scholarly journals Mustafa Ozsipahi, Sertac Cadirci, Hasan Gunes, Husnu Kerpicci, Kemal Sarioglu

2020 ◽  
Vol 7 ◽  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Internal Surface ◽  
Suction Side ◽  
Oil Viscosity ◽  
Two Phase ◽  
Oil Film ◽  
Lubricant Oil ◽  
Immiscible Mixture

The aim of this study is to numerically investigate theeffects of various parameters on the lubricant (oil)-coolant two phaseflow in the lubrication system of hermetic compressors commonlyused on household refrigerators. Lubrication oil is pumped from thesump through an asymmetrically opened hole on the bottom of thecrankshaft (suction side or inlet) by its rotational motion and climbsas an oil film on the internal surface of the helical channel carved onthe crankshaft surface. This oil film is directed to crankshaft upperexit discharging into the coolant refrigerant and it is used tolubricate the moving components of the compressor including thecylinder piston. The oil forms an immiscible mixture with coolant,thus a two phase flow model using Volume of Fluid (VOF) method isused. Specifically, the mass flow-rate of oil is determined as afunction of the rotational speed, oil viscosity and the submersiondepth of the crankshaft in the oil-sump. With increasing rotationalspeed and submersion depth, the mass flow-rate through thecrankshaft upper exit also increases. With increasing oil viscosity themass flow-rate through the crankshaft upper exit decreases due to theincreased friction.

Numerical Simulation of Lubrication System in a Hermetic Reciprocating Compressor

2014 ◽  
Author(s):  
Mustafa Ozsipahi ◽  
Sertac Cadirci ◽  
Hasan Gunes ◽  
Kemal Sarioglu ◽  
Husnu Kerpicci
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Numerical Study ◽  
Lubrication System ◽  
Reciprocating Compressor ◽  
Oil Viscosity ◽  
Two Phase ◽  
Oil Film

The aim of this numerical study is to investigate the lubrication system of a household hermetic reciprocating compressor. The effects of the rotational speed, oil viscosity and crankshaft-to-oil sump bottom distance on the oil-air two phase flows are investigated in detail. Necessary oil to lubricate the components of the compressor is sucked from the oil sump through an asymmetrically opened suction hole of the crankshaft by its rotational movement and climbs as an oil film on the helical channel carved on the shaft wall. This oil film is directed to crankshaft outlet. The oil forms an immiscible mixture with air, thus a two phase flow model should be analyzed using Volume of Fluid (VoF) method in the flow solver. Main findings related to the oil mass flow rate released from the crankshaft outlet reveal that with increasing rotational speed, the mass flow rate from the crankshaft outlet also increases, but with increasing viscosity and decreasing crankshaft-to-oil sump bottom distance, the oil mass flow rate decreases.

Thermal Characterization of Interlayer Microfluidic Cooling of Three-Dimensional Integrated Circuits With Nonuniform Heat Flux

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Yoon Jo Kim ◽  
Yogendra K. Joshi ◽  
Andrei G. Fedorov ◽  
Young-Joon Lee ◽  
Sung-Kyu Lim
Keyword(s):  
Integrated Circuits ◽  
Mass Flow Rate ◽  
Thermal Management ◽  
Mass Flow ◽  
Flow Rate ◽  
Single Phase ◽  
Hot Spot ◽  
Three Dimensional ◽  
Two Phase ◽  
Two Phase Cooling

It is now widely recognized that the three-dimensional (3D) system integration is a key enabling technology to achieve the performance needs of future microprocessor integrated circuits (ICs). To provide modular thermal management in 3D-stacked ICs, the interlayer microfluidic cooling scheme is adopted and analyzed in this study focusing on a single cooling layer performance. The effects of cooling mode (single-phase versus phase-change) and stack/layer geometry on thermal management performance are quantitatively analyzed, and implications on the through-silicon-via scaling and electrical interconnect congestion are discussed. Also, the thermal and hydraulic performance of several two-phase refrigerants is discussed in comparison with single-phase cooling. The results show that the large internal pressure and the pumping pressure drop are significant limiting factors, along with significant mass flow rate maldistribution due to the presence of hot-spots. Nevertheless, two-phase cooling using R123 and R245ca refrigerants yields superior performance to single-phase cooling for the hot-spot fluxes approaching ∼300 W/cm2. In general, a hybrid cooling scheme with a dedicated approach to the hot-spot thermal management should greatly improve the two-phase cooling system performance and reliability by enabling a cooling-load-matched thermal design and by suppressing the mass flow rate maldistribution within the cooling layer.

