scholarly journals The Effect of the Cooling Process on the Crystalline Morphology and Dielectric Properties of Polythene

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2791
Author(s):  
Guang Yu ◽  
Boyang Yu
Keyword(s):  
Space Charge ◽  
Cooling Water ◽  
Dielectric Constants ◽  
Air Cooling ◽  
Water Cooling ◽  
Crystalline Morphology ◽  
Cooling Process ◽  
Experimental Frequency ◽  
Frequency Spectra ◽  
Two Samples

In this study, LDPE samples were prepared by melt blending with different cooling processes, which were natural air cooling, rapid air cooling, water cooling and oil cooling, respectively. According to polarization microscope (PLM) and differential scanning calorimeter (DSC) tests of these four low-density polyethylene (LDPE) samples, the effect of different cooling processes on polythene crystalline morphology could be studied. According to conductivity, dielectric frequency spectra and space charge tests, the effect of crystalline morphology on dielectric macroscopic properties could be explored. The microstructure characteristic results indicated the cooling medium significantly affected polythene crystalline morphology. When the samples were produced with natural air cooling, the crystalline grain size was large. On the other hand, after rapid air cooling, water cooling and oil cooling processes, the samples’ crystalline grain dispersed uniformly, and the grain sizes were lower. The space charge testing results indicate the samples produced with water cooling and oil cooling processes restrained the electrode injection in the process of pressurization. During short-circuits, the rates of charge release of these two samples were fast, and the remaining space charges were fewer. The conductivity and dielectric frequency spectra testing results indicated the conductivities of samples produced with water cooling and oil cooling processes were both less than those of samples produced with a natural air cooling process. Besides, with increasing experimental frequency, the relative dielectric constants of all testing samples decreased. Among them, the relative dielectric constant of the LDPE sample with the natural air cooling process was the largest. However, the crystalline structures of samples produced with rapid air cooling and water cooling processes were close, which restrained the movement of polymer macromolecule chains. Thus, the dielectric constants were lower. Additionally, because of the influence of relaxation polarization and dipole polarization, the dielectric losses of LDPE with water cooling and oil cooling processes increased to varying degrees.

The Effect of Cooling Process on the Microstructure and Electrical Transport Properties of AgSbTe2 Compound

2013 ◽  
Vol 743-744 ◽  
pp. 59-64
Author(s):  
Liang Wei Fu ◽  
Jun You Yang ◽  
Ye Xiao ◽  
Jiang Ying Peng ◽  
Ming Yang Zhang
Keyword(s):  
Electrical Resistivity ◽  
Transport Properties ◽  
Liquid Nitrogen ◽  
Electrical Transport ◽  
Cooling Water ◽  
Air Cooling ◽  
X Ray Diffraction ◽  
Cooling Process ◽  
Electrical Transport Properties ◽  
Apparent Influence

AgSbTe2compounds have been synthesized via melting and subsequent cooling processes. The effect of cooling process, from air-cooling, water quenching to liquid nitrogen-quenching, on the microstructure and the electrical transport properties of AgSbTe2has been investigated by means of powder X-ray diffraction, electron microscope, electrical resistivity, and Hall coefficient measurements. It has been found that the cooling process has apparent influence on the microstructure and corresponding electrical properties. The phase components and morphology changed as the cooling process altered. The electrical resistivity and the Seebeck coefficient of the as-prepared samples increased from air-cooled to liquid nitrogen-quenched sample.

Design of Cooling Water Scheme of Gas Compressing Station in West-to-East Gas Pipeline

2014 ◽  
Vol 577 ◽  
pp. 580-583
Author(s):  
Hong Tao Li ◽  
Zhan Qiang Xu ◽  
Ben Rui Zhu
Keyword(s):  
Frequency Conversion ◽  
High Efficiency ◽  
Selection Process ◽  
Cooling Water ◽  
Economic Benefits ◽  
Gas Pipeline ◽  
Air Cooling ◽  
Water Cooling ◽  
Long Distance ◽  
First Choice

