scholarly journals A Generic Bioheat Transfer Thermal Model for a Perfused Tissue

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Devashish Shrivastava ◽  
J. Thomas Vaughan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Rate ◽  
Thermal Model ◽  
Imaging Techniques ◽  
Bioheat Transfer ◽  
Generic Model ◽  
Transfer Model ◽  
Conservation Of Energy ◽  
Simplifying Assumptions

A thermal model was needed to predict temperatures in a perfused tissue, which satisfied the following three criteria. One, the model satisfied conservation of energy. Two, the heat transfer rate from blood vessels to tissue was modeled without following a vessel path. Three, the model applied to any unheated and heated tissue. To meet these criteria, a generic bioheat transfer model (BHTM) was derived here by conserving thermal energy in a heated vascularized finite tissue and by making a few simplifying assumptions. Two linear coupled differential equations were obtained with the following two variables: tissue volume averaged temperature and blood volume averaged temperature. The generic model was compared with the widely employed empirical Pennes’ BHTM. The comparison showed that the Pennes’ perfusion term wCp(1−ε) should be interpreted as a local vasculature dependent heat transfer coefficient term. Suggestions are presented for further adaptations of the general BHTM for specific tissues using imaging techniques and numerical simulations.

Investigation of Ethylene Glycol Heat Transfer Coefficient Trough Double Pipe and Coil Heat Exchanger

2021 ◽  
Vol 874 ◽  
pp. 165-170
Author(s):  
Sri Wuryanti ◽  
Tina Mulya Gantina ◽  
Indriyani
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Ethylene Glycol ◽  
Transfer Coefficient ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Test System ◽  
Double Pipe ◽  
The Heat Transfer Coefficient ◽  
Outer Pipe

The research objective is to assemble a convection test system which acts as a heat exchanger (HE) and test its applicability using ethylene glycol. A Double Pipe (DP)-type HE consists of an inner pipe surrounded by an outer pipe (annulus) whereas a Coil-type HE composed of a coil surrounded by an outer pipe. Water flows through the outer pipe in both types of HE, while ethylene glycol flows through the inner piper or coil. HE in combination with other components (such as) forms a convection test system. The applicability of the system was tested to determine the heat transfer coefficient of ethylene glycol in a DP-type and Coil-type HEs. After that, the heat transfer rate was calculated and compared. The results show that the heat transfer coefficient in the DP-type HE is the lowest at 12.2 W/m2 oC and the highest at 26.8 W/m2 oC; and the corresponding heat transfer rate is the lowest at 8.3 W and the highest is 56.3 W. In comparison, for Coil-type HE, the lowest heat transfer coefficient is 38.9 W/m2 oC and the highest is 66.2 W/m2 oC which correspond to the heat transfer rate 19.9 W at the lowest and 225 W at the highest.

Heat Transfer Enhancement by Turbulent Impinging Jets

2000 ◽  
Author(s):  
M. Kumagai ◽  
R. S. Amano ◽  
M. K. Jensen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Stokes Equations ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Impinging Jets ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

Abstract A numerical and experimental investigation on cooling of a solid surface was performed by studying the behavior of an impinging jet onto a fixed flat target. The local heat transfer coefficient distributions on a plate with a constant heat flux were computationally investigated with a normally impinging axisymmetric jet for nozzle diameter of 4.6mm at H/d = 4 and 10, with the Reynolds numbers of 10,000 and 40,000. The two-dimensional cylindrical Navier-Stokes equations were solved using a two-equation k-ε turbulence model. The finite-volume differencing scheme was used to solve the thermal and flow fields. The predicted heat transfer coefficients were compared with experimental measurements. A universal function based on the wave equation was developed and applied to the heat transfer model to improve calculated local heat transfer coefficients for short nozzle-to-plate distance (H/d = 4). The differences between H/d = 4 and 10 due to the correlation among heat transfer coefficient, kinetic energy and pressure were investigated for the impingement region. Predictions by the present model show good agreement with the experimental data.

