scholarly journals Numerical Simulation of Solidification Structure of Al Alloy During Centrifugal Casting

2021 ◽  
Vol 2125 (1) ◽  
pp. 012043
Author(s):  
Xiaoming Qian ◽  
Xue Sheng ◽  
Longzhou Meng ◽  
Yong Li ◽  
Zhaodong Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Rotation Speed ◽  
Centrifugal Casting ◽  
Solidification Structure ◽  
Grain Structure ◽  
Process Conditions ◽  
Al Alloy ◽  
Columnar Crystal

Abstract The centrifugal casting process of 6082 Al alloy was simulated by ProCAST software. The effects of rotation speed and heat transfer coefficient on the filling and solidification behaviour were analysed. The porosity of the cast pipe increases with the increase of the rotation speed and decreases with the increase of heat transfer coefficient. The CAFE model was used to simulate the grain structure of centrifugal cast Al alloy under different process conditions. When the rotation speed and heat transfer coefficient increase, the length of columnar crystal region will increase and the grain will be refined.

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.

scholarly journals Heat Transfer Coefficient at Cast-Mold Interface During Centrifugal Casting: Calculation of Air Gap

2018 ◽  
Vol 49 (3) ◽  
pp. 1421-1433 ◽  
Author(s):  
Jan Bohacek ◽  
Abdellah Kharicha ◽  
Andreas Ludwig ◽  
Menghuai Wu ◽  
Ebrahim Karimi-Sibaki
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Centrifugal Casting ◽  
Air Gap

The Surface Heat Transfer Coefficient Model of 7075 Al-Alloy Extrusion Product and its Temperature Prediction

2013 ◽  
Vol 749 ◽  
pp. 229-236
Author(s):  
Wen Rong Hou ◽  
Wei Bing Ji ◽  
Zhi Hao Zhang ◽  
Jian Xin Xie
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Surface Heat ◽  
Al Alloy ◽  
Surface Heat Transfer ◽  
7075 Al Alloy ◽  
Surface Heat Transfer Coefficient ◽  
Extrusion Product ◽  
The Relationship

Surface heat transfer coefficient is a key parameter for accurately predicting the extrusion product temperature near the die exit and then achieving isothermal extrusion by speed controlling. Based on the heat transfer characteristics of extrusion product during cooling process, a dynamic loading method of heat transfer boundary conditions was proposed. The surface heat transfer coefficient model of 7075 Al-alloy extrusion product was established using the dynamic loading method and inverse calculation comprehensively. The model indicated the relationship among surface heat transfer coefficient h, surface temperature T and initial temperature T0 as h=1.16T-0.97T0. Its accuracy is high enough for calculating the surface temperature of 7075 Al-alloy extrusion product. According to the model and the experimental data, the relationship between the product and the measured temperatures can be established. It provides an effective way to solve the problem that the extrusion product temperature near the die exit cannot be directly measured.

scholarly journals Method for residual strain modeling taking into account mold and distribution of heat transfer coefficients for thermoset composite material parts

2021 ◽  
Author(s):  
Mikhail Kiauka ◽  
Mikhail Kasatkin ◽  
Iuliia Tcygantceva ◽  
Nikolai Efimov-Soini ◽  
Alexey Borovkov
Keyword(s):  
Heat Transfer ◽  
Composite Material ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Residual Strain ◽  
Composite Panel ◽  
Process Conditions ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Strain Modeling

AbstractThe article presents a technique for process-induced residual strain modeling for thermoset composite material parts. The model takes into account the mechanical and thermal contact between the part and the mold. The technique is implemented in the ABAQUS software using user subroutines. Using the technique, it is possible to clarify the distribution of the heat transfer coefficient on the surface of the part and mold using the CFD method. Distribution of heat transfer coefficients are obtained in ANSYS CFX under the appropriate process conditions. The method is verified for the U-shaped sample. Also, the results of modeling the stringer-stiffened curved composite panel using the developed technique without taking into account the mold and heat transfer coefficient distribution are presented.

Simulation of Mg-Gd Alloy during Solidification Process

2016 ◽  
Vol 873 ◽  
pp. 28-32
Author(s):  
Shu Mei Liu ◽  
Li Ping Zhao ◽  
Zhao Li ◽  
Jian Chao Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Formation Control ◽  
Crystallization Process ◽  
Solidification Process ◽  
Solidification Structure ◽  
Control Parameters ◽  
Average Grain Size ◽  
The Heat Transfer Coefficient

This paper uses ProCast software to simulate Mg-Gd alloy solidification process, calculates temperature field and solidification field for Mg-9.76Gd at different stages and compares the influence of different heat transfer coefficient on the solidification structure. The results show that the crystallization process which is simulated is consistent with the actual crystallization process; as the heat transfer coefficient increases, the average grain size decreases. With the result, the reasonable casting formation control parameters can guide the practical production, which can reduce human and financial resources.

