Modeling and Estimating Simulated Burn Depth Using the Perfusion and Thermal Resistance Probe

2013 ◽  
Vol 7 (3) ◽  
Author(s):  
Abdusalam Al-Khwaji ◽  
Brian Vick ◽  
Tom Diller
Keyword(s):  
Mathematical Model ◽  
Heat Flux ◽  
Parameter Estimation ◽  
Thermal Resistance ◽  
Contact Resistance ◽  
Core Temperature ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Blood Perfusion ◽  
Thermal Event

A new thermal perfusion probe operates by imposing a thermal event on the tissue surface and directly measuring the temperature and heat flux response of the tissue with a small sensor. The thermal event is created by convectively cooling the surface with a small group of impinging jets using room temperature air. The hypothesis of this research is that this sensor can be used to provide practical burn characterization of depth and severity by determining the thickness of nonperfused tissue. To demonstrate this capability the measurement system was tested with a phantom tissue that simulates the blood perfusion of tissue. Different thicknesses of plastic were used at the surface to mimic layers of dead tissue. A mathematical model developed by Alkhwaji et al. (2012, “New Mathematical Model to Estimate Tissue Blood Perfusion, Thermal Contact Resistance and Core Temperature,” ASME J. Biomech. Eng., 134, p. 081004) is used to determine the effective values of blood perfusion, core temperature, and thermal resistance from the thermal measurements. The analytical solutions of the Pennes bioheat equation using the Green's function method is coupled with an efficient parameter estimation procedure to minimize the error between measured and analytical heat flux. Seven different thicknesses of plastic were used along with three different flow rates of perfusate to simulate burned skin of the phantom perfusion system. The resulting values of thermal resistance are a combination of the plastic resistance and thermal contact resistance between the sensor and plastic surface. Even with the uncertainty of sensor placement on the surface, the complete set of thermal resistance measurements correlate well with the layer thickness. The values are also nearly independent of the flow rate of the perfusate, which shows that the parameter estimation can successfully separate these two parameters. These results with simulated burns show the value of this minimally invasive technique to measure the thickness of nonperfused layers. This will encourage further work with this method on actual tissue burns.

New Mathematical Model to Estimate Tissue Blood Perfusion, Thermal Contact Resistance and Core Temperature

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Abdusalam Alkhwaji ◽  
Brian Vick ◽  
Tom Diller
Keyword(s):  
Heat Flux ◽  
Parameter Estimation ◽  
Contact Resistance ◽  
Core Temperature ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Simulated Data ◽  
Thermal Conditions ◽  
Blood Perfusion ◽  
Simple Parameter

Analytical solutions were developed based on the Green’s function method to describe heat transfer in tissue including the effects of blood perfusion. These one-dimensional transient solutions were used with a simple parameter estimation technique and experimental measurements of temperature and heat flux at the surface of simulated tissue. It was demonstrated how such surface measurements can be used during step changes in the surface thermal conditions to estimate the value of three important parameters: blood perfusion (wb), thermal contact resistance (R″), and core temperature of the tissue (Tcore). The new models were tested against finite-difference solutions of thermal events on the surface to show the validity of the analytical solution. Simulated data was used to demonstrate the response of the model in predicting optimal parameters from noisy temperature and heat flux measurements. Finally, the analytical model and simple parameter estimation routine were used with actual experimental data from perfusion in phantom tissue. The model was shown to provide a very good match with the data curves. This demonstrated the first time that all three of these important parameters (wb, R″, and Tcore) have simultaneously been estimated from a single set of thermal measurements at the surface of tissue.

Design and Verification of a Low-Powered Pre-Programmable In-Package Temperature Controller

2006 ◽  
Author(s):  
Hyeun-Su Kim ◽  
Hsien-Hsin Liao ◽  
Byeong-hee Lee ◽  
Thomas W. Kenny
Keyword(s):  
Thermal Resistance ◽  
Contact Resistance ◽  
Temperature Change ◽  
Thermal Contact Resistance ◽  
Operating Temperature ◽  
Electrostatic Force ◽  
Thermal Contact ◽  
Temperature Regulator ◽  
Thermal Resistors ◽  
Device Test

A zero power passive temperature regulator has been studied and designed to maintain electric chip operating temperature using a variable thermal resistor. Apart from the passive temperature regulator design, we also present active variable thermal resistors using electrostatic force to actuate the device. Test samples were fabricated to verify these two designs and we observed the temperature change of a heated chip due to thermal resistance changes. This study estimated and measured the thermal contact resistance and the force required to remove it.

