Computer Simulation of Heat Treatment Process for 125MN Plunger

2008 ◽  
Vol 575-578 ◽  
pp. 1129-1133
Author(s):  
Chun Li Mo ◽  
Jin Ling ◽  
Yi Kun Luan ◽  
Cai Ping Shen
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Real Time ◽  
High Speed ◽  
Treatment Process ◽  
Heat Treatment Process ◽  
Warm Up ◽  
Holding Period

The heavy 125MN Plunger is weight 140 ton, its heat treatment process include two part, one is heat and another is quenching in order to attain certain hardness on its surface and toughness on its body. Differential temperature heat process were made in well resistance furnace, the heat time include warm-up and holding period and high-speed increasing period. The total time is about 30-40 hours.The differential heat treatment process is an essential step in the production of heavy plunger, and it determines the hardness distribution on the sample surface. In this paper, a program to calculate real-time temperature during the heat treatment process was developed based on a great deal of experiments. Using this subroutine program the temperature field of hollow heavy plunger during differential heat treatment process was calculated. The result shows that the simulated temperature was agreed with the real temperature in the warm-up and holding period of the heat treatment process. In the calculation temperature field ,based on the convectional heat transfer coefficient and radiate heat transfer coefficient, the corrected heat transfer coefficient were induced to compose comprehensive heat transfer coefficient. The temperature predicted in warm-up and holding period were correct, the error was below 1%. At the high-speed increasing period, the time when the external temperature reach enacting was predict accurately. So the computer simulation can give real time prediction to decide parameters of the heat treatment process. The result also show that the program developed is sample and applied , it fit for predicting temperature at workshop real time and it is available to deal with complex process .

A Photographic Study of Flow Boiling Stability on a Plain Surface With Tapered Manifold

2015 ◽  
Author(s):  
Ankit Kalani ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Flow Boiling ◽  
High Heat ◽  
Bubble Nucleation ◽  
High Heat Transfer ◽  
Plain Surface ◽  
High Heat Transfer Coefficient

Flow boiling in microchannels offers many advantages such as high heat transfer coefficient, higher surface area to volume ratio, low coolant inventory, uniform temperature control and compact design. The application of these flow boiling systems has been severely limited due to early critical heat flux (CHF) and flow instability. Recently, a number of studies have focused on variable flow cross-sectional area to augment the thermal performance of microchannels. In a previous work, the open microchannel with manifold (OMM) configuration was experimentally investigated to provide high heat transfer coefficient coupled with high CHF and low pressure drop. In the current work, high speed images of plain surface using tapered manifold are obtained to gain an insight into the nucleating bubble behavior. The mechanism of bubble nucleation, growth and departure are described through high speed images. Formation of dry spots for both tapered and uniform manifold geometry is also discussed.

Subcooled Boiling of Surfactant Solutions

2000 ◽  
Author(s):  
G. Hetsroni ◽  
M. Gurevich ◽  
A. Mosyak ◽  
R. Rozenblit ◽  
L. P. Yarin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Heated Surface ◽  
Pure Water ◽  
Video Camera ◽  
Subcooled Boiling ◽  
Bubble Behavior ◽  
Boiling Hysteresis

Abstract During subcooled boiling of pure water and water with cationic surfactants, the motion of bubbles and the temperature of the heated surface were recorded by both a high-speed video camera and an infrared radiometer. The results show that the bubble behavior and the heat transfer mechanism for the surfactant are quite different from those of clear water. Bubbles formed in Habon G solutions were much smaller man those in water and the surface was covered with them faster. Boiling hysteresis is found for degraded solutions. Dependencies of heat transfer coefficient for various solutions were obtained and compared. The boiling curves of surfactant are quite different from the boiling curve of pure water. Experimental results demonstrate that the heat transfer coefficient of the boiling process can be enhanced considerably by the addition of a small amount of Habon G. The experiments show that the limitations of the ER technique with respect to frequency response are outweighed by its unique capacity to measure wall temperature distribution with high spatial resolution over an area encompassing many nucleation sites and over long periods.

