First-Principle Dynamic Modeling of a Linear Micro-Compressor

2013 ◽  
Author(s):  
Mahmoud Alzoubi ◽  
Guanqiu Li ◽  
TieJun Zhang
Keyword(s):  
High Performance ◽  
Electronics Cooling ◽  
First Principle ◽  
Vapor Compression ◽  
Transient Pressure ◽  
Piston Velocity ◽  
Temperature Changes ◽  
Temperature Trends ◽  
Vapor Compression Cooling ◽  
Main Component

Compressor is the main component in the Vapor Compression Cooling cycle (VCC). Comparing with scroll and screw compressors, linear compressors are used in miniature-scale VCC cycle for small and portable applications such as electronics cooling systems. Linear micro-compressors exhibit high performance because they have fewer moving components and less frictional losses than other types. In this paper, a first-principle dynamic model has been developed to characterize the transient pressure, temperature, and fluid flow inside a linear micro-compressor. A theoretical analysis and a parametric study have been performed in this research to reveal the influence of the piston motion profile on the pressure and temperature changes inside the compression chamber. Moreover, the effect of changing piston velocity on the flow rate, pressure and temperature trends has been studied in this research.

scholarly journals Giant multiple caloric effects in charge transition ferrimagnet

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yoshihisa Kosugi ◽  
Masato Goto ◽  
Zhenhong Tan ◽  
Daisuke Kan ◽  
Masahiko Isobe ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Entropy Change ◽  
Vapor Compression ◽  
Cooling Systems ◽  
Environment Friendly ◽  
Temperature Changes ◽  
First Order ◽  
Vapor Compression Cooling ◽  
Future Technologies ◽  
Kbar Pressure

AbstractCaloric effects of solids can provide us with innovative refrigeration systems more efficient and environment-friendly than the widely-used conventional vapor-compression cooling systems. Exploring novel caloric materials is challenging but critically important in developing future technologies. Here we discovered that the quadruple perovskite structure ferrimagnet BiCu3Cr4O12 shows large multiple caloric effects at the first-order charge transition occurring around 190 K. Large latent heat and the corresponding isothermal entropy change, 28.2 J K−1 kg−1, can be utilized by applying both magnetic fields (a magnetocaloric effect) and pressure (a barocaloric effect). Adiabatic temperature changes reach 3.9 K for the 50 kOe magnetic field and 4.8 K for the 4.9 kbar pressure, and thus highly efficient thermal controls are achieved in multiple ways.

scholarly journals Design and Development of Lubricating Material Database and Research on Performance Prediction Method of Machine Learning

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Dan Jia ◽  
Haitao Duan ◽  
Shengpeng Zhan ◽  
Yongliang Jin ◽  
Bingxue Cheng ◽  
...  
Keyword(s):  
Machine Learning ◽  
High Performance ◽  
Prediction Method ◽  
Lubricating Oil ◽  
Physical Parameters ◽  
First Principle ◽  
Vast Number ◽  
First Principle Calculation ◽  
Lubricating Material ◽  
Machine Learning Model

AbstractLong developing period and cumbersome evaluation for the lubricating materials performance seriously jeopardize the successful development and application of any database system in tribological field. Such major setback can be solved effectively by implementing approaches with high throughput calculation. However, it often involves with vast number of output files, which are computed on the basis of first principle computation, having different data format from that of their experimental counterparts. Commonly, the input, storage and management of first principle calculation files and their individually test counterparts, implementing fast query and display in the database, adding to the use of physical parameters, as predicted with the performance estimated by first principle approach, may solve such setbacks. Investigation is thus performed for establishing database website specifically for lubricating materials, which satisfies both data: (i) as calculated on the basis of first principles and (ii) as obtained by practical experiment. It further explores preliminarily the likely relationship between calculated physical parameters of lubricating oil and its respectively tribological and anti-oxidative performance as predicted by lubricant machine learning model. Success of the method facilitates in instructing the obtainment of optimal design, preparation and application for any new lubricating material so that accomplishment of high performance is possible.

High-Performance Single-Electron Transistor Based on Metal–Organic Complex of Thiophene: First Principle Study

2017 ◽  
Vol 64 (11) ◽  
pp. 4628-4635 ◽  
Author(s):  
Anu ◽  
Archana Sharma ◽  
Md. Shahzad Khan ◽  
Anurag Srivastava ◽  
Mushahid Husain ◽  
...  
Keyword(s):  
High Performance ◽  
Single Electron ◽  
Single Electron Transistor ◽  
First Principle ◽  
Organic Complex ◽  
Metal Organic Complex ◽  
Metal Organic

scholarly journals Ketone bodies – causes and effects of their increased presence in cows' body fluids: A review

2021 ◽  
pp. 1492-1503
Author(s):  
Piotr Guliński
Keyword(s):  
Dairy Cows ◽  
High Performance ◽  
Clinical Symptoms ◽  
Ketone Bodies ◽  
Good Condition ◽  
Body Fluids ◽  
Protein Ratio ◽  
Loss Of Appetite ◽  
Point Body ◽  
Main Component