Soil Heat Flux Plates: Heat Flow Distortion and Thermal Contact Resistance

2007 ◽  
Vol 99 (1) ◽  
pp. 304-310 ◽  
Author(s):  
Thomas J. Sauer ◽  
Tyson E. Ochsner ◽  
Robert Horton
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Soil Heat Flux ◽  
Flow Distortion

scholarly journals Measurement of the Thermophysical Properties of Anisotropic Insulation Materials with Consideration of the Effect of Thermal Contact Resistance

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1353 ◽  
Author(s):  
Dongxu Han ◽  
Kai Yue ◽  
Liang Cheng ◽  
Xuri Yang ◽  
Xinxin Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Maximum Deviation ◽  
Insulation Materials ◽  
Steady State Method ◽  
Different Temperatures

A novel method involving the effect of thermal contact resistance (TCR) was proposed using a plane heat source smaller than the measured samples for improving measurement accuracy of the simultaneous determination of in-plane and cross-plane thermal conductivities and the volumetric heat capacity of anisotropic materials. The heat transfer during the measurement process was mathematically modeled in a 3D Cartesian coordinate system. The temperature distribution inside the sample was analytically derived by applying Laplace transform and the variables separation method. A multiparameter estimation algorithm was developed on the basis of the sensitivity analysis of the parameters to simultaneously estimate the measured parameters. The correctness of the algorithm was verified by performing simulation experiments. The thermophysical parameters of insulating materials were experimentally measured using the proposed method at different temperatures and pressures. Fiber glass and ceramic insulation materials were tested at room temperature. The measured results showed that the relative error was 1.6% less than the standard value and proved the accuracy of the proposed method. The TCRs measured at different pressures were compared with those obtained using the steady-state method, and the maximum deviation was 8.5%. The thermal conductivity obtained with the contact thermal resistance was smaller than that without the thermal resistance. The measurement results for the anisotropic silica aerogels at different temperatures and pressures revealed that the thermal conductivity and thermal contact conductance increased as temperature and pressure increased.

Development of an Experimental Procedure for Thermal Contact Resistance Estimation at the Glass/Metal Contact Interface

2013 ◽  
Vol 6 (2) ◽  
Author(s):  
B. Abdulhay ◽  
B. Bourouga ◽  
F. Alzetto ◽  
C. Challita
Keyword(s):  
Heat Flux ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Thermal Conditions ◽  
Metal Contact ◽  
Contact Interface ◽  
Equivalent Thermal Conductivity ◽  
Experimental Procedure ◽  
Glass Metal

In this paper, an experimental device is designed and developed in order to estimate thermal conditions at the glass/metal contact interface. This device is made of two parts: The upper part contains the tool (piston) made of bronze and a heating device to raise the temperature of the piston to 700 °C. The lower part is composed of a lead crucible and a glass sample. The assembly is provided with a heating system, an induction furnace of 6 kW for heating the glass up to 950 °C. The developed experimental procedure has permitted the estimation of the thermal contact resistance (TCR) using a developed measurement principle based on the inverse technique developed by Beck et al. (1985, Inverse Heat Conduction: III Posed Problems, Wiley Inter-science, New York). The semitransparent character of the glass has been taken into account by an additional radiative heat flux and an equivalent thermal conductivity. After the set-up tests, reproducibility experiments for a specific contact pressure have been carried out. Results show a good repeatability of the registered and estimated parameters such as the piston surface temperature, heat flux density, and TCR. The estimated value of TCR reaches 2 × 10−3 K m2/W with a maximum dispersion that does not exceed 6%.

Modeling and Experimental Characterization of Metal Microtextured Thermal Interface Materials

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
R. Kempers ◽  
A. M. Lyons ◽  
A. J. Robinson
Keyword(s):  
Thermal Resistance ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Thermal Interface Material ◽  
Small Scale ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Main Challenge

A metal microtextured thermal interface material (MMT-TIM) has been proposed to address some of the shortcomings of conventional TIMs. These materials consist of arrays of small-scale metal features that plastically deform when compressed between mating surfaces, conforming to the surface asperities of the contacting bodies and resulting in a low-thermal resistance assembly. The present work details the development of an accurate thermal model to predict the thermal resistance and effective thermal conductivity of the assembly (including contact and bulk thermal properties) as the MMT-TIMs undergo large plastic deformations. The main challenge of characterizing the thermal contact resistance of these structures was addressed by employing a numerical model to characterize the bulk thermal resistance and estimate the contribution of thermal contact resistance. Furthermore, a correlation that relates electrical and thermal contact resistance for these MMT-TIMs was developed that adequately predicted MMT-TIM properties for several different geometries. A comparison to a commercially available graphite TIM is made as well as suggestions for optimizing future MMT-TIM designs.

Evaluation of Thermal Contact Resistance Under High Heat Flux Considering Material Hardness Using Numerical Analysis

2018 ◽  
Vol 2018 (0) ◽  
pp. 0215
Author(s):  
Risako Kibushi ◽  
Kazuhisa Yuki ◽  
Tomoyuki Hatakeyama ◽  
Noriyuki Unno ◽  
Toshio Tomimuta ◽  
...  
Keyword(s):  
Heat Flux ◽  
Numerical Analysis ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
High Heat ◽  
High Heat Flux ◽  
Material Hardness
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