, status monitoring analysis is carried out. Five working states of reciprocating hydrogen compressor are collected, which conclude normal state, filler malfunction, cross‐head malfunction, air valve malfunction, and piston rod malfunction. HHT is carried out for five signals, and results show that HHT marginal spectrum of five signals has different characteristics. Based on comparison results, precision of HHT ranges from 0.757 to 0.784, recall of HHT ranges from 0.738 to 0.766, F1‐score of HHT ranges from to 0.788 to 0.804, HHT has better performance than other two methods. Proposed monitoring system designed in this study provides a comprehensive and efficient online monitoring and data analysis solution for reciprocating hydrogen compressors, which can achieve fault prediction of reciprocating hydrogen compressor, reduce failure rate, and effectively improve the reliability of the compressor oil injection system.

Thermal Performance of Vapour Compression Refrigeration System using Bimetallic Strontium Hexaluminate Nanorefrigerants

Nanoparticles are added to standard compressor lubricants to improve performance and reduce the energy consumption of vapour compression refrigeration systems (VCRS). This work evaluated the compatibility, viability, and utility of a bimetallic oxide strontium hexaluminate (SrAl12O19) nano-lubricant with nominal sizes of 20–40 nm by characterising and evaluating its thermophysical properties while assessing its effect on the performance and energy consumption of existing, unmodified VCRS. Eco-friendly R600a were used as the system's refrigerant and the performance, energy consumption, and energy efficiency of VCRS were investigated by altering the concentration of SrAl12O19 (1%–20%) in the compressor lubricant. The results showed that as the temperature increases, the viscosities significantly decreased and increased as the concentration of nanoparticles is increased. In contrast, the density and acidity of the nanolubricant increased as the volume concentration of nanoparticles increased. The addition of nanoparticles into the compressor oil enhanced the performance of the VCRS performance and reduced the energy required to operate the system; however, these performance metrics decreased as the concentration of nanoparticles increased further. When the concentration of nanoparticles increased, exergy efficiency reached the maximum at 5% volume concentration.

CFD Analysis of Improving Air Conditioning System Performance By Adding SiO2 Nanoparticles To The Compressor Oil

The overall performance of air-conditioning systems is necessary to evaluate the comfort conditions and equipment life. in order not to varnish energy. The aim of this study is to improve performance of air conditioning by adding nanoparticles to oil of compressor. The research applied computational fluid dynamics CFD to simulate the use of SiO2 nanoparticles in air-conditioning systems. Silicon dioxide (SiO2) nanoparticles have better thermal properties than pure oil and can also significantly enhance the performance of compressor oils as well as heat transfer capability in HVAC systems. This research investigates the reactions between (0.1%, 0.4%, and %0.7) of SiO2 nanoparticles with compressor oil, to determine their impacts on heat dissipation, lubricant efficiency as well as performance overall. Results show that the addition of nanoparticles to the oil lubricant increases the COP of the air conditioning system.

EXPERIMENTAL INVESTIGATION OF EFFECTS OF NANOREFRIGERANTS ON VAPOR COMPRESSION REFRIGERATION SYSTEM USING R1234yf INSTEAD OF R134a

In this study, the usage of refrigerant R1234yf was experimentally investigated with the addition of various nanoparticles instead of R134a as a working fluid in a VCRS. Firstly, the usage of pure R1234yf instead of R134a was experimentally investigated with energy and exergy approaches without any modification in the VCRS. As a result of pure refrigerant experiments, it was determined that the compressor power input increased by around 9%, cooling capacity decreased by around 8% and EER decreased by around 17% in the system using R1234yf compared to the system using R134a. Additionally, it was determined that the second law efficiency of the VCRS reduced by around 8% in the system using R1234yf compared to the system using R134a. Then, Al2O3, graphene or CNT nanoparticles were added for compensate for performance drops to the VCRS using R1234yf via compressor oil at various mass fractions. Thus, the best enhancement in the system performance parameters was obtained with the usage of R1234yf including 0.250% graphene by mass. Accordingly, it was observed that the cooling capacity of the system with R1234yf including 0.250% graphene by mass was improved up to 24% and 14% compared to the VCRS with pure R1234yf and R134a, respectively. Consequently, the EER value of the VCRS with R1234yf including 0.250% graphene by mass was enhanced up to 32% and 13% compared to the system using pure R1234yf and R134a, respectively. Additionally, the second law efficiency of the system slightly increased with the usage of R1234yf including 0.250% graphene by mass.

