Influence of Brazing on the Heat Transfer Performance of Fins in Radiators

2000 ◽  
Author(s):  
Bengt Sundén ◽  
Andreas Abdon ◽  
Daniel Eriksson
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Detrimental Effect ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Two Dimensional ◽  
Air Gaps ◽  
One Dimensional ◽  
Temperature Distributions ◽  
Braze Joint

Abstract The performance of a radiator copper fin is considered as the braze joint between the fin and the brass tube is not perfect. The influence of different thermophysical properties of the brazing materials, created intermetallic compounds and possible air gaps is considered. Numerical methods for both two-dimensional and one-dimensional calculations have been developed. The finite volume technique is applied and in the two-dimensional case, boundary fitted coordinates are used. Heat conduction in the fin and braze joint coupled with convective heat transfer in a gas stream is analysed. Results in terms of fin temperature distributions and fin efficiencies are provided. It is found that the detrimental effect of a poor braze joint is not as large as reported previously in the literature.

Numerical Analysis of Heat Exchangers Used in a Liquid Piston Compressor Using a One-Dimensional Model With an Embedded Two-Dimensional Submodel

2014 ◽  
Author(s):  
Chao Zhang ◽  
Jacob Wieberdink ◽  
Terrence W. Simon ◽  
Perry Y. Li ◽  
James Van de Ven ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Conduction ◽  
Heat Exchangers ◽  
Piston Compressor ◽  
Two Dimensional ◽  
Dimensional Model ◽  
One Dimensional ◽  
Temperature Distributions ◽  
Liquid Piston

The present study presents a one-dimensional liquid-piston compressor model with an embedded two-dimensional submodel. The submodel is for calculating heat conduction across a representative internal plate of a porous heat exchanger matrix within the compression space. The liquid-piston compressor is used for Compressed Air Energy Storage (CAES). Porous-media-type heat exchangers are inserted in the compressor to absorb heat from air as it is compressed. Compression without heat transfer typically results in a temperature rise of a gas and a drop in efficiency, for the elevated temperature leads to wasted thermal energy, due to cooling during subsequent cooling back to ambient temperature. The use of heat exchangers can reduce the air temperature rise during the compression period. A typical numerical model of a heat exchanger is a one-dimensional simplification of the two-energy-equation porous media model. The present authors proposed a one-dimensional model that incorporates the Volume of Fluid (VOF) method for application to the two-phase flow, liquid piston compressor with exchanger inserts. Important to calculating temperature distributions in both the solid and fluid components of the mixture is heat transfer between the two, which depends on the local temperature values, geometry, and the velocity of fluid through the matrix. In the one-dimensional model, although the axial temperatures vary, the solid is treated as having a uniform temperature distribution across the plate at any axial location. This may be in line with the physics of flow in most heat exchangers, especially when the exchangers are made of metal with high thermal conductivity. However, it must be noted that for application to CAES, the gas temperature in the compression chamber rises rapidly during compression and the core of the solid wall may heat up to a different temperature than that of the surface, depending on the geometry, solid material of the exchanger and fluid flow situation. Therefore, a new, one-dimensional model with embedded two-dimensional submodel is developed to consider two-dimensional heat conduction in a representative solid plate. The VOF concept is used in the model to handle the moving liquid-gas interface (liquid piston). The model gives accurate solutions of temperature distributions in the liquid piston compression chamber. Six different heat exchangers with different length scales and different materials are simulated and compared.

Heat conduction in double-walled carbon nanotubes with intertube additional carbon atoms

2015 ◽  
Vol 17 (25) ◽  
pp. 16476-16482 ◽  
Author(s):  
Liu Cui ◽  
Yanhui Feng ◽  
Peng Tan ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Heat Conduction ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Reduction Mechanisms ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Theoretical insights into the heat transfer performance and its reduction mechanisms in double-walled carbon nanotubes with intertube additional carbon atoms.

A Numerical Investigation Into the Heat Transfer Performance and Particle Dynamics of a Compressible, Highly Mass Loaded, High Reynolds Number, Particle Laden Flow

2021 ◽  
Author(s):  
Kyle Hassan ◽  
Robert F. Kunz ◽  
David Hanson ◽  
Michael Manahan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Computational Model ◽  
High Reynolds Number ◽  
Heat Transfer Performance ◽  
Particle Dynamics ◽  
Transfer Performance ◽  
Temperature Distributions ◽  
High Reynolds ◽  
Particle Laden Flow

Abstract In this work, we study the heat transfer performance and particle dynamics of a highly mass loaded, compressible, particle-laden flow in a horizontally-oriented pipe using an Eulerian-Eulerian (two-fluid) computational model. An attendant experimental configuration [1] provides the basis for the study. Specifically, a 17 bar co-flow of nitrogen gas and copper powder are modeled with inlet Reynolds numbers of 3×104, 4.5×104, and 6×104 and mass loadings of 0, 0.5, and 1.0. Eight binned particle sizes were modeled to represent the known powder properties. Significant settling of all particle groups are observed leading to asymmetric temperature distributions. Wall and core flow temperature distributions are observed to agree well with measurements. In high Reynolds number cases, the predictions of the multiphase computational model were satisfactorily aligned with the experimental results. Low Reynolds number model predictions were not as consistent with the experimental measurements.