Ketosis is the most common metabolic disease in high-performance dairy cows during the first 6-8 weeks of lactation. Its main symptoms include an excessive amount of so-called ketone bodies in a cow's body fluids. Ketone bodies consist of β-hydroxybutyric acid (βHBA), acetoacetic acid, and acetone. βHBA is the main component with its share of the total volume of ketone bodies in the blood of about 70%. Clinical symptoms of ketosis in cows include loss of appetite, preference for forage to concentrated feed, and acetone odor in their mouth and urine. Those symptoms are accompanied by a production drop, an increase of concurrent illness (mastitis, metritis, and displaced abomasum), and poor reproductive performance. One of the ketosis characteristic effects is an increase in the level of fat in milk (>5%), while protein levels decrease (<2.9%). In the case of subclinical ketosis (SCK), the fat–protein ratio in milk is increased to above 1.4:1. The current consensus for SCK is to consider a cutoff point of βHBA to be at least 1.2 mmol/L in blood plasma. Ketosis prevention is based on keeping perinatal cows in good condition, that is, with around 3.5 points in the five-point body condition scoring, carefully balancing food doses during the first 2 months of lactation with the correct energy–protein ratio. Glucose precursor products should be administered orally, in particular to at-risk herds. Ketosis occurs in 7-14% on average of the total number of cows in a herd. In general, data on the prevalence of SCK vary considerably, depending on their source. Moreover, the problem is mostly observed in poorly-fed animals with high milk production potential. The objectives of this review are to reveal the current situation of ketosis prevalence, the possibility of diagnosis, consequences in dairy cows and to provide some recommendations for ketosis treatment and prevention.

Novel Fluorescent Visualization Method to Characterize Transport Properties in Micro/Nano Heat Pipe Wick Structures

2009 ◽  
Author(s):  
Pramod Chamarthy ◽  
H. Peter J. de Bock ◽  
Boris Russ ◽  
Shakti Chauhan ◽  
Brian Rush ◽  
...  
Keyword(s):  
Heat Pipe ◽  
High Performance ◽  
Gravitational Force ◽  
Driving Forces ◽  
Electronics Cooling ◽  
Heat Pipes ◽  
High Permeability ◽  
Permeability Characteristics ◽  
Wick Structure ◽  
Initial Results

Heat pipes have been gaining a lot of popularity in electronics cooling applications due to their ease of operation, reliability, and high effective thermal conductivity. An important component of a heat pipe is the wick structure, which transports the condensate from condenser to evaporator. The design of wick structures is complicated by competing requirements to create high capillary driving forces and maintain high permeability. While generating large pore sizes will help achieve high permeability, it will significantly reduce the wick’s capillary performance. This study presents a novel experimental method to simultaneously measure capillary and permeability characteristics of the wick structures using fluorescent visualization. This technique will be used to study the effects of pore size and gravitational force on the flow-related properties of the wick structures. Initial results are presented on wick samples visually characterized from zero to nine g acceleration on a centrifuge. These results will provide a tool to understand the physics involved in transport through porous structures and help in the design of high performance heat pipes.

Miniature Vapor Compression Refrigeration Systems for Active Cooling of High Performance Computers

2001 ◽  
Author(s):  
Ali Heydari ◽  
Kathy Russell
Keyword(s):  
Heat Exchanger ◽  
High Performance ◽  
Capillary Tube ◽  
New Technology ◽  
Mathematical Formulation ◽  
Coefficient Of Performance ◽  
Simulation Program ◽  
Vapor Compression ◽  
Refrigeration System ◽  
System Components

Abstract A small refrigeration system for cooling of computer system components is evaluated. A thermodynamic model describing the performance of the cycle along with a computer simulation program is developed to evaluate its performance. The refrigeration system makes use of a miniature reciprocating vapor compression compressor. Due to space limitations in some high performance computer servers, a miniature refrigeration system composed of a compressor, capillary tube, a compact condenser, and a cold-plate evaporator heat exchanger are used. Mathematical multi-zone formulation for modeling thermal-hydraulic performance of heat exchanger for the condenser and evaporator are presented. The throttling device is a capillary tube and there is presented a mathematical formulation for predicting refrigerant mass flow rate through the throttling device. A physically based efficiency formulation for simulating the performance of the miniature compressor is used. An efficient iterative numerical scheme with allowance for utilization of various refrigerants is developed to solve the governing system of equations. Using the simulation program, the effects of parameters such as the choice of working refrigerant, evaporating and condensing temperatures on system components and overall efficiency of system are studied. In addition, a RAS (reliability, availability and serviceability) discussion of the proposed CPU-cooling refrigeration solution is presented. The results of analysis show that the new technology not only overcomes many shortcomings of the traditional fan-cooled systems, but also has the capacity of increasing the cooling system’s coefficient of performance.

scholarly journals Field measurement of ground temperatures in Bandung: devices and the results of measurement

2020 ◽  
Vol 200 ◽  
pp. 02009
Author(s):  
Muhammad Nur Fajri Alfata ◽  
Amalia Nurjannah
Keyword(s):  
Temperature Sensor ◽  
Field Measurement ◽  
Ground Temperature ◽  
Passive Cooling ◽  
Temperature Profiles ◽  
Temperature Changes ◽  
Ground Temperatures ◽  
Different Depths ◽  
Measurement Devices ◽  
Main Component

Ground cooling is considered to be one of the passive cooling strategies in buildings although its application is rarely found in Indonesia. Effectiveness of this strategy depend on the ground temperature profiles. Meanwhile, comprehensive data of ground temperature as a basis of design for ground cooling are still rarely found in Indonesia. This research aims to develop the measurement devices for collecting ground temperatures data and to investigate the ground temperatures in different depths (i.e., 1m, 2m, …, 9m). For measurement, an instrumentation system was developed with the main component of Arduino Mega 2560 as microcontroller. T-type thermocouples with diameter of 0, 5mm mounted in the metal cones were used as the temperature sensor and placed at the different depths. The field measurement was conducted from August to November 2019 in Bandung, West Java, Indonesia. This study demonstrated that the developed instrument system had good performance both in measuring and data acquisition. Model equation was developed to predict the ground temperature at certain depth regardless ground materials and humidity level. The results indicated that the ground temperature significantly lower to 5m-depth. However, the reduction of the temperature after 5m was not significant; the deeper the ground, the temperature changes are negligible.

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