Visualization of vane chattering in rotary compressor

In this study, the impacts of various factors on the chattering phenomenon in sliding vane compressors, which is a crucial aspect that influences their performance and efficiency were explored. The analysis focused on the compressor rotational speed, pressure ratio, and operating temperature, considering both ambient and heated conditions. The aim was to provide a comprehensive understanding of the relationship between these factors and the occurrence of chattering at different operational intervals, as well as the vane sealing performance and adherence to the chamber wall.The methodology involved examining vane behavior and the chattering occurrence across three intervals under various conditions, specifically looking at oil films formation and sealing performance degradation. The experimental results provided notable insights into the chattering phenomenon. It was shown that as the pressure ratio increased and the compressor rotational speed decreased, the sealing performance deteriorated. Moreover, when operating under heated conditions, a decrease in oil viscosity leads to reduced friction between the vane and bearing, improving vane adherence compared to ambient conditions.The methodology and findings of this study provide insights into the chattering phenomenon in vane compressors by considering the interplay between various factors. The results emphasize the importance of optimizing the compressor oil refueling flow, rotational speed, pressure ratio, and operating temperature, to ensure proper lubrication and efficient interaction between the vanes and compression chamber walls for improved compressor performance and reduced operational challenges.

Spallation Neutron Source reliability improvement projects for the Cryogenic Moderator System

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) operates the Cryogenic Moderator System (CMS) which provides supercritical hydrogen cooling at 20K to three neutron moderators. A helium refrigerator provides 8 kW of cooling capacity to three parallel hydrogen circuits. Several projects have been completed to improve the operational reliability of the CMS. The status of helium compressor oil removal system, helium oil processor, helium purity monitoring, hydrogen circulator bearing investigation and operational procedure improvement will be presented. Future plans for sustained reliable operation at design capacity will also be presented.

Heating and defrosting performance assessment of dual-source heat pump operational modes under various ambient conditions

Multifunctional dual-source heat pump systems, featuring two sets of heat exchangers (air-to-refrigerant and water-to-refrigerant) in series or parallel, aim to boost efficiency. However, these systems often require extensive piping, leading to power losses, higher energy consumption, and increased installation space requirements. Furthermore, few comparative studies have assessed the effectiveness of dual-source versus single-source heat pump systems under various ambient conditions. This study introduces a novel air-water dual-source evaporator design that enables efficient heat exchange using air, water, or both. With this design, the heat pump system can be tuned according to three distinct modes: pure water-source mode (WSHP), pure air-source mode (ASHP), and dual air-water-source mode (AWSHP). The heat pump's efficiency across these modes was evaluated under various weather conditions, adhering to the CNS15466 and GB/T21362 standards. The findings reveal a strong correlation between the operational modes and ambient temperatures, indicating that maximum efficiency is achieved with the WSHP mode below 7 °C, AWSHP mode between 10 °C and 35 °C, and ASHP mode above 35 °C. Moreover, three defrosting methods were evaluated: hot gas bypass, hot water bypass, and a combination of both. The hot water bypass, in conjunction with the proposed dual-source evaporator design, efficiently performed full defrosting, boosting system efficiency. The ability of the heat pump to switch between operating modes enhances the overall energy efficiency during space heating and defrosting, reduces installation space requirements and compressor oil loss, and facilitates hot water production. The proposed system is ideal for various industrial applications requiring efficient operation under diverse ambient conditions.

