Inverse heat transfer analysis of a functionally graded fin to estimate time-dependent base heat flux and temperature distributions

2012 ◽  
Vol 57 ◽  
pp. 1-7 ◽  
Author(s):  
Haw-Long Lee ◽  
Win-Jin Chang ◽  
Wen-Lih Chen ◽  
Yu-Ching Yang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Functionally Graded ◽  
Time Dependent ◽  
Heat Transfer Analysis ◽  
Temperature Distributions ◽  
Inverse Heat Transfer

Heat Transfer Analysis of Laminar Pulsating Flow in a Rectangular Channel Using Infrared Thermography

2021 ◽  
Author(s):  
Richard Blythman ◽  
Sajad Alimohammadi ◽  
Nicholas Jeffers ◽  
Darina B. Murray ◽  
Tim Persoons
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Analytical Solution ◽  
Local Time ◽  
Rectangular Channel ◽  
Pulsating Flow ◽  
Time Dependent ◽  
Heat Transfer Analysis ◽  
Flux Boundary Condition ◽  
Hydrodynamic Behaviour

Abstract While numerous applied studies have successfully demonstrated the feasibility of unsteady cooling solutions, a consensus has yet to be reached on the local instantaneous conditions that result in heat transfer enhancement. The current work aims to experimentally validate a recent analytical solution (on a local time-dependent basis) for the common flow condition of a fully-developed incompressible pulsating flow in a uniformly-heated vessel. The experimental setup is found to approximate the ideal constant heat flux boundary condition well, especially for the decoupled unsteady scenario where the amplitude of the most significant secondary contributions (capacitance and lateral conduction) amounts to 1.2% and 0.2% of the generated heat flux, respectively. Overall, the experimental measurements for temperature and heat flux oscillations are found to coincide well with a recent analytical solution to the energy equation by the authors. Furthermore, local time-dependent heat flux enhancements and degradations are observed to be qualitatively similar to those of wall shear stress from a previous study, suggesting that the thermal performance is indeed influenced by hydrodynamic behaviour.

Inverse Heat Transfer Analysis of Grinding, Part 1: Methods

1996 ◽  
Vol 118 (1) ◽  
pp. 137-142 ◽  
Author(s):  
C. Guo ◽  
S. Malkin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Convection Heat Transfer ◽  
Temperature Measurements ◽  
Heat Transfer Analysis ◽  
Estimation Accuracy ◽  
Convection Heat ◽  
Workpiece Surface ◽  
Inverse Heat Transfer ◽  
Accuracy And Stability

Thermal analyses of the grinding process generally require assumptions concerning the distributions of the heat flux to the workpiece within the grinding zone and convective cooling outside the grinding zone. The present work is concerned with the use of inverse heat transfer methods to estimate the heat flux and convection heat transfer coefficient distributions on the workpiece surface during straight surface grinding from temperature measurements within the workpiece. In the present paper, three inverse heat transfer methods are developed: temperature matching, integral, and sequential methods. Each method is evaluated for accuracy and stability using simulated temperature data. The selection of the sampling frequency of the temperature measurements and location of the temperature sensor are found to be critical for both estimation accuracy and stability. In a second paper, these inverse heat transfer methods are applied to estimate the distributions of the heat flux and convection heat transfer coefficients on the workpiece surface for grinding of steels with aluminum oxide and CBN abrasive wheels.

Inverse Heat Transfer Analysis of Grinding, Part 2: Applications

1996 ◽  
Vol 118 (1) ◽  
pp. 143-149 ◽  
Author(s):  
C. Guo ◽  
S. Malkin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Contact Length ◽  
Heat Transfer Analysis ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient ◽  
Inverse Heat Transfer

Distributions of the heat flux to the workpiece and the convection heat transfer coefficient on the workpiece surface during straight surface grinding are estimated from measured temperatures in the workpiece subsurface using inverse heat transfer methods developed in Part 1. The results indicate that the heat flux to the workpiece is distributed approximately linearly (triangular heat source) along the grinding zone with about 70 to 75 percent of the total energy transported as heat to the workpiece for grinding of steels with a conventional aluminum oxide wheel and only about 20 percent with CBN superabrasive wheels. The wheel-workpiece contact length corresponding to the region of positive heat flux to the workpiece is found to be generally close to but slightly longer than the theoretical geometric contact length. The convection heat transfer coefficient for cooling by the applied grinding fluid is greatest just behind the trailing edge of the grinding zone where fluid is directly applied, and negligible ahead of the grinding zone.

Characterization of Tissue Thermal Conductivity During a Tissue Joining Process

2016 ◽  
Author(s):  
Che-Hao Yang ◽  
Yang Liu ◽  
Wei Li ◽  
Roland K. Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Tissue Sample ◽  
Heat Transfer Analysis ◽  
Vessel Sealing ◽  
Inverse Heat Transfer ◽  
Thermal Spread ◽  
Higher Temperature ◽  
Postoperative Problems ◽  
Joining Process

Electrosurgical vessel sealing, a tissue joining process, has been widely used in surgical procedures, such as prostatectomies for bleeding control. The heat generated during the process may cause thermal damages to the surrounding tissues which can lead to detrimental postoperative problems. Having better understanding about the thermal spread helps to minimize these undesired thermal damages. The purpose of this study is to investigate the changes of tissue thermal conductivity during the joining process. We propose a hybrid method combining experimental measurement with inverse heat transfer analysis to determine thermal conductivity of thin tissue sample. Instead of self-heating the tissue by the thermistor, we apply an external cold boundary on the other side of the tissue sample to stimulate a higher temperature gradient without denaturing the tissue in comparison to the heated method. The inverse heat transfer technique was then applied to determine the tissue thermal conductivity. Tissue thermal conductivity at different levels (0%, 25%, 50%, 75%, and 100%) of the joining process was measured. The results show a decreasing trend in tissue thermal conductivity with increasing joining level. When the tissue is fully joined, an average of 60% reduction in tissue thermal conductivity was found.

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