scholarly journals Application of RC delay time for estimation of thermal properties

2021 ◽  
Vol 2116 (1) ◽  
pp. 012111
Author(s):  
Priyanka Jena ◽  
Rajesh Gupta
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Thermal Properties ◽  
Delay Time ◽  
Thermal System ◽  
Inverse Heat Transfer ◽  
Conductivity Range ◽  
Rc Circuit ◽  
Transfer Problems ◽  
Rc Delay

Abstract The analogy between the electrical and thermal system has been extensively used to solve different kinds of direct heat transfer problems. However, this analogy has not been explored much to obtain solutions of inverse heat transfer problems like estimation of thermal properties. This paper presents an approach of estimation of thermal properties using the correspondence between the thermal and electrical domains by exploiting the concept of RC delay time in the resistance-capacitance (RC) circuit. Simulations and experiments have been performed on stainless steel and glass samples to show the applicability of the proposed approach for materials belonging to different conductivity range.

scholarly journals Solution to Two-Dimensional Steady Inverse Heat Transfer Problems with Interior Heat Source Based on the Conjugate Gradient Method

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Shoubin Wang ◽  
Li Zhang ◽  
Xiaogang Sun ◽  
Huangchao Jia
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Conjugate Gradient Method ◽  
Conjugate Gradient ◽  
Gradient Method ◽  
Measuring Error ◽  
Two Dimensional ◽  
Inverse Heat Transfer ◽  
Heat Transfer System ◽  
Transfer Problems

The compound variable inverse problem which comprises boundary temperature distribution and surface convective heat conduction coefficient of two-dimensional steady heat transfer system with inner heat source is studied in this paper applying the conjugate gradient method. The introduction of complex variable to solve the gradient matrix of the objective function obtains more precise inversion results. This paper applies boundary element method to solve the temperature calculation of discrete points in forward problems. The factors of measuring error and the number of measuring points zero error which impact the measurement result are discussed and compared with L-MM method in inverse problems. Instance calculation and analysis prove that the method applied in this paper still has good effectiveness and accuracy even if measurement error exists and the boundary measurement points’ number is reduced. The comparison indicates that the influence of error on the inversion solution can be minimized effectively using this method.

Thermal Conductivity and Specific Heat Evaluation of Tissue Using Laser

2020 ◽  
Vol 1002 ◽  
pp. 303-310
Author(s):  
Sudad Issam Younis ◽  
Haqi I. Qatta ◽  
Mohammed Jalal Abdul Razzaq ◽  
Khalid S. Shibib
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Iterative Procedure ◽  
Input Data ◽  
Maximum Error ◽  
Heat Transfer Analysis ◽  
Long Wavelength ◽  
Inverse Heat Transfer

In this work, an inverse heat transfer analysis was used to determine thermal conductivity and specific heat of tissue using special iteration. A laser with a long wavelength was utilized to impose heat to the tissue. The heat that induced in the sample causes an increase in the temperature of a tissue which is measured by a thermocouple. The readings were used together with that analytically obtained from the solution of the heat equation in an iterative procedure to obtain the thermal properties of tissue. By using this method, accurate thermal conductivity and specific heat of tissue could be obtained. It was found that the maximum error in output result and the error in input data were in the same order and that there was a linear relationship between output and input errors.

Predicting Thermal System Performance and Estimating Parameters for Systems Burdened With Uncertainties and Noise Using Hierarchical Bayesian Inference

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
A. F. Emery ◽  
D. Bardot
Keyword(s):  
Heat Transfer ◽  
System Performance ◽  
Taylor Series Expansion ◽  
Heat Losses ◽  
Thermal System ◽  
Computing Power ◽  
Bayesian Hierarchical ◽  
Hierarchical Bayesian Inference ◽  
Transfer Problems ◽  
The Bayesian Approach

The precision of estimates of system performance and of parameters that affect the performance is often based upon the standard deviation obtained from the usual equation for the propagation of variances derived from a Taylor series expansion. With ever increasing computing power it is now possible to utilize the Bayesian hierarchical approach to yield improved estimates of the precision. Although quite popular in the statistical community, the Bayesian approach has not been widely used in the heat transfer and fluid mechanics communities because of its complexity and subjectivity. The paper develops the necessary equations and applies them to two typical heat transfer problems, measurement of conductivity with heat losses and heat transfer from a fin. Because of the heat loss the probability distribution of the conductivity is far from Gaussian. Using this conductivity distribution for the fin gives a very long tailed distribution for the heat transfer from the fin.

scholarly journals SOLVING TRANSIENT INVERSE HEAT TRANSFER PROBLEMS IN COMPLEX GEOMETRIES USING PHYSICS-GUIDED NEURAL NETWORKS (PGNN)

2021 ◽  
Vol 2021 (3) ◽  
pp. 4540-4547
Author(s):  
D. Emonts ◽  
◽  
J. Yang ◽  
R. H. Schmitt ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Input Parameter ◽  
Temperature Fields ◽  
Elastic Behavior ◽  
Transient Temperature ◽  
Complex Geometries ◽  
Inverse Heat Transfer ◽  
Geometric Inspection ◽  
Transfer Problems

Temporally and spatially unstable thermal conditions lead to transient or inhomogeneous thermo-elastic behavior of workpieces during manufacturing or geometric inspection. Temperature monitoring by means of sensors consign transient temperature fields, but do not yield information about the heat flow acting as thermal boundary condition, which is a relevant input parameter for nearly any thermal simulation. Addressing the need for efficient methods, the authors propose an approach to solve inverse heat transfer problems in complex geometries. In the presented study, locally acting heat loads are experimentally investigated based on virtual demonstrators running in FEM. The conducted method shows high potential for transient heat flow modelling in terms of accuracy and computational efficiency.

Measuring Heat Transfer From Firebrands to Surfaces

2020 ◽  
Author(s):  
Elias Bearinger ◽  
Brian Lattimer ◽  
Jonathan Hodges ◽  
Christian Rippe
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Stainless Steel ◽  
Steel Plate ◽  
Radiant Energy ◽  
Heat Fluxes ◽  
Quartz Plate ◽  
Steel Plates ◽  
Inverse Heat Transfer ◽  
Flux Measurements

Abstract Firebrands are an important mechanism of fire spread and one of the primary ways in which wildland fires ignite structures. Inverse heat transfer using thin steel plates has been shown to be an effective method for measuring heat transfer distributions from firebrands. To fully understand the dynamic process of heat transfer from firebrands to surfaces; however, it is necessary to view the underside of the firebrands, which is not possible through a steel plate. This work develops a method of inverse heat transfer using a visually transparent quartz plate and a long-wave (7.5–14.0 μm) infrared camera to facilitate visual access to the firebrands from all angles. The heat flux measurements using a quartz plate were compared with heat flux measurements using a steel plate and finite element heat transfer simulations for radiation-dominant tests using heater panels. Additionally, heat transfer measurements using cuboidal oak firebrands were conducted using both the quartz and steel plates. A corrective factor was developed based on the ratio of the effective emissivity of the quartz and stainless-steel plates at typical firebrand temperatures. The measured heat fluxes were within 1–6% after correcting for radiant energy transmitted through the quartz which was absorbed by the stainless-steel plate.

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