Shellside Vacuum Condensation With a Noncondensable Gas

2016 ◽  
Author(s):  
Susan N. Ritchey
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Process Conditions ◽  
Transfer Data ◽  
Noncondensable Gas ◽  
Overall Heat Transfer Coefficient ◽  
Vacuum Condensation

Shell-and-tube vacuum condensers are present in many industrial applications such as chemical manufacturing, distillation, and power production [1–3]. They are often used because operating a condenser under vacuum pressures can increase the efficiency of energy conversion, which increases the overall plant efficiency and saves money. Typical operating pressures in the petrochemical industry span a wide range of values, from one atmosphere (101.3 kPa) down to a medium vacuum (1 kPa). The current shellside condensation methods used to predict heat transfer coefficients are based on data collected near or above atmospheric pressure, and the available literature on shellside vacuum condensation generally lacks experimental data. The accuracy of these methods in vacuum conditions well below atmospheric pressure has yet to be validated. Recently, HTRI designed and constructed the Low Pressure Condensation Unit (LPCU) with a rectangular shellside test condenser. To date, heat transfer data have been collected in the LPCU for shellside condensation of a pure hydrocarbon and of a hydrocarbon with noncondensable gas at vacuum pressures ranging from 2.8 to 45 kPa (21 to 338 Torr). Traditional condensation literature methods underpredict the overall heat transfer coefficient by 20.8% ± 20.4% for the pure condensing fluid; whereas they overpredict heat transfer by 36.8% ± 40.0% with the addition of the noncondensable gas. Over or under predicting the overall heat transfer coefficient in the presence of noncondensable gases leads to inefficient condenser designs and the inability to achieve desired process conditions. With the addition of the noncondensable gas, the measured heat exchanger duty was significantly reduced compared to the pure fluid, even at inlet mole fractions below 5%. In one case, a noncondensable inlet mole fraction of 0.63% was estimated to reduce the duty by approximately 10%. Analysis of the acquired high-speed videos shows that the film thickness changes significantly from the top row to the bottom. The videos also display condensate drainage patterns and droplet interactions. The ripples and splashing of the condensate observed in the videos indicates that the Nusselt idealized model is not appropriate for analysis of a real condenser. This article presents the collected heat transfer data and high-speed images of shellside vacuum condensation flow patterns.

Thermal Response Characteristics of Flat Plate Heated by High Temperature and High Speed Flow

2013 ◽  
Vol 448-453 ◽  
pp. 3316-3319
Author(s):  
Chuang Sun ◽  
Yang Zhao ◽  
De Fu Li ◽  
Qing Ai ◽  
Xin Lin Xia
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
High Speed ◽  
Convection Heat Transfer ◽  
Thermal Response ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient

According to the view of heat transfer, the process of the fluid flow with high temperature and high speed over a flat plate may be considered as the heat transfer process within a compressible thermal boundary layer. Based on the numerical results of thermal isolation assumption, combining the temperature comparison with modification method, a coupled method of convection heat transfer coefficient with temperature field of the plate is established, and the characteristics of the thermal response for the flat plate is dominated. Take some ribbed plates as instances, the convection heat transfer coefficient and temperature field of the plate are simulated through the provided coupled method. The results show that, not only the position and materials of the plate influence the convection heat transfer coefficient, but also the time.

Thermal Investigation of Integrated Combustor Vane Concept Under Engine-Realistic Conditions

2016 ◽  
Author(s):  
Simon Jacobi ◽  
Budimir Rosic
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbines ◽  
High Speed ◽  
Secondary Flows ◽  
Experimental Measurements ◽  
Thermal Investigation ◽  
Nozzle Guide ◽  
The Heat Transfer Coefficient

This paper presents a thermal investigation of the Integrated Combustor Vane concept for power generation gas turbines with individual can combustors. This concept has the potential to replace the high-pressure turbine’s first vanes by prolonged combustor walls. Experimental measurements are performed on a linear high-speed cascade consisting of two can combustors and two integrated vanes. The modularity of the facility allows for the testing at engine-realistic high turbulence levels, as well as swirl strengths with opposing swirl directions. The heat transfer characteristics of the integrated vanes are compared to conventional nozzle guide vanes. The experimental measurements are supported by detailed numerical simulations using the inhouse CFD code TBLOCK. Experimental as well as numerical results congruently indicate a considerable reduction of the heat transfer coefficient (HTC) on the integrated vanes surfaces and endwalls caused by a differing state of boundary layer thickness. The studies furthermore depict a slight, non-detrimental shift in the heat transfer coefficient distributions and the strength of the integrated vanes secondary flows as a result of engine-realistic combustor swirl.

The Deformation Rule of the Cooled U75V Heavy Rail Caused by the Different Heat Transfer Coefficient

2011 ◽  
Vol 299-300 ◽  
pp. 1005-1011 ◽  
Author(s):  
Ming Xin Gao ◽  
Pei Long Wang ◽  
Hao Jia ◽  
Shan Hu Tong ◽  
Hua Song ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Reference Value ◽  
Ansys Software ◽  
Cooling Process ◽  
Technological Parameters ◽  
The Heat Transfer Coefficient ◽  
Heavy Rail

