Bio-Heat Transfer in a Model Skin Subject to a Train of Short Pulse Irradiation

2008 ◽  
Author(s):  
Jian Jiao ◽  
Zhixiong Guo
Keyword(s):  
Heat Transfer ◽  
Temperature Rise ◽  
Ultrashort Pulse ◽  
Short Pulse ◽  
Temperature Response ◽  
Biological Tissues ◽  
Skin Tissue ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Pulse Irradiation

Thermal analysis of biological tissues subject to a train of ultrashort pulse irradiations was made of developing a combined time-dependent radiation and conduction bio-heat transfer model. A model skin tissue stratified as three layers with different optical, thermal and physiological properties was considered. Temperature response of the skin tissue exposed to a single ultrashort pulse irradiation was firstly analyzed by the finite volume method in combination with the transient discrete ordinates method. This temperature rise was found to reach pseudo steady state within an extremely short time period in which thermal diffusion is negligible. Since the tissue properties were assumed to be constant during a train of pulse irradiation, this temperature rise subject to a single pulse can be employed for repeated pulses. In the same time, Pennes’ equation was employed to study the bio-heat transfer in the meso-time scale. The effects of pulse strengths and repetition rate on the temperature response in the multi-layer skin tissue were investigated.

Temperature Response in Living Skin Tissue Subject to Convective Heat Flux

2018 ◽  
Vol 387 ◽  
pp. 1-9
Author(s):  
Sanatan Das ◽  
Tilak Kumer Pal ◽  
Rabindra Nath Jana ◽  
Oluwole Daniel Makinde
Keyword(s):  
Heat Transfer ◽  
Biot Number ◽  
Temperature Response ◽  
Bioheat Transfer ◽  
Heat Transfer Analysis ◽  
Skin Tissue ◽  
Tissue Temperature ◽  
Convective Heating ◽  
Transform Method ◽  
Living Tissues

This paper examines the heat transfer in living skin tissue that is subjected to a convective heating. The tissue temperature evolution over time is classically described by the one-dimensional Pennes' bioheat transfer equation which is solved by applying Laplace transform method. The heat transfer analysis on skin tissue (dermis and epidermis) has only been studied defining the Biot number. The result shows that the temperature in skin tissue is less subject to the convected heating skin compared to constant skin temperature. The study also shows that the Biot number has a significant impact on the temperature distribution in the layer of living tissues. This study finds its application in thermal treatment.

Radiation Heat Transfer in Fluidized Beds: A Comparison of Exact and Simplified Approaches

1994 ◽  
Vol 116 (3) ◽  
pp. 652-659 ◽  
Author(s):  
G. Flamant ◽  
J. D. Lu ◽  
B. Variot
Keyword(s):  
Heat Transfer ◽  
Fluidized Beds ◽  
Radiation Heat Transfer ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Radiation Heat ◽  
Flux Divergence ◽  
Transfer Coefficients ◽  
Variable Porosity ◽  
Radiation Exchange

Radiation heat transfer at heat exchanger walls in fluidized beds has never been examined through a complete formulation of the problem. In this paper a wall-to-bed heat transfer model is proposed to account for particle convection, gas convection, and radiation exchange in a variable porosity medium. Momentum, energy, and intensity equations are solved in order to determine the velocity, temperature, radiative heat flux profiles and heat transfer coefficients. The discrete-ordinates method is used to compute the radiative intensity equation and the radiative flux divergence in the energy equation. Both the gray and the non-gray assumptions are considered, as well as dependent and independent scattering. The exact solution obtained is compared with several simplified approaches. Large differences are shown for small particles at high temperature but the simplified solutions are valid for large particle beds. The dependency of radiative contribution on controlling parameters is discussed.

scholarly journals Thermal Analysis of Heat Transfer from Catheters and Implantable Devices to the Blood Flow

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 230
Author(s):  
Hossein Zangooei ◽  
Seyed Ali Mirbozorgi ◽  
Seyedabdollah Mirbozorgi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Blood Flow ◽  
Temperature Rise ◽  
Implantable Devices ◽  
The Body ◽  
Transfer Model ◽  
Governing Equations ◽  
Blood Flow Velocities ◽  
Flow Velocities