Heat Transfer Model in a Rotary Drum During the Fermentation Process

2020 ◽  
Vol 77 (1) ◽  
pp. 151-160
Author(s):  
Norazaliza Mohd Jamil ◽  
Aainaa Izyan Nafsun ◽  
Abdul Rahman Mohd Kasim
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Transfer Coefficient ◽  
Fermentation Process ◽  
Transfer Model ◽  
Kutta Method ◽  
Contact Heat ◽  
Contact Heat Transfer ◽  
Runge Kutta Method ◽  
Rotary Drum

A new mathematical model describing heat transfer during the fermentation process in a rotary drum is proposed. The model includes representations of the kinetic reactions, the temperature of the solid bed, and physical structures within the rotary drum. The model is developed using five ordinary differential equations and was then solved using the Runge-Kutta method embedded in MATLAB software. A reasonable behaviour for the temperature profile to the fermentation process is achieved. The results show that the mass of the solid bed, contact heat transfer coefficient, and the wall temperature has a significant effect on the fermentation process in a rotary drum.

Convective Heat Transfer between Covered Kiln Wall and Material Bed

2013 ◽  
Vol 805-806 ◽  
pp. 492-495 ◽  
Author(s):  
Xiao Yan Yang ◽  
You Gang Xiao ◽  
Xian Ming Lei ◽  
Guo Xin Chen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Transient Heat Conduction ◽  
Transfer Model ◽  
Contact Heat ◽  
Conduction Model ◽  
Contact Heat Transfer

According to kiln structure and material movement features, the transient heat conduction model of material bed and the contact heat transfer model at the interface of covered kiln wall and material bed are built. Considering their contribution to the convective heat transfer of material bed, the convective heat transfer coefficient between covered kiln wall and material bed is proposed, and its formula is obtained, with which the convective heat transfer between covered kiln wall and material bed can be calculated conveniently, so the heat transfer prediction within the rotary kiln can be done more easily.

1D Heat Transfer Model for the Chain Section of a Lime Kiln

2010 ◽  
Author(s):  
Michael Massad ◽  
Samer Hassan ◽  
Masahiro Kawaji ◽  
Honghi N. Tran
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Transfer Model ◽  
Conduction Model ◽  
Chain System ◽  
Lime Kiln ◽  
Lime Mud ◽  
Axial Temperature

This work was aimed at gaining a better understanding of heat transfer within lime kilns, by both experiments and detailed modeling of heat transfer phenomena in the chain section. Experiments were conducted using a laboratory mockup of a rotating kiln to obtain convective heat transfer coefficient data for cooling of a steel rod in dry or wet lime mud. For moisture contents of 0% and 30%, the mud heat transfer coefficient was determined to be 170 and 320 W/m2°C, respectively. A 1-D, unsteady heat conduction model was used to predict the temperature variations of all the chain rings in the chain system and calculate the amount of heat transferred by each chain ring to the lime mud. A thermal model was then developed to predict the steady axial temperature profiles of lime mud, gas and kiln wall throughout a rotating lime kiln equipped with a typical chain system.

Heat Transfer Enhancement in a Horizontal Channel by the Addition of Curved Baffles

2006 ◽  
Author(s):  
J. L. Luviano ◽  
A. Hernandez ◽  
C. Rubio ◽  
D. Banerjee
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Transfer Rate ◽  
Fluid Motion ◽  
Horizontal Channel ◽  
Parallel Plates ◽  
Energy Transfer Rate ◽  
Transfer Enhancement ◽  
The Heat Transfer Coefficient

This paper presents the heat transfer and fluid dynamics analysis of a horizontal channel formed by parallel plates with periodic insertions of heated blocks, having curved deflectors to direct the flow. The heat transfer coefficient investigated is compared with that of the horizontal channel without deflectors. The aim of the deflectors is to lead the fluid to the space between the heated blocks increasing the dynamics in this area. This zone will normally, without deflectors, become a stagnant fluid zone in which low energy transfer rate occurs. The results show that the heat transfer coefficient is larger as compared to that of the case without deflectors. The increment in the heat transfer coefficient is due primarily to the fluid motion stirred in the area between the heated block due to the deflectors. However, it must be pointed out. This implementation also increases the pressure drop in the channel.

