Theoretical and Experimental Studies of Local Tissue Temperature Oscillation Under Hyperthermic Conditions Using Preserved Pig Kidney

2000 ◽  
Author(s):  
Cuiye Chen ◽  
Lisa X. Xu
Keyword(s):  
Heat Transfer ◽  
Experimental Studies ◽  
Temperature Oscillation ◽  
Tissue Temperature ◽  
Surrounding Tissue ◽  
Transient Temperature ◽  
Thermal Bath ◽  
Target Tissue ◽  
Local Tissue ◽  
Pig Kidney

Abstract It has been long recognized that local tissue temperature may osculate due to vascular thermo-regulation under hyperthermic conditions. To effectively heat the target tissue while sparing its surroundings, it is necessary to understand and then to control the temperature oscillation. A model based on the pig kidney vasculature was developed to study the transient temperature variations in the kidney when subjected to heating in a thermal bath. In the medullary region, a vascular model previously developed in (Chen and Xu, 2000) was used to account for the conjugate heat transfer between the paired artery and vein, and their surrounding tissue. Considering that numerous small vessels exist in the cortex region, the Pennes bio-heat transfer equation was used for modeling in this region. A code was written to numerically compute the 3-D transient temperature distribution in the kidney subjected to heating. To examine the validity of the model, experiments were performed to measure the temperatures and perfusion rates using thermistor microprobes in the cortex of the preserved pig kidney. This model will be utilized for future studies to investigate the relationships among the local blood perfusion rate, the heating rate, and the tissue temperature oscillation.

A Vascular Model for Heat Transfer in an Isolated Pig Kidney During Water Bath Heating

2003 ◽  
Vol 125 (5) ◽  
pp. 936-943 ◽  
Author(s):  
Cuiye Chen ◽  
Lisa X. Xu
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Water Bath ◽  
Bioheat Transfer ◽  
Tissue Temperature ◽  
Surrounding Tissue ◽  
Hyperthermia Treatment ◽  
Pig Kidney ◽  
Vascular Model ◽  
Water Bath Heating

Isolated pig kidney has been widely used as a perfused organ phantom in the studies of hyperthermia treatments, as blood perfusion plays an essential role in thermoregulation of living tissues. In this research, a vascular model was built to describe heat transfer in the kidney phantom during water bath heating. The model accounts for conjugate heat transfer between the paired artery and vein, and their surrounding tissue in the renal medulla. Tissue temperature distribution in the cortex was predicted using the Pennes bioheat transfer equation. An analytical solution was obtained and validated experimentally for predicting the steady state temperature distribution in the pig kidney when its surface kept at a uniform constant temperature. Results showed that local perfusion rate significantly affected tissue temperature distributions. Since blood flow is the driving force of tissue temperature oscillations during hyperthermia, the newly developed vascular model provides a useful tool for hyperthermia treatment optimization using the kidney phantom model.

Analysis of Dual Phase Lag Heat Conduction in Gold Nanoparticle Based Hyperthermia Treatment

2008 ◽  
Author(s):  
C. Liu ◽  
B. Q. Li ◽  
C. Mi
Keyword(s):  
Heat Conduction ◽  
Gold Nanoparticle ◽  
Tissue Temperature ◽  
Surrounding Tissue ◽  
Transient Temperature ◽  
Short Time Scale ◽  
Phase Lag ◽  
Dual Phase ◽  
Hyperthermia Treatment ◽  
Lag Model

This paper addresses the fast-transient heat conduction phenomena of a gold nanoparticle embedded in cancerous tissue in hyperthermia treatment. Dual phase lag model in spherical coordinates was employed and a semi-analytical solution of 1-D non-homogenous dual phase lag equation was presented. Results show that transient temperature depends dramatically on the lagging characteristic time of the surrounding tissue. Temperature predicted by dual phase lag model greatly exceeds that predicted by a classical diffusion model, with either a constant source or a pulsed source. This phenomenon is mainly attributed by the phase lag of heat flux of tissue. The overheating in short time scale and the consequent biological effect needs to be paid more attention in the related study.