Implantable devices, ultrasound imaging catheters, and ablation catheters (such as renal denervation catheters) are biomedical instruments that generate heat in the body. The generated heat can be harmful if the body temperature exceeds the limit of almost 315 K. This paper presents a heat-transfer model and analysis, to evaluate the temperature rise in human blood due to the power loss of medical catheters and implantable devices. The dynamic of the heat transfer is modeled for the blood vessel, at different blood flow velocities. The physics and governing equations of the heat transfer from the implanted energy source to the blood and temperature rise are expressed by developing a Non-Newtonian Carreau–Yasuda fluid model. We used a Finite Element method to solve the governing equations of the established model, considering the boundary conditions and average blood flow velocities of 0–1.4 m/s for the flow of the blood passing over the implanted power source. The results revealed a maximum allowable heat flux of 7500 and 15,000 W/m2 for the blood flow velocities of 0 and 1.4 m/s, respectively. The rise of temperature around the implant or tip of the catheter is slower and disappeared gradually with the blood flow, which allows a higher level of heat flux to be generated. The results of this analysis are concluded in the equation/correlation T=310+H3000(1+e−7V), to estimate and predict the temperature changes as a function of heat flux, H, and the blood flow velocity, V, at the implant/catheter location.

Selection of heat transfer model for describing short-pulse laser heating silica-based sensor

2012 ◽  
Vol 24 (2) ◽  
pp. 285-288
Author(s):  
郝向南 Hao Xiangnan ◽  
聂劲松 Nie Jinsong ◽  
李化 Li Hua ◽  
卞进田 Bian Jintian
Keyword(s):  
Heat Transfer ◽  
Pulse Laser ◽  
Laser Heating ◽  
Short Pulse ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Short Pulse Laser ◽  
Pulse Laser Heating ◽  
Selection Of

scholarly journals Development of heat-pulse sensors for measuring fluxes of water and solutes under the root zone

2016 ◽  
Author(s):  
Tamir Kamai ◽  
Gerard Kluitenberg ◽  
Alon Ben-Gal
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Analytical Solution ◽  
Root Zone ◽  
Large Diameter ◽  
Water Flux ◽  
Temperature Response ◽  
Heat Pulse ◽  
Transfer Model ◽  
Pulse Sensor

The objectives defined for this study were to: (1) develop a heat-pulse sensor and a heat-transfer model for leaching measurement, and (2) conduct laboratory study of the sensor and the methodology to estimate leaching flux. In this study we investigated the feasibility for estimating leachate fluxes with a newly designed heat-pulse (HP) sensor, combining water flux density (WFD) with electrical conductivity (EC) measurements in the same sensor. Whereas previous studies used the conventional heat pulse sensor for these measurements, the focus here was to estimate WFD with a robust sensor, appropriate for field settings, having thick-walled large-diameter probes that would minimize their flexing during and after installation and reduce associated errors. The HP method for measuring WFD in one dimension is based on a three-rod arrangement, aligned in the direction of the flow (vertical for leaching). A heat pulse is released from a center rod and the temperature response is monitored with upstream (US) and downstream (DS) rods. Water moving through the soil caries heat with it, causing differences in temperature response at the US and DS locations. Appropriate theory (e.g., Ren et al., 2000) is then used to determine WFD from the differences in temperature response. In this study, we have constructed sensors with large probes and developed numerical and analytical solutions for approximating the measurement. One-dimensional flow experiments were conducted with WFD ranging between 50 and 700 cm per day. A numerical model was developed to mimic the measurements, and also served for the evaluation of the analytical solution. For estimation WFD, and analytical model was developed to approximate heat transfer in this setting. The analytical solution was based on the work of Knight et al. (2012) and Knight et al. (2016), which suggests that the finite properties of the rods can be captured to a large extent by assuming them to be cylindrical perfect conductors. We found that: (1) the sensor is sensitive for measuring WFD in the investigated range, (2) the numerical model well-represents the sensor measurement, and (2) the analytical approximation could be improved by accounting for water and heat flow divergence by the large rods. 

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