scholarly journals Simulation and Evaluation on The Dynamic Performance of a Cryogenic Turbo-Based Reverse Brayton Refrigerator

2019 ◽  
Vol 9 (3) ◽  
pp. 531 ◽  
Author(s):  
Shanju Yang ◽  
Zhan Liu ◽  
Bao Fu
Keyword(s):  
Energy Efficiency ◽  
Heat Exchanger ◽  
High Speed ◽  
Dynamic Performance ◽  
Simulation Method ◽  
Practical Applications ◽  
Improve Energy Efficiency ◽  
Dynamic Simulation Model ◽  
Simulation And Evaluation ◽  
Cryogenic Refrigerator

In this study, a cryogenic turbo-based refrigerator, with high-speed foil gas bearing turboexpander and plate-fin heat exchanger, was presented. For the cooling process of a cryogenic refrigerator is long and complex, the efficient simulation of the dynamic performance is vital for its evaluation and operation. It is difficult to achieve this purpose. Because the cryogenic refrigerator will go through great temperature changes, resulting in dynamic performances of components going to complexity. In this article, the turboexpander was simulated using CFX, and the matching models with expansion works of consumption and utilization were unified and modified. With numerical calculation of heat exchanger, the dynamic simulation model of the refrigerator was improved via MATLAB code. The calculation method of the required input energy of the refrigerator in cooling processes was proposed based on the simulation and integration. The energy efficiency and economy cost of the refrigerator were evaluated under different operation modes. The refrigerator with a motor was more stable than the one with a blower. The refrigerator was tested under different conditions, the results of which agreed well with simulation data. The simulation method is efficient to serve practical applications, improve energy efficiency and reduce costs.

scholarly journals The Numerical Simulation of the Airflow Distribution and Energy Efficiency in Data Centers with Three Types of Aisle Layout

2019 ◽  
Vol 11 (18) ◽  
pp. 4937 ◽  
Author(s):  
Jing Ni ◽  
Bowen Jin ◽  
Shanglei Ning ◽  
Xiaowei Wang
Keyword(s):  
Energy Efficiency ◽  
Power Consumption ◽  
Air Conditioning ◽  
Data Centers ◽  
Simulation Method ◽  
Cooling Capacity ◽  
Energy Utilization ◽  
Improve Energy Efficiency ◽  
Electricity Cost ◽  
Airflow Distribution

The energy consumption of fast-growing data centers is drawing attentions from not only energy organizations and institutions all over the world, but also charity groups, such as Greenpeace, and research shows that the power consumption of air conditioning makes up a large proportion of the electricity cost in data centers. Therefore, more detailed investigations of air conditioning power consumption are warranted. Three types of airflow distributions with different aisle layouts (the open aisle, the closed cold aisle, and the closed hot aisle) were investigated with Computational Fluid Dynamics (CFD) methods in a typical data center of four rows of racks in this study. To evaluate the results of thermal and bypass phenomenon, the temperature increase index (β) and the energy utilization index (ηr) were used. The simulations show that there is a better trend of the β index and ηr index both closed cold aisle and closed hot aisle compared with free open aisle. Especially with high air flow rate, the β index decreases and the ηr index increases considerably. Moreover, the results prove the closed aisles (both closed cold aisle and closed hot aisle) can not only significantly improve the airflow distribution, but also reduce the mixture of cold and heat flow, and therefore improve energy efficiency. In addition, it proves the design of the closed aisles can meet the increasing density of installations and our simulation method could evaluate the cooling capacity easily.

scholarly journals Dynamic Simulation of Crank-group Driving Mechanism with Clearance

2016 ◽  
Vol 12 (02) ◽  
pp. 35
Author(s):  
Yansong Liu ◽  
Jujiang Cao
Keyword(s):  
Angular Velocity ◽  
Dynamic Simulation ◽  
Dynamic Characteristics ◽  
Dynamic Performance ◽  
Driving Mechanism ◽  
Practical Applications ◽  
Dynamic Simulation Model ◽  
Processing Errors ◽  
Stiffness And Damping ◽  
D Model

The crank-group driving mechanism includes a group of redundant constraints. This mechanism can move as a driving mechanism under ideal conditions, but it may be stuck because of the processing errors in practical applications. So, some clearances are reserved between the pin hole and the pin to ensure that the crank-group driving mechanism can achieve normal movement, but these clearances inevitably affect the dynamic performance of the output member. In this paper, the dynamic simulation model of the crank-group driving mechanism is established by NX/Motion Simulation which is based on the 3-D model of planar link mechanism. The comparative analysis is made about the dynamic characteristics of the mechanism which is influenced by different clearances, different angular velocity, different damping, and make a qualitative analysis how the clearances affects the dynamic performance of the output member. The simulation results also show that appropriately increasing the angular velocity, increasing stiffness and damping of the components can effectively inhibit the adverse influences of clearance on the dynamic characteristics of the mechanism.