scholarly journals Development of Hybrid Airlift-Jet Pump with Its Performance Analysis

2018 ◽  
Vol 8 (9) ◽  
pp. 1413 ◽  
Author(s):  
Dan Yao ◽  
Kwongi Lee ◽  
Minho Ha ◽  
Cheolung Cheong ◽  
Inhiug Lee
Keyword(s):  
Boundary Conditions ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Jet Pump ◽  
Two Phase

A new pump, called the hybrid airlift-jet pump, is developed by reinforcing the advantages and minimizing the demerits of airlift and jet pumps. First, a basic design of the hybrid airlift-jet pump is schematically presented. Subsequently, its performance characteristics are numerically investigated by varying the operating conditions of the airlift and jet parts in the hybrid pump. The compressible unsteady Reynolds-averaged Navier-Stokes equations, combined with the homogeneous mixture model for multiphase flow, are used as the governing equations for the two-phase flow in the hybrid pump. The pressure-based methods combined with the Pressure-Implicit with Splitting of Operators (PISO) algorithm are used as the computational fluid dynamics techniques. The validity of the present numerical methods is confirmed by comparing the predicted mass flow rate with the measured ones. In total, 18 simulation cases that are designed to represent the various operating conditions of the hybrid pump are investigated: eight of these cases belong to the operating conditions of only the jet part with different air and water inlet boundary conditions, and the remaining ten cases belong to the operating conditions of both the airlift and jet parts with different air and water inlet boundary conditions. The mass flow rate and the efficiency are compared for each case. For further investigation into the detailed flow characteristics, the pressure and velocity distributions of the mixture in a primary pipe are compared. Furthermore, a periodic fluctuation of the water flow in the mass flow rate is found and analyzed. Our results show that the performance of the jet or airlift pump can be enhanced by combining the operating principles of two pumps into the hybrid airlift-jet pump, newly proposed in the present study.

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

scholarly journals Investigations of mechanical behavior in gear pump using design of software

2014 ◽  
Vol 3 (4) ◽  
pp. 435
Author(s):  
C. Raghunathan ◽  
C. Manoharan
Keyword(s):  
Film Thickness ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Design Of Experiment ◽  
Gear Pump ◽  
Oil Film ◽  
Taguchi Design Of Experiment ◽  
Face Width ◽  
Crank Angle

This research study focused on the various aspects of tribological phenomenon using design of experiments approach, results are analyzed and compared to evaluate the gear performance. Though lot of research work had been carried out on the hydrodynamic gear under static loads, till date no one consider the parameter say stiffness, damping co-efficient, squeeze film effects and the pressure distribution at various crank angle under dynamic load conditions and its effects on inertia forces of gear pump. It covers sinusoidal load, journal speed, face width and mass flow rate with respect to variations in oil film thickness. Frictional test rig was used to measure the frictional force and oil film thickness at various crank angles for every three minutes at an interval of every 15 degree crank angle. The response surface methodology (RSM) analysis shows appreciable increases in respect of performances in mass flow rate, face width, speed and loading against the Taguchi design of experiment results whereas the film thickness is almost same in both RSM and Taguchi design of experiment results. Particular attention is given in this research exertion to learn how the variation in gear dimensions influences the characteristics of the hydrodynamic gear pump. Keywords: Hydrodynamic Gear Pump, Oil Film Thickness, Mathematical Modeling, Taghuchi and RSM, Eddycurrent Cap Sensor.

