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

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.

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Residual Stress Analysis Considering Phase Transformation and Transformation Plasticity for Heat-Treated Large Size Shaft

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.725.647 ◽

2016 ◽

Vol 725 ◽

pp. 647-652 ◽

Cited By ~ 2

Author(s):

Yusuke Yanagisawa ◽

Yasuhiro Kishi ◽

Katsuhiko Sasaki

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

Phase Transformation ◽

Air Cooling ◽

Water Cooling ◽

Stress Distributions ◽

Transformation Plasticity ◽

Large Size ◽

Heat Treated ◽

Good Agreement

The residual stress distributions of the forgings after both water-cooling and air-cooling were measured experimentally. The residual stress occurring during the heat-treatment was also simulated considering the phase transformation and the transformation plasticity. A comparison of the experiments with the simulations showed a good agreement. These results shows that the transformation plastic strain plays an important role in the heat treatment of large forged shafts.

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New Results of the Heat-Treated CuZn39Pb3 Brass Behavior and Resistance to Cavitation Erosion

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.890.173 ◽

2021 ◽

Vol 890 ◽

pp. 173-180

Author(s):

Ilare Bordeaşu ◽

Nicușor Alin Sîrbu ◽

Iosif Lazăr ◽

Ion Mitelea ◽

Cristian Ghera ◽

...

Keyword(s):

Heat Treatment ◽

Cavitation Erosion ◽

Stress Relief ◽

Air Cooling ◽

Water Cooling ◽

Characteristic Parameters ◽

Volume Heat ◽

Heat Treated ◽

Hardness Increase

The paper presents the results of the behavior and resistance to the erosion by vibrating cavitation of the CuZn39Pb3 brass, obtained by quenching the volume heat treatment from 800°C with water cooling, followed by the stress-relief to 250°C, with air cooling. Comparison with both the delivery status and the naval brass (used for ship propellers), based on the characteristic parameters values, recommended by the ASTM G32 standards and used in the Cavitation Laboratory of the Polytechnic University of Timisoara, shows that the hardness increase resulted from the heat treatment led to a significant increase of resistance to vibrating cavitation.

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Corrosion Resistance of Industrial Pure Titanium and its Alloys under High Temperature and Different Cooling Methods

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.891.3 ◽

2021 ◽

Vol 891 ◽

pp. 3-9

Author(s):

Cang Tian Wang ◽

Qing Long Meng ◽

Fang Hao Chen ◽

Jing Hong Wang ◽

You Ran Zhi ◽

...

Keyword(s):

Corrosion Resistance ◽

Acid Corrosion ◽

Pure Titanium ◽

Corrosion Current ◽

Chemical Equipment ◽

Air Cooling ◽

Water Cooling ◽

Corrosion Condition ◽

Impedance Technique ◽

Cooling Methods

Industrial pure titanium (TA2) and Ti-6Al-4V (TC4) have been widely available for chemical equipment. However, the corrosion resistance changes during their post-fire performance. In this research, the electrochemical properties of industrial pure titanium and Ti-6Al-4V after heat treatment and different cooling methods were analyzed by AC impedance technique and dynamic polarization method. The results support two conclusions. Firstly, when the temperature is approximate to the phase transition point, for pure titanium and its alloys, water-cooling can obtain better corrosion resistance than air-cooling. With regard to pure titanium, its best corrosion resistance can be obtained at 800°C under water-cooling. For Ti-6Al-4V, its best corrosion resistance can be obtained when the temperature reached 910 °C under water cooling condition. Secondly, the corrosion current density under acid corrosion condition has risen compared with neutral corrosion condition. These results can provide some experimental data and theoretical basis for post-fire anticorrosion performance of titanium materials, and also support the safety, risk evaluation of titanium equipment.

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Study on Metallography Test of the Steel SPV490 for Atmospheric Storage Tank After Fire

Volume 1B: Codes and Standards ◽

10.1115/pvp2016-63058 ◽

2016 ◽

Author(s):

Zhou Fang ◽

Weiwei Hu ◽

Deyu Liu ◽

Guanghai Li ◽

Zhe Wang

Keyword(s):

Mechanical Properties ◽

Working Conditions ◽

Storage Tank ◽

High Strength ◽

Air Cooling ◽

Microscopic Structure ◽

Water Cooling ◽

Storage Tanks ◽

Fire Temperature ◽

Optical Microstructure

The fire process was simulated by the heat treatment to the Steel SPV490 of atmospheric storage tank, thereby obtaining the metal specimens in different fire temperature, holding time, and cooling modes. And as the temperature increases, the microscopic structure of Steel SPV490 changes under different working conditions, which could be shown in optical microstructure pictures after doing the interception, inlay, polishing, finishing to the specimens. The result shows that, the mechanical properties of the Steel SPV490 for storage tank changes as the temperature rising from the microscopic view. Nodulizing of the cementite in pearlite occurs, and the strength decreases when the high strength steel SPV490 of large atmospheric storage tanks under air cooling condition below 700 °C, however, it equivalents to the normalizing process, as the sorbite occurs in the steel, and the strength increases a bit when the temperature is above 900 °C. The water-cooling of steel SPV490 above 900 °C equivalents to the process of quenching. The occurrence of martensitic substantially increases the strength and the brittleness, and the elongation decreases rapidly.