scholarly journals Increasing of Energy Efficiency of Spindles with Fluid Bearings

2017 ◽  
Vol 11 (3) ◽  
pp. 204-209
Author(s):  
Dmytro Fedorynenko ◽  
Serhii Sapon ◽  
Sergiy Boyko ◽  
Anastasiia Urlina
Keyword(s):  
Energy Efficiency ◽  
High Speed ◽  
Integrated System ◽  
Theoretical Research ◽  
Efficiency Gain ◽  
Power Losses ◽  
Relay Control ◽  
Improve Energy Efficiency ◽  
Spindle Unit ◽  
Grinding Machine

AbstractPromising ways of energy efficiency gain of spindles with fluid flow bearings are offered. New design of journal hybrid flow bearing which contains spherical bearing pockets and adjustable valves with relay control system is offered to improve energy efficiency of spindle units of machine tools. To reduce power losses of fluid bearings at high speed special lubrication based on water with integrated system of corrosion protection is offered. Results of theoretical research of energy consumption of grinding machine tool with a new design of spindle hybrid bearings are presented. Power losses of the spindle unit with both new design and base design of journal bearings are assessed. Effectiveness of new design of spindle hybrid bearings at high operating speeds is shown.

scholarly journals A non-linear control method for active magnetic bearings with bounded input and output

2020 ◽  
Vol 11 (4) ◽  
pp. 2154
Author(s):  
Danh Huy Nguyen ◽  
Lam Tung Nguyen ◽  
Duc Chinh Hoang
Keyword(s):  
High Speed ◽  
Control Method ◽  
Dynamic Performance ◽  
Input Saturation ◽  
Magnetic Bearing ◽  
Control Input ◽  
Practical Applications ◽  
Input And Output ◽  
Output Constraints ◽  
Control Objective

Magnetic bearing is well-known for its advantage of reducing friction in rotary machines and is placing conventional bearings where high-speed operations and cleanliness are essential. It can be shown that the AM is a nonlinear system due to the relation between the magnetic force and current/rotor displacement. In this paper, a mathematical model of a 4-DOF AMB supported by four dual electric magnets is presented. The control objective is placed in a view of control input saturation and output limitation that are meaningful aspect in practical applications. Backstepping algorithm based control strategy is then adopted in order to achieve the high dynamic performance of the bearing. The control is designed in such a way that it takes input and output constraints into account by flexibly using hyperbolic tangent and barrier Lyapunov functions. Informative simulation studies are carried out to understand the operations of the machine and evaluate the controller quality.

Sizing Optimization of Pneumatic Actuation Systems Through Operating Point Analysis

2020 ◽  
Vol 143 (5) ◽  
Author(s):  
Vinícius Vigolo ◽  
Victor Juliano De Negri
Keyword(s):  
Energy Efficiency ◽  
Dynamic Performance ◽  
Operating Point ◽  
Pneumatic Actuation ◽  
Actuation System ◽  
Operating Region ◽  
Point Analysis ◽  
Dynamic Simulation Model ◽  
Good Energy ◽  
Actuation Systems

Abstract This paper reports a study on the static and dynamic behavior of pneumatic actuation systems, resulting in a comprehensive view of the influence of the system parameters on the energy efficiency and dynamic performance. The operating point approach based on the steady-state analysis of a pneumatic actuation system is used for developing analytical expressions to describe the relationship between the piston diameter and the system performance, including displacement time, stroke end velocity, and energy efficiency. The validity of the proposed equations is demonstrated by comparison with results from a test rig. Sensitivity analysis using a nonlinear dynamic simulation model indicated that a specific operating region exists, where good energy efficiency and the maximum dynamic performance are achieved. Moreover, the results show that an oversized system becomes more inefficient in both energetic and dynamic aspects. The results obtained provide a very consistent foundation for developing a method for pneumatic system sizing.