A Numerical Investigation Into the Heat Transfer Performance and Particle Dynamics of a Compressible, Highly Mass Loaded, High Reynolds Number, Particle Laden Flow

2021 ◽  
Author(s):  
Kyle Hassan ◽  
Robert Kunz ◽  
David Hanson ◽  
Michael Manahan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Computational Model ◽  
High Reynolds Number ◽  
Heat Transfer Performance ◽  
Particle Dynamics ◽  
Transfer Performance ◽  
Temperature Distributions ◽  
High Reynolds ◽  
Particle Laden Flow

Abstract In this work, we study the heat transfer performance and particle dynamics of a highly mass loaded, compressible, particle-laden flow in a horizontally-oriented pipe using an Eulerian-Eulerian (two-fluid) computational model. An attendant experimental configuration [1] provides the basis for the study. Specifically, a 17 bar co-flow of nitrogen gas and copper powder are modeled with inlet Reynolds numbers of 3 × 104, 4.5 × 104, and 6 × 104 and mass loadings of 0, 0.5, and 1.0. Eight binned particle sizes were modeled to represent the known powder properties. Significant settling of all particle groups are observed leading to asymmetric temperature distributions. Wall and core flow temperature distributions are observed to agree well with measurements. In high Reynolds number cases, the predictions of the multiphase computational model were satisfactorily aligned with the experimental results. Low Reynolds number model predictions were not as consistent with the experimental measurements.

Heat Conduction Effect on Oscillating Heat Pipe Operation

2011 ◽  
Author(s):  
C. D. Smoot ◽  
H. B. Ma ◽  
C. Wilson ◽  
L. Greenberg
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Block Design ◽  
Transfer Performance ◽  
Copper Block ◽  
Oscillating Heat Pipe ◽  
Continuous Block ◽  
Adiabatic Section

The effect of heat conduction through the adiabatic section on the oscillating motion and heat transfer performance in an oscillating heat pipe (OHP) was investigated experimentally. Two, closed loop, 6-turn OHPs were constructed; one with a separate copper block for the evaporator and condenser sections (split block design) and one using a single continuous copper block for the evaporator, adiabatic, and condenser sections (continuous block design). The results show that the presence of heat conduction directly from the evaporator wall to the adiabatic section and from the adiabatic section to the condenser of a heat pipe will reduce the oscillating amplitude of the evaporator, adiabatic, and condenser temperatures. It was also found that in addition to a higher level of temperature uniformity, the continuous block design results in better heat transfer performance than a heat pipe without conduction through the adiabatic section.

scholarly journals Constructal Optimization for Cooling a Non-Uniform Heat Generating Radial-Pattern Disc by Conduction

Entropy ◽  
2018 ◽  
Vol 20 (9) ◽  
pp. 685 ◽  
Author(s):  
Jiang You ◽  
Huijun Feng ◽  
Lingen Chen ◽  
Zhihui Xie
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Heat Conduction ◽  
Heat Transfer Performance ◽  
Variable Cross ◽  
Transfer Performance ◽  
Cross Sectional ◽  
Radial Pattern ◽  
Uniform Heat ◽  
Width Coefficient

A heat conduction model in a radial-pattern disc by considering non-uniform heat generation (NUHG) is established in this paper. A series of high conductivity channels (HCCs) are attached on the rim of the disc and extended to its center. Constructal optimizations of the discs with constant and variable cross-sectional HCCs are carried out, respectively, and their maximum temperature differences (MTDs) are minimized based on analytical method and finite element method. Besides, the influences of the NUHG coefficient, HCC number and width coefficient on the optimal results are studied. The results indicate that the deviation of the optimal constructs obtained from the analytical method and finite element method are comparatively slight. When the NUHG coefficient is equal to 10, the minimum MTD of the disc with 25 constant cross-sectional HCCs is specifically reduced by 48.8% compared to that with 10 HCCs. As a result, the heat conduction performance (HCP) of the disc can be efficiently improved by properly increasing the number of HCCs. The minimum MTD of the disc with variable cross-sectional HCC is decreased by 15.0% when the width coefficient is changed from 1 to 4. Therefore, the geometry of variable cross-sectional HCC can be applied in the constructal design of the disc to a better heat transfer performance. The constructal results obtained by investigating the non-uniform heat generating case in this paper can contribute to the design of practical electronic device to a better heat transfer performance.

Study on Optimization of Evaporative Condenser Nozzle with CFD Method

2013 ◽  
Vol 275-277 ◽  
pp. 654-658
Author(s):  
Yue Zhao ◽  
Hong Jian Zhou ◽  
Jing Xie ◽  
Yi Tang ◽  
Chen Miao
Keyword(s):  
Heat Transfer ◽  
Numerical Calculation ◽  
Heat Transfer Performance ◽  
Optimal Structure ◽  
Transfer Performance ◽  
Two Dimensional ◽  
Dimensional Modeling ◽  
Operation Process ◽  
Cfd Method ◽  
Calculation Software

In the evaporative condenser, the shape and structure of the nozzle determines the spraying effect, which affects the overall heat transfer performance of the evaporative condenser. Due to the constraints of its structure, spraying test is difficult in evaporative condenser operation process. The performance of the two types of nozzle spray is simulated by CFD numerical calculation software, using the two-dimensional modeling. The results show that the two-tier shunt platform nozzle sprays more uniformly, the movement of airflow around is relative more regular, the performance of spraying water is more stable. The reference is provided to select the optimal structure of the nozzle under certain conditions.

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