Heat Transfer Analysis of the Micron-Scale Agglomerates of TiO2 Precursor during the Detonation Process

2011 ◽  
Vol 306-307 ◽  
pp. 1138-1141
Author(s):  
Yan Dong Qu ◽  
Xiao Jie Li ◽  
Hong Hao Yan
Keyword(s):  
Heat Transfer ◽  
Mathematic Model ◽  
Heat Transfer Analysis ◽  
Temperature History ◽  
Detonation Products ◽  
Synthesis Mechanism ◽  
Temperature Distributions ◽  
Calculation Results ◽  
Detonation Method ◽  
Detonation Process

Removing water excessively could result in the formation of sphere-like agglomerates of TiO2 precursor with 1-2 μm in size, which was used to prepare TiO2 nanoparticles by detonation method. Different temperature distributions of TiO2 precursor agglomerates influenced the components of detonation products. In order to obtain the temperature distributions, a mathematic model was introduced to study the heat transfer behaviors of the TiO2 precursor agglomerates during the detonation process. The temperature history at spherical center with different spherical radiuses and time was also studied. The calculation results were in good agreement with the experimental results. The heat transfer analysis laid the foundation for the synthesis mechanism research of TiO2 nanoparticles, and it was also helpful to design and optimize experimental procedure.

scholarly journals Numerical study of heat transfer in rectangular channels with single pin fin and pin fin-dimple

2019 ◽  
Vol 124 ◽  
pp. 01010
Author(s):  
A. N. Rogalev ◽  
N. D. Rogalev ◽  
V. O. Kindra ◽  
S. K. Osipov ◽  
A. S. Zonov
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Heat Transfer Analysis ◽  
Navier Stokes ◽  
Pin Fin ◽  
Rectangular Channels ◽  
Calculation Results

Evaluation of the heat transfer and hydraulic performance of a new pin fin-dimple cooling system in a rectangular channel shows its advantage. The performance are compared with the pin fin system ones with 3-D Reynolds averaged Navier-Stokes (RANS) equations. The fluid flow and heat transfer analysis for the Reynolds numbers from 8000 to 70000 involved the shear stress transport turbulence model. The new system forms a high-intensity vortex around the pin fin-dimple that increases the near-wall turbulent mixing level that intensifies the heat transfer. The calculation results indicate increases of the averaged Nusselt number and the averaged friction factor of 7–13% and 7–12% respectively against the pin fin.

CFD Analysis of Thermally Stratified Flow and Conjugate Heat Transfer in a PWR Pressurizer Surgeline

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Jong Chull Jo ◽  
Dong Gu Kang
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Thermal Stresses ◽  
Complex Geometry ◽  
Heat Removal ◽  
Heat Transfer Analysis ◽  
Transient Temperature ◽  
Piping System ◽  
Pressurized Water ◽  
Temperature Distributions

Temperature gradients in the thermally stratified fluid flowing through a pipe may cause undesirable excessive thermal stresses at the pipe wall in the axial, circumferential, and radial directions, which can eventually lead to damages such as deformation, support failure, thermal fatigue, cracking, etc., to the piping systems. Several nuclear power plants have so far experienced such unwelcome mechanical damages to the pressurizer surgeline, feedwater nozzle, high pressure safety injection lines, or residual heat removal lines at a pressurized water reactor (PWR). In this regard, determining with accuracy the transient temperature distributions in the wall of a piping system subjected to internally thermal stratification is the essential prerequisite for the assessment of the structural integrity of such a piping system. In this study, to realistically predict the transient temperature distributions in the wall of an actual PWR pressurizer surgeline with a complex geometry of three-dimensionally bent piping, three-dimensional transient computational fluid dynamics (CFD) calculations involving the conjugate heat transfer analysis are performed for the PWR pressurizer surgeline subjected to either out- or in-surge flows using a commercial CFD code. In addition, the wall temperature distributions obtained by taking into account the existence of wall thickness are compared with those by neglecting it to identify some requirements for a realistic and conservative thermal analysis from a safety viewpoint.

scholarly journals Assessment on Time-Varying Thermal Loading of Engineering Structures Based on a New Solar Radiation Model

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Bo Chen ◽  
Yu-zhou Sun ◽  
Gan-jun Wang ◽  
Ling-yan Duan
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Thermal Loading ◽  
Measurement Data ◽  
Longitudinal Direction ◽  
Heat Transfer Analysis ◽  
Radiation Model ◽  
Engineering Structures ◽  
Temperature Distributions ◽  
Solar Radiation Model

This paper aims to carry out the condition assessment on solar radiation model and thermal loading of bridges. A modification factor is developed to change the distribution of solar intensities during a whole day. In addition, a new solar radiation model for civil engineering structures is proposed to consider the shelter effects induced by cloud, mountains, and surrounding structures. The heat transfer analysis of bridge components is conducted to calculate the temperature distributions based on the proposed new solar radiation model. By assuming that the temperature along the bridge longitudinal direction is constant, one typical bridge segment is specially studied. Fine finite element models of deck plates and corrugate sheets are constructed to examine the temperature distributions and thermal loading of bridge components. The feasibility and validity of the proposed solar radiation model are investigated through detailed numerical simulation and parametric study. The numerical results are compared with the field measurement data obtained from the long-term monitoring system of the bridge and they shows a very good agreement in terms of temperature distribution in different time instants and in different seasons. The real application verifies effectiveness and validity of the proposed solar radiation and heat transfer analysis.