When rolled heavy rail is on the cooling bed for natural cooling, the heat transfer coefficient has important effect on the bending and section sizes of cooled heavy rail. In the paper, the heat-stress couple module ofANSYS software is adopted to carry on numerical simulation on the cooling process of 60kg/m U75V heavy rail, and we obtain the change rule that heat transfer coefficient has effect on bending curvature and section sizes of cooled heavy rail. This study is of great reference value on cooling bed design and the formulation of cooling technological parameters for high speed heavy rail.

scholarly journals THE STUDY OF TEMPERATURES IN A TUNGSTEN ELECTRODE AT REVERSE POLARITY ARCING

2021 ◽  
pp. 69-79
Author(s):  
V. P. Sidorov ◽  
◽  
D. E. Sovetkin ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
B Value ◽  
Limiting Current ◽  
Reverse Polarity ◽  
Start Time ◽  
Tungsten Electrode ◽  
Good Coincidence

The paper considers the features of energy release in a tungsten electrode under the reverse polarity TIG welding. The study substantiates the statement that the chemical composition of an electrode does not significantly affect the transfer of anode power to it. The specific effective power of an electrode is substantiated and taken as 6 W/A. The authors analyzed the features of arcing on the flat tip of a 3 mm diameter electrode using high-speed video. The analysis identified that at limiting currents ensuring tip melting, the tip heating is uniform over the cross-section. As a design scheme, the authors selected a continuous flat heat source on the semi-infinite rod surface with surface heat transfer. The authors obtained averaged values for volumetric heat capacity сρ=3.2 J/(cm3∙°С) and heat transfer coefficient а=0.3 cm2/s. The current at which the tip melting temperature is reached was taken as a limiting current. Using the limiting current value and start time of the electrode tip melting, the authors calculated the electrode heat transfer coefficient value b. The calculated melting depth for the over-limiting current welding mode showed good coincidence with an experiment. The authors recalculated the b value for the electrodes of 4-, 5-, and 6-mm diameter and calculated limiting currents for these diameters. The design limiting currents for these diameters also showed good coincidence with experimental results. The study showed that the increase of a coefficient up to 0.4 cm2/s does not cause changes in temperature and limiting currents at simultaneous сρ adjustment according to the constant thermal and physical properties сρа0.5. As a result, the authors obtained temperature dependencies for the electrode over time and length. Time dependence of the electrode tip heating allows calculating limiting currents with the decrease in arcing time.

Numerical Investigations on the Heat Transfer Performance of Transonic Squealer Tip With Different Film Cooling Layouts

2020 ◽  
Author(s):  
Shijie Jiang ◽  
Zhigang Li ◽  
Jun Li ◽  
Liming Song
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Rate ◽  
Film Cooling ◽  
High Speed ◽  
Thermal Stresses ◽  
High Heat ◽  
Tip Leakage Flow ◽  
High Heat Transfer

Abstract Tip leakage flow in high speed turbine induce significant thermal loads and give rise to intense thermal stresses on blade tip, while increasing inlet pressure tends to accelerate leakage velocity beyond transonic regime. The present research quantifies heat transfer and film cooling effect on a squealer tip with three film cooling layouts, three coolant mass flow rates and a relative casing movement. The results indicate that area-averaged HTC of PS layout is higher than that of CAM layout by 6.9% and that of SS layout by 5.7% when coolant flow rate equals to 0.6% mainstream flow rate. By comparison, it is clearly observed that area of the high heat transfer coefficient regions are significantly enlarged when the flow rate of coolant is increased. With relative casing movement, a significant high HTC stripe parallel to pressure side rim is formed. In case of the PS layout, heat transfer coefficient is reduced by 7.3% with casing movement. While in case of CAM layout and SS layout, heat transfer coefficient increased by 4.8% and 2.3% with casing movement, respectively. Detailed flow patterns with three film cooling layouts are also illustrated.

PENGARUH HARDENING PADA BAJA JIS G 4051 GRADE S45C TERHADAP SIFAT MEKANIS DAN STRUKTUR MIKRO

2012 ◽  
Vol 11 (2) ◽  
Author(s):  
Koos Sarjono
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Treatment Process ◽  
Engineering Industry ◽  
Heat Treatment Process ◽  
High Quality ◽  
Metallic Material ◽  
Warm Up ◽  
Industrial Demand

Steel represents a metallic material which is still dominantly used in the engineering industry and mechanical construction. In order to fulfil the industrial demand, the high quality and mechanical properties of steel has to be always available.It is necessary to conduct a heat-treatment process to identify the improvement of mechanical properties and microstructure of steel JIS G 4051 grade S 45 C .Results of the heat-treatment process indicate that the maximum tensile strength of the investigated steel is 1074 MPa , it is earning from the warm-up temperature 860 °C and the highest hardness of the investigated steel is 579 HV it is earning from the warm-up temperature 920 °C . These results meet to AISI – SAE 1045 or JIS G 4051 grade S 45 C standard.

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