A novel order-separated generalized feedforward design for motion control in energy-efficient electrohydraulic system with proportional and integral feedback

Existing feedforward, or FF, controllers are based on differentially flat models. For double-acting single-rod cylinders, more compact than the double-rod ones, flat models could be constructed either under an incompressible-flow assumption for low-pressure, slow-response applications or for a matched valve-cylinder combination. Contrasting the existing models tackling only a single nonlinear aspect like valve leakage, oil compressibility or friction, a novel FF controller, generalized for different types of valve-cylinder-pump combinations, has been developed here. It is based on the highest-order assumption of incompressible flow that sustains the piston motion. An FFPI controller has been implemented in a laboratory setup for displacement tracking against sinusoidal demands up to 9 Hz frequency. The FF parameters has been estimated by minimizing the deviation of simulation prediction from an offline experimental time-varying response. The PI gains have been selected through a stability analysis by extending Routh criteria for linearized time-variant error dynamics. Comparison against a PI-only controller with identical gains has established the energy-saving potential of the FFPI controller both working with the same variable-displacement pump. In comparison to existing nonlinear adaptive controllers, more precise and smoother responses have been obtained over wider frequency range at lower control expenses, admittedly with occasional marginal penalty in the phase variation. The FFPI controller has exhibited the shortest transient and the highest resilience against measurement noise.

Impacts of Using AlO Nano Particle to Compressor Oil on Performance of Automobile Air Conditioning System

Impacts of Using AlO Nano Particle to Compressor Oil on Performance of Automobile Air Conditioning System

Influence on the Energy Conservation and Green Environment R152A Refrigeration with Various Nanorefrigerants

Global Warming Potential (GWP) has proven to be just as critical in determining a possible coolant in recent years as Ozone Depletion Potential (ODP). By lowering the refrigerant charge and enhancing the coolant containment systems, R152A emissions are now aggressively reduced. The option to use the R152A device must be discussed due to concerns about its global warming potential. Disperse the specified quantities of nanoparticles in the compressor oil using a magnetic stirrer for two hours, and then ultrasonic dissolve for four hours to prepare the necessary volume fractions. The experiments showed a performance improvement using CuOs with 0.5% volume fractions with a base refrigerant such as R152A. Experimental results from three different nanoparticles, such as CuO, ZnO and Al2O3, indicate strong miscibility of the nano-CuO lubricant and an increase in lubricity oil to two nanoparticles.

Experimental and numerical analysis of two different bottom pumps of a hermetic reciprocating compressor at low speeds

Operating at low speeds (< 2000 rpm) is critical in achieving optimal energy efficiency for inverter-type hermetic reciprocating compressors. However, ensuring the efficient delivery of lubrication oil to the compressor components at such low speeds is challenging.The hermetic reciprocating compressor crankshaft utilizes a machined helical channel on the outer surface to provide lubrication oil to the upper bearings. The lubrication oil is provided to this channel's inlet from the compressor's oil sump by an eccentric internal channel in the bottom of the crankshaft. However, this design cannot deliver the oil to the helical channel under low-speed conditions. This research investigates a screw pump, the smooth inner crankshaft wall with threaded pin inside (SC-TP) configuration, and compares its performance numerically and experimentally with a conventional double eccentric internal channel pump (DEC) design.For this purpose, computational fluid dynamics (CFD) is used. For the simulation validation, the pumps are fabricated from transparent plexiglass. Also, two sets of solvers for two-phase flow, i.e., the implicit volume of fluid model (VOF) with Compressive scheme and explicit VOF model with Geo-Reconstruct scheme, are used to examine the methods’ accuracy. When running above 1400 rpm, the DEC pump delivers faster and more oil than the screw pump. However, while operating under 1400, the screw pump provides oil until 800 rpm, which the DEC pump cannot do. This research shows how shear force dominates centrifugal force during low-speed pumping situations and also investigates how different viscosities impact performance.

Experimental investigation on startup process of R290 air-source heat pump with different lubricants

The low density, small adiabatic index, and restricted charge of R290 result in different startup characteristics for R290 air-source heat pumps (ASHP) from that for HFCs ASHP. The research on the startup process of R290 refrigeration systems in the past has focused on system and compressor pressures, temperatures, changes in the bottom viscosity of the oil sump, and control strategies. There is a lack of research on the effect of lubricant types on the startup process, especially for R290 air-source heat pump. This paper experimentally measured and analyzed the changes in system temperatures and pressures as well as the changes in refrigerant concentration, concentration gradient, and mixture viscosity in the compressor oil sump during the startup process of R290 ASHP under different conditions, different startup types and with different lubricants. In addition, the oil discharge time, oil discharge, refrigerant mass in the compressor, and oil return time during the cold startup of LTH using PAG VG40 and MO VG100 were observed and clarified by installing transparent tubes and dismantling and weighing method. The experimental results showed that during the startup process, the mixture viscosity in the oil sump decreased and then increased, the refrigerant concentration increased and then reduced, and the refrigerant concentration gradient went from present to absent. The minimum viscosity was greater, the maximum concentration was smaller, and the low-viscosity duration was shorter for higher initial compressor temperature and with poorer miscible lubricants. PAG VG40 and MO VG100 showed good oil return performance.