COMPUTER SIMULATION OF FLOW IN CORRUGATED CHANNEL OF PLATE HEAT EXCHANGER

2020 ◽  
pp. 51-58
Author(s):  
Л. А. Кущев ◽  
В. Н. Мелькумов ◽  
Н. Ю. Саввин
Keyword(s):  
Computer Simulation ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
High Speed ◽  
Exchange Process ◽  
Plate Heat Exchanger ◽  
System Stability ◽  
Plate Heat ◽  
Corrugated Channel ◽  
Heat Exchange Process

Постановка задачи. Рассматривается теплообменный процесс, протекающий в модифицированном гофрированном межпластинном канале интенсифицированного пластинчатого теплообменного аппарата с повышенной турбулизацией теплоносителя. Необходимо разработать компьютерную модель движения теплоносителя в диапазоне скоростей 0,1-1,5 м/с и определить коэффициент турбулизации пластинчатого теплообменника. Результаты. Приведены результаты компьютерного моделирования движения теплоносителя в межпластинном гофрированном канале оригинального пластинчатого теплообменного аппарата с помощью программного комплекса Аnsys . Определены критерии устойчивости системы. Выполнено 3 D -моделирование канала, образуемого гофрированными пластинами. При исследовании процесса турбулизации были рассмотрены несколько скоростных режимов движения теплоносителя. Определен коэффициент турбулизации Tu, %. Выводы. В результате компьютерного моделирования установлено увеличение коэффициента теплопередачи К, Вт/(м ℃ ) за счет повышенной турбулизации потока, что приводит к снижению металлоемкости и уменьшению стоимости теплообменного оборудования. Statement of the problem. The heat exchange process occurring in a modified corrugated interplate channel of an intensified plate heat exchanger with an increased turbulence of the heat carrier is discussed. A computer model of the coolant movement in the speed range of 0.1-1.5 m/s is developed and the turbulence coefficient of the plate heat exchanger is determined. Results. The article presents the results of computer modeling of the coolant movement in the interplate corrugated channel of the original plate heat exchanger using the Ansys software package. The criteria of system stability are defined. 3D modeling of the channel formed by corrugated plates is performed. In the study of the process of turbulence several high-speed modes of movement of the coolant were considered. The turbulence coefficient Tu, % is determined. Conclusions. As a result of computer simulation, an increase in the heat transfer coefficient K, W/(m ℃) was found due to an increased turbulization of the flow, which leads to a decrease in metal consumption and a decrease in the cost of heat exchange equipment.

Recent Patents on the Angular Contact Ball Bearing of High-Speed Motorized Spindle

2020 ◽  
Vol 13 ◽  
Author(s):  
Yudong Bao ◽  
Linkai Wu ◽  
Yanling Zhao ◽  
Chengyi Pan
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Rapid Development ◽  
Ceramic Materials ◽  
Development Trend ◽  
Numerical Control ◽  
Angular Contact Ball Bearing ◽  
Practical Applications ◽  
High Speed Cutting ◽  
Advantages And Disadvantages

Background:: Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers, The performance of the bearing directly affects the machining efficiency of the machine tool, Obtaining a higher value is the direction of its research and development. Objective:: By analyzing the research achievements and patents of electric spindle angular contact bearings, summarizing the development trend provides a reference for the development of electric spindle bearings. Methods:: Through the analysis of the relevant technology of the electric spindle angular contact ball bearing, the advantages and disadvantages of the angular contact ball bearing are introduced, and the research results are combined with the patent analysis. Results:: With the rapid development of high-speed cutting and numerical control technology and the needs of practical applications, the spindle requires higher and higher speeds for bearings. In order to meet the requirements of use, it is necessary to improve the bearing performance by optimizing the structure size and improving the lubrication conditions. Meanwhile, reasonable processing and assembly methods will also have a beneficial effect on bearing performance. Conclusion:: With the continuous deepening of bearing technology research and the use of new structures and ceramic materials has made the bearing's limit speed repeatedly reach new highs. The future development trend of high-speed bearings for electric spindles is environmental protection, intelligence, high speed, high precision and long life.

Dynamic Performance of High-Speed Electric Multiple Unit within Multi-Body System Simulation

2019 ◽  
Vol 12 (4) ◽  
pp. 339-349
Author(s):  
Junguo Wang ◽  
Daoping Gong ◽  
Rui Sun ◽  
Yongxiang Zhao
Keyword(s):  
High Speed ◽  
Rapid Development ◽  
Dynamic Performance ◽  
Body System ◽  
High Speed Railway ◽  
Evaluation Indexes ◽  
Actual Operation ◽  
Multiple Unit ◽  
The Stability ◽  
Multi Body