Study of Heat Transfer and Freezing Time-Temperature Behavior of Individual Pea Grains by Numerical and Experimental Methods

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Manoj Kumar Sharma ◽  
Anil Kumar Pratihar
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Transient Heat Conduction ◽  
Experimental Results ◽  
Heat Transfer Analysis ◽  
Temperature History ◽  
Transient Temperature ◽  
Freezing Time ◽  
Air Stream ◽  
Cooling Air

Abstract The present research demonstrates an accurate and simple numerical model for heat transfer analysis within spherical peas when exposed to the cold air stream in a rectangular duct. The transient heat conduction equation (THCE) is solved for spherical shaped pea grains. A detailed numerical and experimental study of freezing time-temperature history for peas has been carried out. Thermal conductivity and volumetric heat capacity are measured experimentally. Temperature-dependent thermophysical properties are used in the transient temperature prediction of peas throughout the phase change process. Crank–Nicolson method has been used for the formulation of the numerical model. The effect of important parameters, viz., the initial temperature of peas, cooling air temperature, and cooling air velocity over pea samples has been studied both numerically as well as experimentally and it has been found that there is good agreement between numerical and experimental results. The correlation coefficient of linear regression, R2, between numerically predicted and experimental results, is found to be 0.987.

CFD Analysis of Thermally Stratified Flow and Heat Transfer in a PWR Pressurizer Surge Line

2008 ◽  
Author(s):  
Dong Gu Kang ◽  
Jong Chull Jo
Keyword(s):  
Heat Transfer ◽  
Wall Thickness ◽  
Thermal Stratification ◽  
Thermal Stresses ◽  
Complex Geometry ◽  
Heat Transfer Analysis ◽  
Transient Temperature ◽  
Piping System ◽  
Temperature Distributions ◽  
Surge Line

Temperature gradients in the thermally stratified fluid flowing through a pipe may cause undesirable excessive thermal stresses at the pipe wall in the axial, circumferential, and radial directions, which can eventually lead to damages such as deformation, support failure, thermal fatigue, cracking, etc. to the piping systems. Several nuclear power plants have so far experienced such unwelcome mechanical damages to the pressurizer surge lines, feedwater nozzle, high pressure safety injection lines, or residual heat removal lines. In this regard, to determine the transient temperature distributions in the wall of a piping system subjected to internally thermal stratification with accuracy is the essential prerequisite for the assessment of the structural integrity of the piping system subjected to internally thermal stratification. In this study, to predict the transient temperature distributions in the wall of PWR pressurizer surge line with a complex geometry of 3-dimensionally bent piping realistically, 3-dimensional transient CFD calculations involving the conjugate heat transfer analysis are performed for the actual PWR pressurizer surge line subjected to stratified internal flows either during out-surge or in-surge operation using a commercial CFD code. In addition, the wall temperature distributions obtained by taking account of the existence of wall thickness as it is are compared with those by neglecting the existence of wall thickness to identify some requirements for a realistic and conservative thermal analysis.

Thermal Stress Ratchet Check in Piping Analysis

2017 ◽  
Author(s):  
R. Adibi-Asl ◽  
M. Noban ◽  
E. Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Flat Plate ◽  
Material Properties ◽  
Heat Transfer Analysis ◽  
Transient Conditions ◽  
Temperature Distributions ◽  
Temperature Ranges ◽  
Thermal Transient ◽  
Simplified Formula

The ASME B&PV Code, Section III NB-3600 provides a requirement to avoid thermal stress ratcheting under thermal transient conditions. The ratchet check in this code is based on calculating the range of temperature difference between the outside and inside surfaces of the pipe for pairs of load sets. The calculated temperature ranges are then compared with a code equation which is a function of pressure, geometry and material properties. This paper reviews the thermal stress ratchet requirements in ASME Section III Subsection NB with respect to piping analysis. A simplified formula is proposed for thermal stress ratchet check which eliminates the difficulties and ambiguities associate with the formulation provided in the NB-3600 code. The paper also investigates temperature distributions for various components (including flat plate and pipe) by performing heat transfer analysis. The results are compared with the ratchet limit. Using plate solutions to estimate the temperature range of pipe could sometimes give non-conservative results.

Heat Transfer and Stress Analysis of Coke Drum for a Complete Operating Cycle

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Zihui Xia ◽  
Feng Ju ◽  
Pierre Du Plessis
Keyword(s):  
Heat Transfer ◽  
Stress Analysis ◽  
Low Cycle Fatigue ◽  
Measurement Data ◽  
Biaxial Stress ◽  
Heat Transfer Analysis ◽  
Temperature History ◽  
Analysis Model ◽  
Transfer Coefficients ◽  
Operating Cycle

Coke drums experience severe thermal and mechanical loadings during operation, and the reliability and safety of the coke drums are critical to the industry. The objective of this study is to analyze temperature and stress of the coke drum for a complete process cycle. The thermal analysis model of the coke drum is first developed incorporating appropriate boundary conditions. The heat transfer coefficients at the inner surface of the coke drum, which change with the operation stages and the levels of oil filling and water quenching, are determined based on the temperature measurement data at a certain location on the outer surface of the coke drum. The temperature history of the coke drum of a complete cycle is then obtained by finite element heat transfer analysis, and computed temperature data are used for the stress analysis of the coke drum, including both thermal and mechanical loadings. It is found from numerical results that the clad experiences a biaxial stress cycling with maximum value higher than the yield limit of the material, which coincide with the low cycle fatigue failure of the structure.

Sign in / Sign up

Export Citation Format

Share Document