Preparation of Nickel-Based Nanolubricants and Investigation of their Tribological Behavior

In situ surface-modification technique is adopted in present research to fabricate a series of Ni nanoparticles as well as Cu@Ni nanoparticles with different size and morphology. The correlation among the composition, structure, size, and morphology and tribological properties of as-synthesized additives were explored, and the friction-reducing, antiwear, and worn surface self-healing mechanisms of the additives were discussed. It was found that Ni nanoparticles with a smaller size show higher surface activity and can readily deposit on the sliding surface and form a stable and continuous protective layer thereon. Compared with sphere-like and triangular rod-like Ni nanoparticles, triangular plate-like Ni nanoparticles are more liable to form protective layer. Compared to Ni-based nanolubricants, as-synthesized Cu@Ni nanolubricants exhibit better friction-reducing, antiwear, and extreme pressure properties. It is because the highly active Ni nanocores and O- and N-containing organic modifying agents can readily form boundary lubricating film on sliding steel surfaces, while Cu nanocores can easily deposit on sliding steel surface to form a protective layer (self-healing film) thereon. Ni nanoparticles as nanoadditives in solid-liquid lubricating system significantly reduce the friction in all lubrication regimes: As a nanolubricant, Ni nanoparticles exhibit popular and effective friction-reducing, antiwear, and extreme pressure properties

Dynamic Performance of Valve in Reciprocating Compressor Used Stepless Capacity Regulation System

Capacity regulation system by controlling suction valve is useful for large scale reciprocating compressor in petrochemical engineering field. The dynamic performance of adjustment device influences the stability and accurancy of this system. In this paper, a mathematical model of adjustment device coupled with the motion of suction valve is built, and the dynamic performances of valve plate are simulated. The results show that the displacement of actuator increases with the hydraulic oil pressure until the valve plate is keeped to be opened. The closing process of valve plate is delayed when the hold time of actuator is larger enough. Although the gas flow rate and power consumption of comressor decrease with the relax angle of actuator, the power is also consumed when the gas is not discharged through the discharge valve. The closing time decreases with the reset spring stiffness but increases with the diameter of hydraulic

Experimental Research on Surge and Stability Enhancement of Centrifugal Compressor

Centrifugal compressors are wildly used in many process industries. The stability of centrifugal compressor is one of the most important performances. When the compressor operates at the small volume flow rate, the working conditions of rotating stall and surge will occur, which lead to the unstable condition for centrifugal compressor. The signals of compressor are tested and analyzed when surge condition occurs in this paper. In addition, a new method to improve the compressor stability is proposed. It is called the active control casing treatment (ACCT) system. The flow in the compressor impeller is changed by the ACCT system and the stability of compressor is improved. The experimental researches have been done in this paper. The test results of ACCT system are also discussed in this paper

Performance Analysis of Centrifugal Compressor under Multiple Working Conditions Based on Time-weighted Average

A method of compressor performance analysis under multiple working conditions is present based on the Time-weighted average (TWA). The main operation parameters can be obtained based the estimate of the working conditions and times of compressors. Then the comprehensive analysis method can be used to get the overall performance of compressor. The performance of a basic centrifugal compressor was simulation by CFD method in this paper. The overall performance of the centrifugal compressor is calculated under different working conditions. The TWA analysis method can be used as a tool to evaluate the overall performance of compressor. And it can also be used during the design phase to improve the performance of compressor fundamentally

Modelling methane emissions and grain yields for a double-rice system in Southern China with DAYCENT and DNDC models

Acknowledgements This work contributed to the following projects: EU Horizon 2020 programme (SuperG) and The Scientific and Technological Innovation Special Fund Project of Carbon Peak and Carbon Neutrality in Jiangsu Province (No. BE2022311). The first author (Yang Guo) gratefully acknowledges financial support from China Scholarship Council (CSC).Peer reviewedPublisher PD