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Study of CO2injection on the desulfurization of low-titanium slag

Metallurgical Research & Technology ◽

10.1051/metal/2018120 ◽

2019 ◽

Vol 116 (4) ◽

pp. 417

Author(s):

Baohua Wang ◽

Mingbo Zhang ◽

Rong Zhu ◽

Shengtao Qiu

Keyword(s):

Air Cooling ◽

Water Cooling ◽

Steelmaking Process ◽

Titanium Slag ◽

Desulfurization Rate ◽

Sulfate Ions ◽

Injection Process ◽

Desulfurization Process ◽

Low Sulfur ◽

Cooling Air

A new idea that the low-titanium slag (LTS) used in the steelmaking process after CO2injection desulfurization is proposed in this paper. The CO2injection process mainly involves the grinding of low-titanium slag, mixing of slag and water, CO2injection, filtration, and then obtains the low sulfur and low titanium slag. The effects of cooling rates (water cooling, air cooling, crucible cooling, and furnace cooling) and CO2injection on the desulfurization of LTS were studied by both experimental and thermodynamic calculations. The results showed that sulfite and sulfate ions couldn’t be removed from LTS using this method, and the main removal substance in slag was sulfide ion S2−. The desulfurization mechanism with CO2injection was that the CO2injection reacted with H2O to form H2CO3, and then the H+disrupted from H2CO3reacted with the S2−in the slag to achieve desulfurization. During the desulfurization process, the desulfurization reaction was mainly determined by S2− + CO2(aq) + H2O (l) = CO32− + H2S(g) within the first 5 min, and then the main desulfurization reaction was S2− + 2CO2(aq) + 2H2O(l) = 2HCO3− + H2S(g). As the cooling rate decreasing, the desulfurization rate of LTS increased. The desulfurization effect of furnace-cooled slag is the highest in four kinds of slag. The desulfurization rate of furnace-cooled slag reaches 72.28%, which is 4.34, 1.75 and 1.15 times than that of water-cooled slag, air-cooled slag and crucible-cooled slag, respectively. The optimal rate of desulfurization is 80.0%.

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Comparison and evaluation of air cooling and water cooling in resource consumption and economic performance

Energy ◽

10.1016/j.energy.2018.04.095 ◽

2018 ◽

Vol 154 ◽

pp. 157-167 ◽

Cited By ~ 7

Author(s):

Haitian Zhang ◽

Xiao Feng ◽

Yufei Wang

Keyword(s):

Economic Performance ◽

Resource Consumption ◽

Air Cooling ◽

Water Cooling

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Design and implementation of a directly cooled PV/T

Journal of Engineering Design and Technology ◽

10.1108/jedt-09-2013-0063 ◽

2015 ◽

Vol 13 (3) ◽

pp. 369-379

Author(s):

Busiso Mtunzi ◽

Edson L. Meyer

Keyword(s):

Hybrid System ◽

Design Methodology ◽

Air Cooling ◽

Water Cooling ◽

Content Type ◽

Water Ingress ◽

Design And Implementation ◽

Pv Module ◽

Pv Modules ◽

Practical Implications

Purpose – The purpose of this paper is to design and implement a directly cooled photovoltaic thermal (PV/T) hybrid system. Design/methodology/approach – The research design subjects, instruments and methods that were used to collect data are as detailed in the paper. Two polycrystalline photovoltaic (PV) modules were used in this study. Findings – The directly water-cooled PV module (PV/T) was found to operate better as compared to a naturally cooled module for the first three months. The PV/T initially operated at a higher electrical efficiency for 87 per cent of the day. The monthly energy-saving efficiency of the PV/T was found to be approximately 61 per cent, while the solar utilisation of the naturally cooled PV module M1 was found to be 8.79 per cent and that of M2 was 47.93 per cent. Research limitations/implications – The major limitation was the continued drop in efficiency after the first three months of the PV/T placed outdoors. The fall in the efficiency was attributed to water ingress. Practical implications – Direct water cooling of PV modules is possible, only that a better sealing is needed to prevent water ingress. Originality/value – PV air cooling has been researched on. Use of water as a cooling medium has been carried out using serpentine pipes or riser tube, and no direct water cooling on the back of the module has been researched on.

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