An improved coupled flow-geomechanical model for cyclic steam stimulation

Considering the pore deformation and permeability changes during dilation-recompaction in cyclic steam stimulation (CSS), an existing geomechanical model is improved and thermo-mechanically coupled with the flow equations to form a coupled flow-geomechanical model. The impacts of dilation-recompaction parameters can be quantified through sensitivity analysis and uncertainty assessment utilizing the synergy between Latin hypercube designs and response surface methodology. The improved coupled flow-geomechanical model allows a more reasonable history-matching of steam injection pressure and volume and oil/water production volume. In both the linear and quadratic models, the rise in recompaction pressure has the most significant effect on the rise in the volumes of steam injection and water production, both rock compressibility and recompaction pressure are positively correlated with steam injectivity and oil/water production, and the dilation pressure is negatively correlated with steam injectivity and oil/water production. In the linear model, dilation pressure has the most significant negative impact on the cumulative oil production, and compressibility and recompaction pressure are positively correlated with oil production. In the quadratic model, the rise in recompaction pressure has the most significant effect on the rise in the cumulative volumes of oil/water production and steam injection. The interactions between the dilation/recompaction pressures and spongy-rock compressibility negatively affect the cumulative volumes of oil/water production and steam injection.

Influence of lubricating oil circulation characteristics on the performance of electric vehicle heat pump system under low temperature conditions

Electric vehicles frequently employ heat pump systems for winter heating. In winter low-temperature environments, the viscosity of lubricating oil increases, forming an oil film as the refrigerant enters the heat exchanger, consequently impacting the heat transfer efficiency and overall performance of the heat pump system. This paper presents the design and implementation of an experimental heat pump system tailored for electric vehicles. The experimental setup incorporates a specialized device for lubricating oil sampling and an assessment methodology for evaluating heat pump functionality. Under a range of low-temperature conditions, the system underwent comprehensive testing, enabling a detailed analysis and synthesis of the flow characteristics and the influence of lubricating oil within both the heat pump system and the heat exchanger. The results reveal that the oil circulation rate is directly affected by the compressor oil charge, and maintaining the oil circulation rate within the range of 3 %–4 % results in a peak COP of the system. When the ambient temperature is 0 ℃ and the oil filling volume is 200 g, the oil circulation rate is 3.87 %, and the COP can reach 1.93. In addition, as the oil retention in the evaporator increases by 15.67 g, the COP value decreases by 21 %. Similarly, the increase in oil retention in the condenser from 2.43 g to 6.25 g resulted in a corresponding decrease in heat transfer capacity of 0.07 kW/K, leading to an overall deterioration of the system's performance.

An Improved Model for Hysteretic Behavior Investigation on the Twin-tube Hydraulic Adjustable Damper

The damper, as an integral constituent of the automotive suspension system, assumes a critical function in determining the suspension’s overall performance. To enhance the ride comfort and stability of automobiles, further research on the performance of dampers is particularly important. In this paper, an improved mathematical model with a twin-tube hydraulic adjustable damper (THAD) was developed to analyze the hysteretic behavior. The cavitation process of THAD was studied by studying the compressibility of oil and the structure of the valve port. Mathematical model results and published data under compression stroke and rebound stroke are compared for different working situations. The simulation results consistently illustrate the correctness of the model.