An Analytical Model for Bubble Growth and Heat Transfer in Microchannels

2007 ◽  
Author(s):  
Martin Cerza ◽  
Sonia M. F. Garcia ◽  
Joshua L. Nickerson
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Bubble Growth ◽  
Leading Edge ◽  
Superior Performance ◽  
Transfer Model ◽  
Two Phase ◽  
Microchannel Cooling ◽  
Convection Schemes

Forced liquid convection microchannel cooling systems present an alternative to the forced air-convection schemes and offer higher thermal performance. With regard to forced liquid convection, two-phase convection offers superior performance to liquid only convection. This paper presents results developed from a bubble heat transfer growth model applied to microchannel geometry and incorporates these results into a model for the averaged bubble heat transfer coefficient. Results are shown for water and FC-72. The bubble heat transfer model shows that the bubble growth rates and subsequent averaged heat transfer coefficient are functions of the film thickness between the bubble and the microchannel wall, the slip velocity between the bubble and the fluid comprising the bubble base, the wall heat flux and the subsequent liquid superheat in the microchannel just upstream of the bubble leading edge.

scholarly journals Study on the Coupled Heat Transfer Model Based on Groundwater Advection and Axial Heat Conduction for the Double U-Tube Vertical Borehole Heat Exchanger

2020 ◽  
Vol 12 (18) ◽  
pp. 7345
Author(s):  
Linlin Zhang ◽  
Zhonghua Shi ◽  
Tianhao Yuan
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Borehole Heat Exchanger ◽  
Coupled Heat Transfer ◽  
Advection Velocity

In this paper, a dynamic heat transfer model for the vertical double U-tube borehole heat exchanger (BHE) was developed to comprehensively address the coupled heat transfer between the in-tube fluid and the soil with groundwater advection. A new concept of the heat transfer effectiveness was also proposed to evaluate the BHE heat exchange performance together with the index of the heat transfer rate. The moving finite line heat source model was selected for heat transfer outside the borehole and the steady-state model for inside the borehole. The data obtained in an on-site thermal response test were used to validate the physical model of the BHE. Then, the effects of soil type, groundwater advection velocity, inlet water flow rate, and temperature on the outlet water temperature of BHE were explored. Results show that ignoring the effects of groundwater advection in sand gravel may lead to deviation in the heat transfer rate of up to 38.9% of the ground loop design. The groundwater advection fosters the heat transfer of BHE. An increase in advection velocity may also help to shorten the time which takes the surrounding soil to reach a stable temperature. The mass flow rate of the inlet water to the BHE should be more than 0.5 kg·s−1 but should not exceed a certain upper limit under the practical engineering applications with common scale BHE. The efficiency of the heat transfer of the double U-tube BHE was determined jointly by factors such as the soil’s physical properties and the groundwater advection velocity.

Combustion and Heat Transfer in 300MW Oxy-Fired CFBB

2011 ◽  
Vol 354-355 ◽  
pp. 369-375
Author(s):  
Chun Bo Wang ◽  
Xiao Fei Ma ◽  
Jiao Zhang ◽  
Jin Gui Sheng ◽  
Hong Wei Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Particle Diameter ◽  
External Heat ◽  
Transfer Model ◽  
Heat Transfer Characteristics ◽  
Operation Condition ◽  
Transfer Capability ◽  
The Heat Transfer Coefficient

A combustion and heat transfer model in oxy-fired CFBB was set. Particle diameter, voidage of the bed ,etc, was analyzed with 30%, 50%, and 70% oxygen. Take a 300MW CFBB for example, the heat transfer characteristics in furnace were numerical simulated. In the sparse zone, heat transfer coefficient is proportional to oxygen concentration at the same voidage of the bed; under the same operation condition, the heat transfer coefficient in CFB increases with the voidage of the bed at first, then it decreases. It was found the heat transfer capability decrease due to the higher concentration of oxygen. It is necessary to set an external heat exchanger to keep a normal combustion

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