Note. Overall Heat Transfer Coefficient to Canned Liquid During End-over-end Sterilisation

2006 ◽  
Vol 12 (6) ◽  
pp. 515-520 ◽  
Author(s):  
R. L. Garrote ◽  
E. R. Silva ◽  
R. D. Roa ◽  
R. A. Bertone
Keyword(s):  
Heat Transfer ◽  
Aqueous Solution ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Rotation Speed ◽  
Characteristic Dimension ◽  
Overall Heat Transfer Coefficient ◽  
Prandtl Numbers

The overall heat transfer coefficient as a function of rotation speed (5–20rpm) was calculated for cans containing a 2% NaCl and 1.5% sucrose aqueous solution during end-over-end heat sterilisation at 120°C. The values obtained for the overall heat transfer coefficient, U (W/m2 °C), were: 544.4±85.3 at 5rpm, 710.7±24.5 at 10rpm, 760.5±17.7 at 15rpm and 941.6±22.1 at 20rpm. A correlation was developed in terms of Nusselt, rotational Reynolds and Prandtl numbers to predict U(Nu = 1.866Re0.379 Pr0.38). The characteristic dimension in Nu and Re was the diameter of the can. This correlation (R2 = 0.88) was valid for Re within the range of 3,012–14,820 and Pr within 2.02–2.63 values.

scholarly journals Influence of the outlet air temperature on the thermohydraulic behaviour of air coolers

2003 ◽  
Vol 57 (4) ◽  
pp. 159-164
Author(s):  
Emila Djordjevic ◽  
Slobodan Serbanovic ◽  
Dejan Milosevic ◽  
Aleksandar Tasic ◽  
Bojan Djordjevic
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Air Temperature ◽  
Process Conditions ◽  
Side Pressure ◽  
Vapour Mixture ◽  
Process Fluid ◽  
The One

The determination of the optimal process conditions for the operation of air coolers demands a detailed analysis of their thermohydraulic behaviour on the one hand, and the estimation of the operating costs, on the other. One of the main parameters of the thermohydraulic behaviour of this type of equipment, is the outlet air temperature. The influence of the outlet air temperature on the performance of air coolers (heat transfer coefficient overall heat transfer coefficient, required surface area for heat transfer air-side pressure drop, fan power consumption and sound pressure level) was investigated in this study. All the computations, using AirCooler software [1], were applied to cooling of the process fluid and the condensation of a multicomponent vapour mixture on two industrial devices of known geometries.

scholarly journals Non-Isothermal Hydrodynamic Characteristics of a Nanofluid in a Fin-Attached Rotating Tube Bundle

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1153
Author(s):  
Mashhour A. Alazwari ◽  
Mohammad Reza Safaei
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Rotation Speed ◽  
Tube Bundle ◽  
Heat Transfer Fluid ◽  
Hydrodynamic Characteristics ◽  
The Heat Transfer Coefficient

In the present study, a novel configuration of a rotating tube bundle was simulated under non-isothermal hydrodynamic conditions using a mixture model. Eight fins were considered in this study, which targeted the hydrodynamics of the system. An aqueous copper nanofluid was used as the heat transfer fluid. Various operating factors, such as rotation speed (up to 500 rad/s), Reynolds number (10–80), and concentration of the nanofluid (0.0–4.0%) were applied, and the performance of the microchannel heat exchanger was assessed. It was found that the heat transfer coefficient of the system could be enhanced by increasing the Reynolds number, the concentration of the nanofluid, and the rotation speed. The maximum enhancement in the heat transfer coefficient (HTC) was 258% after adding a 4% volumetric nanoparticle concentration to the base fluid and increasing Re from 10 to 80 and ω from 0 to 500 rad/s. Furthermore, at Re = 80 and ω = 500 rad/s, the HTC values measured for the nanofluid were 42.3% higher than those calculated for water, showing the nanoparticles' positive impact on the heat transfer paradigm. Moreover, it was identified that copper nanoparticles' presence had no significant effect on the system's pressure drop. This was attributed to the interaction of the fluid flow and circulated flow around the tubes. Finally, the heat transfer coefficient and pressure drop had no considerable changes when augmenting the rotation speed at high Reynolds numbers.

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