Sensitivity Analysis of One-Dimensional Heat Transfer in Tissue With Temperature-Dependent Perfusion

1997 ◽  
Vol 119 (1) ◽  
pp. 77-80 ◽  
Author(s):  
C. R. Davies ◽  
G. M. Saidel ◽  
H. Harasaki
Keyword(s):  
Heat Transfer ◽  
Sensitivity Analysis ◽  
Heated Surface ◽  
Experimental Studies ◽  
Total Artificial Heart ◽  
Tissue Temperature ◽  
Model Parameters ◽  
Temperature Dependent ◽  
One Dimensional

Design criteria for implantable, heat-generating devices such as the total artificial heart require the determination of safe thresholds for chronic heating. This involves in-vivo experiments in which tissue temperature distributions are obtained in response to known heat sources. Prior to experimental studies, simulation using a mathematical model can help optimize the design of experiments. In this paper, a theoretical analysis of heat transfer is presented that describes the dynamic, one-dimensional distribution of temperature from a heated surface. Loss of heat by perfusion is represented by temperature-independent and temperature-dependent terms that can reflect changes in local control of blood flow. Model simulations using physiologically appropriate parameter values indicate that the temperature elevation profile caused by a heated surface adjacent to tissue may extend several centimeters into the tissue. Furthermore, sensitivity analysis indicates the conditions under which temperature profiles are sensitive to changes in thermal diffusivity and perfusion parameters. This information provides the basis for estimation of model parameters in different tissues and for prediction of the thermal responses of these tissues.

Measurements and Predictions of Steady-State and Transient Temperature Distributions of a Gasoline Engine

2011 ◽  
Vol 128-129 ◽  
pp. 620-624 ◽  
Author(s):  
Hai Bo Chen ◽  
Zhao Cheng Yuan ◽  
Wei Lu ◽  
Jin Lei Cai
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Gasoline Engine ◽  
Mutual Influence ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Transient Temperature ◽  
Operation Condition ◽  
Ic Engine ◽  
Temperature Distributions

During the design process of Internal Combustion (IC) engine, what is often taken into consideration is the temperature of the important heated parts. The temperature distributions are the primary causes of thermal fatigue in the engine. A combined experimental and analytical approach was followed in this work to study temperature distributions of gasoline engine under steady-state and transient operation condition. Experimental studies were conducted to measure temperatures under a series of steady-state and transient operating conditions. A comparison of the steady-state and transient measurements has been made and the character of transient temperature distributions is concluded. Subsequently, a calculation analysis was conducted to predict the detailed temperature distributions. Solid-Fluid whole conjugated heat transfer method is applied in the numerical calculation, which can take the mutual influence both the fluid flow and the heat transfer into account. The predicted temperatures met well with the measurements. Furthermore, the predicted location of coolant boiling phenomena in the water jacket can be made certain. This can give some suggests for the further observation experiment of boiling heat transfer.

Theoretical Analysis of the Large Blood Vessel Influence on the Local Tissue Temperature Decay After Pulse Heating

1993 ◽  
Vol 115 (2) ◽  
pp. 175-179 ◽  
Author(s):  
L. X. Xu ◽  
M. M. Chen ◽  
K. R. Holmes ◽  
H. Arkin
Keyword(s):  
Temperature Field ◽  
Blood Vessel ◽  
Point Source ◽  
Blood Perfusion ◽  
Tissue Temperature ◽  
Surrounding Tissue ◽  
Heating Pulse ◽  
Local Tissue ◽  
Large Blood Vessel ◽  
Temperature Decay