Background: With the rapid development of the high-speed railway, the dynamic performance such as running stability and safety of the high-speed train is increasingly important. This paper focuses on the dynamic performance of high-speed Electric Multiple Unit (EMU), especially the dynamic characteristics of the bogie frame and car body. Various patents have been discussed in this article. Objective: To develop the Multi-Body System (MBS) model of EMU, verify whether the dynamic performance meets the actual operation requirements, and provide some useful information for dynamics and structural design of the proposed EMU. Methods: According to the technical characteristics of a typical EMU, a MBS model is established via SIMPACK, and the measured data of China high-speed railway is taken as the excitation of track random irregularity. To test the dynamic performance of the EMU, including the stability and safety, some evaluation indexes such as wheel-axle lateral forces, wheel-axle lateral vertical forces, derailment coefficients and wheel unloading rates are also calculated and analyzed in detail. Results: The MBS model of EMU has better dynamic performance especially curving performance, and some evaluation indexes of the stability and safety have also reached China’s high-speed railway standards. Conclusion: The effectiveness of the proposed MBS model is verified, and the dynamic performance of the MBS model can meet the design requirements of high-speed EMU.

scholarly journals Prognostic Assessment of the Performance Parameters for the Industrial Diesel Engines Operated with Microalgae Oil

2021 ◽  
Vol 13 (11) ◽  
pp. 6482
Author(s):  
Sergejus Lebedevas ◽  
Laurencas Raslavičius
Keyword(s):  
Energy Efficiency ◽  
Diesel Engine ◽  
High Speed ◽  
Performance Parameters ◽  
Prognostic Assessment ◽  
High Speed Diesel ◽  
Microalgae Oil ◽  
The Difference ◽  
Smoke Opacity ◽  
Efficiency Indicators

A study conducted on the high-speed diesel engine (bore/stroke: 79.5/95.5 mm; 66 kW) running with microalgae oil (MAO100) and diesel fuel (D100) showed that, based on Wibe parameters (m and φz), the difference in numerical values of combustion characteristics was ~10% and, in turn, resulted in close energy efficiency indicators (ηi) for both fuels and the possibility to enhance the NOx-smoke opacity trade-off. A comparative analysis by mathematical modeling of energy and traction characteristics for the universal multi-purpose diesel engine CAT 3512B HB-SC (1200 kW, 1800 min−1) confirmed the earlier assumption: at the regimes of external speed characteristics, the difference in Pme and ηi for MAO100 and D100 did not exceeded 0.7–2.0% and 2–4%, respectively. With the refinement and development of the interim concept, the model led to the prognostic evaluation of the suitability of MAO100 as fuel for the FPT Industrial Cursor 13 engine (353 kW, 6-cylinders, common-rail) family. For the selected value of the indicated efficiency ηi = 0.48–0.49, two different combinations of φz and m parameters (φz = 60–70 degCA, m = 0.5 and φz = 60 degCA, m = 1) may be practically realized to achieve the desirable level of maximum combustion pressure Pmax = 130–150 bar (at α~2.0). When switching from diesel to MAO100, it is expected that the ηi will drop by 2–3%, however, an existing reserve in Pmax that comprises 5–7% will open up room for further optimization of energy efficiency and emission indicators.

scholarly journals A Component-Sizing Methodology for a Hybrid Electric Vehicle Using an Optimization Algorithm

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3147
Author(s):  
Kiyoung Kim ◽  
Namdoo Kim ◽  
Jongryeol Jeong ◽  
Sunghwan Min ◽  
Horim Yang ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Electric Vehicle ◽  
Optimization Algorithm ◽  
Hybrid Electric Vehicle ◽  
New Technologies ◽  
New Technology ◽  
Dynamic Performance ◽  
Minimum Principle ◽  
Component Sizing ◽  
Hybrid Electric

Many leading companies in the automotive industry have been putting tremendous effort into developing new powertrains and technologies to make their products more energy efficient. Evaluating the fuel economy benefit of a new technology in specific powertrain systems is straightforward; and, in an early concept phase, obtaining a projection of energy efficiency benefits from new technologies is extremely useful. However, when carmakers consider new technology or powertrain configurations, they must deal with a trade-off problem involving factors such as energy efficiency and performance, because of the complexities of sizing a vehicle’s powertrain components, which directly affect its energy efficiency and dynamic performance. As powertrains of modern vehicles become more complicated, even more effort is required to design the size of each component. This study presents a component-sizing process based on the forward-looking vehicle simulator “Autonomie” and the optimization algorithm “POUNDERS”; the supervisory control strategy based on Pontryagin’s Minimum Principle (PMP) assures sufficient computational system efficiency. We tested the process by applying it to a single power-split hybrid electric vehicle to determine optimal values of gear ratios and each component size, where we defined the optimization problem as minimizing energy consumption when the vehicle’s dynamic performance is given as a performance constraint. The suggested sizing process will be helpful in determining optimal component sizes for vehicle powertrain to maximize fuel efficiency while dynamic performance is satisfied. Indeed, this process does not require the engineer’s intuition or rules based on heuristics required in the rule-based process.

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