HEAT TRANSFER DURING TRANSIENT FLOW TO WATER AT VARIOUS PRESSURES

1986 ◽  
Author(s):  
J. E. Byrne ◽  
H.L. Ding ◽  
H.S. Ergur ◽  
Hamid R. Falaki
Keyword(s):  
Heat Transfer ◽  
Transient Flow

Mathematical Modeling of Transient Flow and Heat Transfer in Gas Stirred Molten Steel

2001 ◽  
Author(s):  
J. L. Xia ◽  
T. Ahokainen
Keyword(s):  
Heat Transfer ◽  
Molten Steel ◽  
Thermal Stratification ◽  
Transient Flow ◽  
Liquid Interface ◽  
Turbulent Dispersion ◽  
Steel Ladle ◽  
Bubble Liquid ◽  
Flow And Heat Transfer ◽  
Heat Transfer Correlations

Abstract Transient two phase flow and heat transfer in a gas-stirred steel ladle are numerically investigated. An Eulerian two fluid approach is used. The drag, lift and turbulent dispersion forces are taken into account for the interface interactions. Different interface heat transfer correlations such as Ranz-Marshall and Hughmark relations are used to examine the influence of heat transfer between gas-liquid interface on the flow. The flow pattern, the histories of both gas and molten steel temperatures, and the thermal stratification history are presented. Results show that gas injection can homogenize thermal field and result in a thermal stratification of about 2 °C only (not complete homogenization). The different heat transfer correlations examined for the bubble-liquid interface have negligible impact on the flow and thermal fields. Predictions are compared with experimental data measured in an industrial ladle and a reasonable agreement is achieved.

scholarly journals Numerical study on the thermohydraulic performance of a reciprocating room temperature active magnetic regenerator

2019 ◽  
Vol 128 ◽  
pp. 07001
Author(s):  
Georges El Achkar ◽  
Bin Liu ◽  
Rachid Bennacer
Keyword(s):  
Heat Transfer ◽  
Room Temperature ◽  
Transient Flow ◽  
Numerical Study ◽  
Working Fluid ◽  
Comsol Multiphysics ◽  
Transfer Model ◽  
Two Dimensional ◽  
Active Magnetic Regenerator ◽  
Magnetic Regenerator

In this paper, the thermohydraulic performance of a reciprocating room temperature active magnetic regenerator (AMR), with gadolinium (Gd) particles used as a magnetocaloric material (MCM) and water used as a working fluid, was numerically investigated. A two-dimensional transient flow model was developed using COMSOL Multiphysics, in order to determine the water flow distribution in two AMRs of cross and parallel Gd particles distributions for different water inlet velocities of 0.06 m.s-1, 0.08 m.s-1 , 0.1 m.s-1 and 0.12 m.s-1. The Gd particles have a radius of 1.5 mm and a distance from one another of 0.9 mm. Based on the simulations results of the first model, a two-dimensional transient coupled flow and heat transfer model was then developed using COMSOL Multiphysics, in order to characterise the convective heat transfer in the AMR of cross Gd particles distribution for the same water inlet velocities.

scholarly journals Development of A Process for Predicting the Overall Heat Transfer Coefficient for Transient Heat Transfer in An Exhaust System using CFD

2019 ◽  
Vol 8 (2) ◽  
pp. 2529-2533
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Analytical Solution ◽  
Transfer Coefficient ◽  
Gas Flow ◽  
Transient Flow ◽  
Exhaust System ◽  
Outlet Temperature ◽  
Governing Equations ◽  
Overall Heat Transfer Coefficient

The analysis of heat transfer of automotive exhaust system is most important since their prominence in the design and also in the optimization phase of exhaust after treatment system.This paperdeals with the process which can be useful to predict the overall heat transfer coefficient for the transient flow of pipe in the after treatment system. This considers the convection of heat along gas flow, the convection between gas and wall, conduction through wall, radiation and of course convection to the ambient. Governing equations are obtained for the transient flow in a pipe for calculating gas temperature and wall temperature at distance x and time t. Analytical solution will be computed using CFD techniques for these governing equations. From the obtained analytical solution to the transient flow in pipe an excel tool will be developed which can be able to give the outlet temperature of the pipe in transient flow at length x and time t, total heat loss from pipe to the ambient, overall heat transfer coefficient for the pipe

scholarly journals Numerical Simulation for Preheating New Submarine Hot Oil Pipelines