Predicted performance of a two-phase underwater ramjet with a Laval nozzle

2018 ◽  
Vol 233 (3) ◽  
pp. 937-948
Author(s):  
Jiarui Zhang ◽  
Zhixun Xia ◽  
Liya Huang ◽  
Likun Ma
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Laval Nozzle ◽  
Fluid Model ◽  
Bubbly Flow ◽  
Engine Performance ◽  
Orifice Diameter ◽  
Two Phase ◽  
Convergent Nozzle

To predict engine performance and further instruct the integral engine design, a more reasonable and accurate numerical model of the two-phase underwater ramjet was introduced in this article by considering the bubble formation process. Two-fluid model was used to examine the bubbly flow in the nozzle and its mathematical model was solved by a fourth-order Runge–Kutta method. Subsequently, the influences of vessel velocity, gas mass flow rate, navigational depth, and orifice diameter of the bubble injector on the performance of the engine were discussed. Results show that, compared with convergent nozzle, Laval nozzle is proved to improve the thrust of the engine, especially at relatively high velocity and gas mass flow rate. With the other conditions fixed, there is an optimum vessel velocity for the ramjet, in which maximum thrust is generated. And a smaller orifice diameter always promotes the engine performance, while this promotion is negligible when the orifice diameter is smaller than 1 mm. Besides, increasing backpressure will cause serious performance drop, which means that the the two-phase underwater ramjet is only efficient for shallow depths.

Study of Hybrid Lubrication at the Tooth Contact of a Wormgear Transmission: Part 2—Results and Discussion

1998 ◽  
Vol 120 (1) ◽  
pp. 112-118
Author(s):  
Qin Yuan ◽  
D. C. Sun ◽  
D. E. Brewe
Keyword(s):  
Temperature Distribution ◽  
Film Thickness ◽  
Numerical Solution ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Power Loss ◽  
Oil Film ◽  
Supply Pressure ◽  
Transmission Part

Part 2 begins by describing the numerical solution procedures of the hybrid lubrication problem. Results of the computation are then presented that include the detailed pressure and temperature distribution in the oil film, the required supply pressure for maintaining the prescribed minimum oil film thickness, the fluid friction acting on the worm coil surface, the mass flow rate of supply oil, and the power loss associated with the restrictor flow. The feasibility of the hydrostatically lubricated wormgear transmission is discussed in light of these results.

A vibration probe sensor for mass flow rate measurement of gas-solid two-phase flow

Sensor Review ◽  
2016 ◽  
Vol 36 (2) ◽  
pp. 200-206 ◽  
Author(s):  
Chao Wang ◽  
Heyang Yu ◽  
Ni Zhan ◽  
Xubing Kang ◽  
Jingyu Zhang
Keyword(s):  
Mass Flow Rate ◽  
Natural Frequency ◽  
Mass Flow ◽  
Flow Rate ◽  
Spectral Peak ◽  
Flow Rate Measurement ◽  
Average Amplitude ◽  
Two Phase ◽  
Content Type ◽  
Probe Sensor

Purpose The purpose of this paper is to develop a new vibration probe sensor for measurement of particle mass flow rate in gas–solid two phase flow. Design/methodology/approach A new vibration probe sensor based on polyvinylidene fluoride (PVDF) piezoelectric film is designed. The particle impact model according to Hertz contacting theory is presented. The average amplitude, standard deviation and spectral peak at the natural frequency of the probe (21.2 kHz) of the signals acquired through experiments are chosen as characteristic quantities for further analysis. Findings Through experimental study of relation between three characteristic quantities and the mass flow rate and air flow velocity, a good regularity is found in the average amplitude and the spectral peaks at natural frequency of the probe. According to the particle impact model, the structure of quantitative model is built and parameters of two models are calculated from experimental data. Additionally, tests are made to estimate mass flow rate. The average errors are 5.85 and 4.26 per cent, while the maximum errors are 10.81 and 8.65 per cent. The spectral peak at natural frequency of the probe is more applicable for mass flow rate measurement. Practical implications The sensor designed and the quantitative models established may be used in dilute phase pneumatic conveying lines of coal-fired power plants, cement manufacturing facilities and so on. Originality/value First, the new sensor is designed and the quantitative models are established. Second, the spectral peak at natural frequency of the probe is found that can be used for measurement of mass flow rate.

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