This document focuses on motors and frequency conversion equipments of stations of West-to-East Gas Pipeline, and introduces the present main cooling ways. Against water consumption, power consumption, and other economical index, analyze the selection process of cooling scheme in engineering design. Compare with the cost, workload of operation and maintenance of water cooling, air cooling and motor cooling. The result shows that water cooling is practicable in West-to-East Gas Pipeline and has validated in the established engineering. The method of scheme comparison proposed by this paper provides a reference for subsequent design.With the development of electronics technology, medium voltage high power frequency conversion speed regulation technology is increasingly mature. The technology that frequency conversion motor drives compressor unit has been gradually used in the long distance pipeline pressure field of oil and gas under the condition of reliable power supply, to replace the traditional gas turbine, and becomes the first choice of the pressurization equipment of the long distance pipeline, because of advantages of high technology, high efficiency, energy conservation and environment protection, economic benefits and so on[1-3].Stations of West-to-East Gas Pipeline are usually electrical driven. When the compressors operate, motors and frequency converters will produce large amounts of heat, which affects running state and equipment life. So choosing the economic and technological cooling water scheme is important for stations and the whole network to operate safely and stably[4-6].

Effect of Cooling Mode on Properties of a Cast Zinc Alloy

2013 ◽  
Vol 690-693 ◽  
pp. 66-69 ◽  
Author(s):  
Fei Zhang ◽  
Jin Gui Wan
Keyword(s):  
Material Properties ◽  
Cooling Water ◽  
Zinc Alloy ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Mode ◽  
Comprehensive Properties ◽  
Alloy Material

In order to explore the best way of zinc alloy cooling, respectively adopting air cooling, water cooling, oil cooling and cooling in the furnace, to study its influence on the zinc alloy material properties. The results show that the oil cooling mode can improve the comprehensive properties of zinc alloy.

Heat Transfer Coefficient Prediction by FEM in the Hot Strip Rolling

2011 ◽  
Vol 415-417 ◽  
pp. 1391-1394
Author(s):  
Rui Bin Mei ◽  
Chang Sheng Li ◽  
Xiang Hua Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Temperature Distribution ◽  
Rolling Process ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Process ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip

It is necessary to know the heat transfer intensity for predicting temperature distribution in the hot strip rolling process. The HTC (heat transfer coefficient) was usually obtained by the experiments and mathematical model. In this paper the HTC prediction was discussed based on the measured or target temperature by the proposed finite element method (FEM). The temperature evolution and HTC in the hot strip rolling process according to a certain plant were analyzed by the iteration calculation. The result shows that the HTC between strip and work roll was much more than the value in the air cooling and water cooling process. Furthermore, the HTC value is lower in the air cooling process compared with that of water cooling. The maximum and minimum value of HTC were about 1.5×105 (W/m2.K) and 80(W/m2.K) respectively. The temperature in the rough rolling according to the predicted HTC has been solved and the calculated results have a good agreement to the meausred value. Therefore, the research could be used to control the temperature distribution accurately and optimize the parameters.

High Performance Loop Heat Pipe With Flat Evaporator for Energy-Saving Cooling Systems of Supercomputers

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Zhi Hu Xue ◽  
Wei Qu ◽  
Ming Hui Xie
Keyword(s):  
Heat Load ◽  
High Performance ◽  
Operating Temperature ◽  
Cooling Water ◽  
Working Fluid ◽  
Air Cooling ◽  
Water Cooling ◽  
Test Results ◽  
Central Processing ◽  
Flat Evaporator

Abstract Two high performance loop heat pipes (LHPs) are developed for direct cooling of the chips in supercomputer. The two LHPs using flat evaporator are: one called water-cooling LHP and another one called air-cooling LHP. The working fluid of LHP is ammonia. The water-cooling LHP can work well at a heat load up to 663 W and air-cooling LHP can work well at a heat load up to 513 W. The two LHPs applying to the real computer servers are realized and tested. The server test results with water-cooling LHP have shown that the operating temperature of central processing units (CPUs) can be controlled to about 67 °C to ensure the reliable operating and acceptable level for electronic chips, even at condenser-cooling water temperature of 40 °C with low water flowrate of 0.055 m3/h. The server test results with air-cooling LHP have shown that the operating temperature of CPUs can be controlled to about 51 °C even at condenser-cooling wind temperature of 30 °C with wind flowrate of 41.88 m3/h.

scholarly journals Optimization of Cascade Cooling System Based on Lithium Bromide Refrigeration in the Polysilicon Industry