The influence of a large blood vessel (larger than 500 μm in diameter) on the local tissue temperature decay following a point source heating pulse was determined numerically using a sink/source method. It was assumed that the vessel was large enough so that the temperature of blood flowing within it remained essentially constant and was unaffected by any local tissue temperature transients. After the insertion of a point source heating pulse, the vessel influence on the local tissue transient temperature field was estimated by representing the vessel as a set of negative fictitious instantaneous heat sources with strength just sufficient to maintain the vessel at a constant temperature. In the surrounding tissue, the Pennes’ tissue heat transfer equation was used to describe the temperature field. Computations have been performed for a range of vessel sizes, probe-vessel spacings and local blood perfusion rates. It was found that the influence of a large vessel on the local tissue temperature decay is more sensitive to its size and location rather than to the local blood perfusion rate. For a heating pulse of 3s duration and 5 mW of power, there is a critical probe-vessel center distance 7R (R, vessel radius) beyond which the larger vessel influence on tissue temperature at the probe can be neglected.

A New Simplified Bioheat Equation for the Effect of Blood Flow on Local Average Tissue Temperature

1985 ◽  
Vol 107 (2) ◽  
pp. 131-139 ◽  
Author(s):  
S. Weinbaum ◽  
L. M. Jiji
Keyword(s):  
Heat Transfer ◽  
Blood Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Blood Perfusion ◽  
Basic Mechanism ◽  
Simple Expression ◽  
Tissue Temperature ◽  
Bioheat Equation ◽  
Countercurrent Exchange

A new simplified three-dimensional bioheat equation is derived to describe the effect of blood flow on blood-tissue heat transfer. In two recent theoretical and experimental studies [1, 2] the authors have demonstrated that the so-called isotropic blood perfusion term in the existing bioheat equation is negligible because of the microvascular organization, and that the primary mechanism for blood-tissue energy exchange is incomplete countercurrent exchange in the thermally significant microvessels. The new theory to describe this basic mechanism shows that the vascularization of tissue causes it to behave as an anisotropic heat transfer medium. A remarkably simple expression is derived for the tensor conductivity of the tissue as a function of the local vascular geometry and flow velocity in the thermally significant countercurrent vessels. It is also shown that directed as opposed to isotropic blood perfusion between the countercurrent vessels can have a significant influence on heat transfer in regions where the countercurrent vessels are under 70-μm diameter. The new bioheat equation also describes this mechanism.

Method and tools for determining heat transfer coefficients in organic liquids and solutions

2020 ◽  
pp. 45-55
Author(s):  
Aleksandr S. MYAKOCHIN ◽  
Petr V. NIKITIN ◽  
Sergey Yu. POBEREZHSKIY ◽  
Anna A. SHKURATENKO
Keyword(s):  
Heat Transfer ◽  
Experimental Studies ◽  
Pulse Method ◽  
Organic Liquids ◽  
Transfer Coefficients ◽  
Resistance Thermometer ◽  
Film Sensor ◽  
Heat Transfer Coefficients ◽  
Aerospace Technology ◽  
New Generation

The paper presents a method, tools and a newly developed algorithm for experimentally determining heat transfer coefficients in organic liquids and solutions. This work is made relevant by the problem of development of a new generation of aerospace technology. In this connection, improvements have been made to the pulse method of determining heat transfer coefficients that is based on the use of a micron-thick film sensor. The measurement setup was modified. A math model was constructed for the measuring sensor. Algorithms were developed for conducting the experiment and processing measurement results to determine heat transfer coefficients. Experimental uncertainties were analyzed. The paper provides results of experimental studies on certain organic liquids. The authors believe that the material presented in the paper will find application in research conducted at research institutions, engineering offices and universities, among researches, postgraduates and students. Key words: thermal and physical characteristics, organic liquids and their solutions, film-type electrical resistor, thin-film temperature sensor, voltage pulse, resistance thermometer, irregular heat transfer regime.

Experimental studies on micro-channel heat sink with different heat transfer fluid

2021 ◽  
Author(s):  
M. P. Dhanishk ◽  
P. Selvakumar ◽  
V. Ashwin ◽  
P. N. ArunKumar
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Experimental Studies ◽  
Heat Transfer Fluid ◽  
Micro Channel
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