Squeeze Film Effect and Its Influence on the Lubrication Characteristics of Slipper Oil Film under Pressure Pulse

This study aims at the lubricant film between the slipper and swashplate of an axial piston pump. Based on a single piston/slipper assembly model, a mathematical model for the squeeze film effect is developed according to the pressure-flow transfer process as well as the dynamics of the piston/slipper assembly. The squeeze film effect on the slipper lubricant film has been predicted by nonlinear numerical calculations and computational fluid dynamic (CFD). The slipper lubricant film thickness and leakage flow, sealing land pressure distribution, and load carrying capacity are evaluated as important parameters to indicate the performance of slipper oil film. The influence of piston/slipper assembly geometric parameters, oil compressibility, and oil viscosity on the squeeze film effect under pressure pulse has been studied, and the effect of squeeze film speed on the support force of slipper lubricant film has been given out.

New Correlation for Predicting Undersaturated Oil Compressibility for Mishrif Reservoir in the Southern Iraqi Oil Fields

Reservoir fluids properties are very important in reservoir engineering computations such as material balance calculations, well testing analyses, reserve estimates, and numerical reservoir simulations. Isothermal oil compressibility is required in fluid flow problems, extension of fluid properties from values at the bubble point pressure to higher pressures of interest and in material balance calculations (Ramey, Spivey, and McCain). Isothermal oil compressibility is a measure of the fractional change in volume as pressure is changed at constant temperature (McCain). The most accurate method for determining the Isothermal oil compressibility is a laboratory PVT analysis; however, the evaluation of exploratory wells often require an estimate of the fluid behavior prior to obtaining a representative reservoir sample. Also, experimental data is often unavailable.Empirical correlations are often used for these purposes.This paper developed a new mathematical model for calculating undersaturated oil compressibility using 129 experimentally obtained data points from the PVT analyses of 52 bottom hole fluid samples from Mishrif reservoirs in the southern Iraqi oil fields. The new undersaturated oil compressibility correlation developed using Statistical Analysis System (SAS) by applying nonlinear multiple regression method. It was found that the new correlation estimates undersaturated oil compressibility of Mishrif reservoir crudes in the southern Iraqi oil fields much better than the published ones. The average absolute relative error for the developed correlation is 7.16%.

Filtracja ściśliwego oleju lepkoplastycznego w medium porowatym

Numerous laboratory studies have shown that the change in physical and chemical properties and the geological conditions of the occurrence of hydrocarbons depend on depth. It should be noted that the change in oil properties with depth and the identification of the properties of such oils are poorly understood. In this research work, an attempt is made to study the filtration properties of anomalous oils, taking into account compressibility in reservoir conditions. The work carried out shows that the density, dynamic viscosity and the content of resins, sulfur, paraffin and asphaltene of different oil reservoirs are mainly depth dependent. The filtration characteristics of such oils that manifest themselves at a given pressure have been established. The results of modeling the filtration processes leading to the emergence of zones of increased oil compressibility, forming deep hydrocarbon fields, were used to discuss the regularities obtained. This makes it possible to determine filtration characteristics of anomalous liquid, taking into account the compressibility, which determine their higher quality indicators. The analysis shows that in the development of oil fields with anomalous properties of hydrocarbons, when recalculating the volumetric flow rate of individual wells in reservoir conditions it is necessary to use the value of the volumetric oil coefficient, taking into account its non-Newtonian properties. This technique will enable future works to study the effect of hydrodynamic imperfection of wells and the effect of formation permeability violation in their bottomhole zone on the reservoir pressure redistribution characteristics and well test results.

Anti-Vibration Control of Turntable Ladders by a Steel Rope-Hydraulic Control System

Anti-vibration control of turntable ladders is effective by controlling the steel ropes inserted in the hollow handrails. Previous studies that considered idealized conditions, such as ignoring friction, piston mass, and hydraulic oil compressibility, can not be strongly generalized. This study addresses these problems by describing in detail the equipment serving the anti-vibration solution, building a mathematical model for the steel rope hydraulic control system considering the above factors, and controlling the rapid extinguishing of vibrations on a model simulated in Matlab-Simulink. Furthermore, the simulation of the relationship between the control signal and oil flow through the proportional distribution valve produced a signal flow curve that was asymptotic to the actual. The results showed a difference compared to previous studies. Although the solution was only implemented on the lowest ladder section with the most unfavorable conditions, the time for vibration on the top ladder reached amplitudes of 3 and 5mm in 3 and 5s for empty and full baskets, respectively.