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1681
Author(s):  
Shutong Yang ◽  
Youlei Wang ◽  
Yufei Wang
Keyword(s):  
Annual Cost ◽  
Load Distribution ◽  
Heat Load ◽  
Waste Heat ◽  
Cooling System ◽  
Cooling Water ◽  
Total Annual Cost ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Methods

Cascade cooling systems containing different cooling methods (e.g., air cooling, water cooling, refrigerating) are used to satisfy the cooling process of hot streams with large temperature spans. An effective cooling system can significantly save energy and costs. In a cascade cooling system, the heat load distribution between different cooling methods has great impacts on the capital cost and operation cost of the system, but the relative optimization method is not well established. In this work, a cascade cooling system containing waste heat recovery, air cooling, water cooling, absorption refrigeration, and compression refrigeration is proposed. The objective is to find the optimal heat load distribution between different cooling methods with the minimum total annual cost. Aspen Plus and MATLAB were combined to solve the established mathematical optimization model, and the genetic algorithm (GA) in MATLAB was adopted to solve the model. A case study in a polysilicon enterprise was used to illustrate the feasibility and economy of the cascade cooling system. Compared to the base case, which only includes air cooling, water cooling, and compression refrigeration, the cascade cooling system can reduce the total annual cost by USD 931,025·y−1 and save 7,800,820 kWh of electricity per year. It also can recover 3139 kW of low-grade waste heat, and generate and replace a cooling capacity of 2404 kW.

An experimental analysis of the cooling constant computation

2021 ◽  
Vol 57 (2) ◽  
pp. 025001
Author(s):  
J E M Perea Martins
Keyword(s):  
Experimental Data ◽  
Water Temperature ◽  
Experimental Analysis ◽  
Electronic System ◽  
Water Cooling ◽  
Cooling Process ◽  
Data Set ◽  
Theoretical Methods ◽  
Electronic Instrumentation

Abstract This work presents the design of an inexpensive electronic system to measure water temperature and generate an experimental data set used to verify the fitting between experimental and theoretical curves of a water-cooling process. The cooling constant is computed with three different theoretical methods to check their efficiency and this approach allows the association of theoretical and experimental aspects of physics, mathematics and electronic instrumentation, which can motivate interesting discussions in the classroom.

scholarly journals Effects of deformation on the microstructure of a Ti-V microalloyed steel in the phase transition region

2004 ◽  
Vol 57 (4) ◽  
pp. 303-311
Author(s):  
Wiliam Regone ◽  
Sérgio Tonini Button
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Transition Region ◽  
Microstructural Evolution ◽  
Microalloyed Steel ◽  
Hot Forging ◽  
Microalloyed Steels ◽  
Air Cooling ◽  
Water Cooling ◽  
Phase Transition Region

Microalloyed steels are used in the forging of many automotive parts like crankshafts and connecting rods. They are hot worked in a sequence of stages that includes the heating to the soaking temperature, followed by forging steps, and finally the controlled cooling to define the microstructure and mechanical properties. In this work it was investigated the thermomechanical behavior and the microstructural evolution of a Ti-V microalloyed steel in the phase transition region. Torsion tests were done with multiple steps with true strain equal to 0.26 in each step. After each torsion step the samples were continuous cooled for 15 seconds to simulate hot forging conditions. These tests provided results for the temperature at the beginning of the phase transformation, and allowed to analyze the microstructural changes. Also, workability tests were held to analyze the microstructural evolution by optical and scanning electron microscopy. Results from the torsion tests showed that the temperature for the beginning of phase transformation is about 700 ºC. Workability tests held at 700 ºC followed by water-cooling presented microstructures with different regions: strain hardened, and static and dynamic recrystallized. Workability tests at 700 ºC followed by air-cooling showed a complex microstructure with ferrite, bainite and martensite, while tests at 650 and 600 ºC followed by water-cooling showed a microstructure with allotriomorphic ferrite present in the grain boundaries of the previous austenite.

A COMPARATIVE STUDY OF LARGE HYDRAULIC GENERATORS WITH AIR-COOLING AND WATER-COOLING

1993 ◽  
Vol 21 (5) ◽  
pp. 605-613
Author(s):  
LIN XIANSHU ◽  
GAO JINLING ◽  
YU GUOQIN
Keyword(s):  
Comparative Study ◽  
Air Cooling ◽  
Water Cooling
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