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3518
Author(s):  
Yong Wang ◽  
Nan Wei ◽  
Dejun Wan ◽  
Shouxi Wang ◽  
Zongming Yuan
Keyword(s):  
Heat Transfer ◽  
Transient Flow ◽  
Maximum Flow ◽  
Percentage Error ◽  
Fluid Temperature ◽  
Transfer Coefficients ◽  
Coupled Heat Transfer ◽  
Comparison Results ◽  
Oil Pipelines ◽  
Lower Fluid

For new submarine hot oil pipelines, accurate simulation of preheating is difficult owing to complex transient flow and coupled heat transfer happening. Using quasi-steady equations to simulate preheating is inadequate as the hydraulic transient phenomenon is neglected. Considering this fact, this paper constructs an unsteady flow and heat transfer coupled mathematical model for the preheating process. By combining the double method of characteristics (DMOC) and finite element method (FEM), a numerical methodology is proposed, namely, DMOC-FEM. Its accuracy is validated by field data collected from the Bohai sea, China, showing the mean absolute percentage error (MAPE) of 4.27%. Simulation results demonstrate that the preheating medium mainly warms submarine pipe walls rather than the surrounding subsea mud. Furthermore, during the preheating process, the equivalent overall heat transfer coefficients deduced performs more applicably than the inverse-calculation method in presenting the unsteady propagation of fluid temperature with time and distance. Finally, according to the comparison results of 11 preheating plans, subject to a rated heat power and maximum flow, the preheating parameter at a lower fluid temperature combined with a higher flow rate will produce a better preheating effect.

Transient Numerical Model on the Design Optimization of the Adiabatic Section Length for the Pulsating Heat Pipe

2021 ◽  
Vol 11 (20) ◽  
pp. 9432
Author(s):  
Kangli Bao ◽  
Yuan Zhuang ◽  
Xu Gao ◽  
Yuanyuan Xu ◽  
Xilei Wu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Thermal Resistance ◽  
Heat Input ◽  
Transient Flow ◽  
High Heat ◽  
Pulsating Heat Pipe ◽  
Mean Velocity ◽  
High Heat Input ◽  
Adiabatic Section

In the application of pulsating heat pipes (PHPs), the lengths of the adiabatic sections are usually determined by the distance between the heat source and the heat sink, and have important effects on the performance of PHPs. However, there was little research on the effect of the adiabatic section lengths on the performance of PHPs. In this work, a new transient numerical model was proposed to investigate the transient flow and the heat transfer for PHPs with various adiabatic section lengths of 60, 120, 180, and 240 mm. Based on the numerical results, the flow and the heat transfer characteristics of the PHPs were analyzed. It was found that the flow velocities in the PHP with different adiabatic lengths increased with the increase in the heat input, and the mean velocity was calculated to be in the range of 0.139–0.428 m/s, which was consistent with the previous experimental results. The start-up performance of the PHP was better with shorter adiabatic section length. Furthermore, the thermal resistances of the PHPs with different adiabatic section lengths were calculated to analyze the effects of the adiabatic section length on the performance of the PHP. The results showed that when the heat input was 20 W, the PHP with the adiabatic section of 60 mm showed the lowest thermal resistance, whereas the PHP with longer adiabatic section length presented lower thermal resistance at high heat input (≥25 W).

Transient Flow Boiling Heat Transfer in Water

2021 ◽  
Vol 56 (5) ◽  
pp. 810-815
Author(s):  
Makoto Shibahara ◽  
Qiusheng Liu ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Transient Flow ◽  
Flow Boiling ◽  
Flow Boiling Heat Transfer

Transient flow pattern based microscale boiling heat transfer mechanisms

2005 ◽  
Vol 15 (6) ◽  
pp. 1344-1361 ◽  
Author(s):  
Jinliang Xu ◽  
Sheng Shen ◽  
Yunhua Gan ◽  
Yuxiu Li ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Boiling Heat Transfer ◽  
Transient Flow ◽  
Transfer Mechanisms
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