Using Thermoelectric Cooling With Tourniquets for Nerve Preservation

2016 ◽  
Author(s):  
M. Trupiano ◽  
S. Aarabi ◽  
A. F. Emery
Keyword(s):  
Thermal Conditions ◽  
Ambient Conditions ◽  
Transfer Coefficients ◽  
Thermoelectric Coolers ◽  
Ambient Temperatures ◽  
Nerve Preservation ◽  
Heat Transfer Coefficients ◽  
Surface Temperatures ◽  
Element Simulation ◽  
Free And Forced Convection

The use of a tourniquet leads to nerve damage, even if applied for short periods of time. This damage can be minimized if the limb is cooled. Because of the low conductivities of human tissue, core limb cooling is slow unless the surface temperature is very cool. Subzero surface temperatures can lead to skin injury (i.e., frostbite). Ideally one would adjust the limb surface temperatures as a function of time to maximize the cooling rate while avoiding permanent tissue damage. One possible approach is to use a thermoelectric cooler (TEC) in conjunction with a programmable power supply. TEC performance varies strongly with heat absorption rate, a function of limb thermal properties, and hot side temperatures that are strongly affected by the surface conditions on the hot side, i.e., overall heat transfer coefficients and ambient conditions. The paper describes the use of finite element simulation to predict the usefulness of using thermoelectric coolers applied to the surface of a limb when compared to the standard approach of using ice packs. Since the TEC performance is strongly influenced by its warm side thermal conditions, experimental results are presented for different ambient temperatures, free and forced convection, and evaporation of water from a wickable covering.

Heat Transfer Measurements Using Multiple Thermochromic Liquid Crystals in Symmetric Cooling Channels

2020 ◽  
Author(s):  
Tobias Krille ◽  
Stefan Retzko ◽  
Rico Poser ◽  
Jens von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Single Channels ◽  
Ambient Conditions ◽  
Transfer Coefficients ◽  
Experimental Conditions ◽  
Cooling Channels ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer

Abstract The transient Thermochromic Liquid Crystal (TLC) method is applied to determine the distribution of the local heat transfer coefficients using a configuration with parallel cooling channels at an engine relevant Reynolds number. The rectangular channels with a moderate aspect ratio and a high length-to-diameter ratio are equipped with one-sided oblique ribs with high blockage, which is a promising configuration for turbine near wall cooling applications. In this arrangement, the three inner channels should experience same flow and thermal conditions. Numerical simulations are performed to substantiate this assumption. The symmetric single channels are sprayed with narrowband TLC with various indication temperatures. Multiple experiments were conducted. All start at ambient conditions before the fluid is heated up to several temperatures between 46°C and 73°C. The results show that the determined local heat transfer coefficients and therefore the Nusselt numbers vary significantly for the different experimental conditions especially at locations of high heat transfer coefficient behind the ribs. A simplified procedure with respect to measurement uncertainties is applied to enable an easy and fast valuation on the data quality. This might be used within the data reduction analysis for such experiments directly. The approach is illustrated using the obtained experimental data.

Preliminary studies of the loss of heat from leaves under conditions of free and forced convection

1965 ◽  
Vol 13 (2) ◽  
pp. 153 ◽  
Author(s):  
GI Pearman
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Wind Tunnel ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Free And Forced Convection ◽  
Wind Velocities ◽  
The Heat Transfer Coefficient

An account is given of techniques and methods used in measurement of convective heat transfer from leaves of the succulent Carpobrotus. Heat transfer was studied under still air conditions and in wind (in a specially constructed wind-tunnel) up to velocities of 300 cm sec-1. A correlation was demonstrated between experimentally obtained values of heat transfer coefficients and theoretical values calculated from empirical formulae. At wind velocities of 300 cm sec-1 the heat transfer coefficient for Carpobrotus was increased to seven times its value still air.

scholarly journals Thermal modes simulation of cooling panels in waste water pumping stations

Vestnik MGSU ◽  
2021 ◽  
pp. 1378-1387
Author(s):  
Vitaly I. Prohorov ◽  
Muhammet A. Razakov
Keyword(s):  
Waste Water ◽  
Heat Transfer ◽  
Mathematical Model ◽  
Thermal Conditions ◽  
Engineering Calculation ◽  
Transfer Coefficients ◽  
Pumping Station ◽  
Heat Transfer Coefficients ◽  
Water Pumping ◽  
Functional Areas

Introduction. Authors considers a new method of cooling some functional areas in a city sewage pumping station. They have used the works of Isachenko V.A., Osipov V.A., Sukomel A.S., Bogoslovsky V.N. to simulate the PLI panel’s stationary thermal regime. Materials and methods. Authors have considered the mathematical modeling of stationary and non-stationary thermal phenomena in the PLI panel in this paper. There are the possibilities of modeling the thermal modes of the panel PLI which depending on the place of installation of this device. Authors have given the theoretical characteristics of the heated air in this device and some results of survey in a high voltage urban waste water pumping station in Moscow. There are the heat inputs and heat losses calculations of PLI panel’s various structural elements which carried out using the theory of similarity in this article. Researchers considered the possibility of use other empirical results to determine some of the coefficients which involved in modeling. It has been presented different heat transfer coefficients which could be used in thermal conditions model of PLI panel. There are the validation of the developed models which proved by comparing the deviations in the heat balance equation of the PLI panel. Results. Authors has developed a physical and mathematical model of PLI panel’s thermal modes for a sewage pimping station. Authors have given the recommendations on the possibility of using the different heat transfer coefficients in PLI panel’s thermal conditions modeling process. A numerical experiment was carried out to simulate one PLI panel under the conditions of a sewage pumping station by researchers in this paper. Conclusions. According to the information, this physical and mathematical model can be used for engineering calculation when engineer is selecting the characteristics of PLI panel and also it could be used to clarifying the distributions of heat flow from PLI panel.

An Experimental Investigation of Convective Heat Transfer at the Leading Edge of a Gas Turbine Airfoil

1992 ◽  
Author(s):  
S. Gendron ◽  
N. J. Marchand ◽  
C. Korn ◽  
J. P. Immarigeon ◽  
J. J. Kacprzynski
Keyword(s):  
Heat Transfer ◽  
Leading Edge ◽  
Temperature Measurements ◽  
Transfer Coefficients ◽  
Testing Conditions ◽  
Heat Transfer Coefficients ◽  
Hot Gas ◽  
Surface Temperatures ◽  
Double Edge

This paper describes the experimental methods used to determine the surface temperatures and heat-transfer coefficients at the leading edge, and elsewhere over the surface, of a specially designed double-edge wedge shell specimen subjected to cyclic heating in a high velocity hot gas stream generated by a burner rig. The methods included temperature measurements with thermocouples (embedded below the surface) as well as surface temperature measurements by optical pyrometry. The experiments were carried-out at gas temperatures between 806 to 1323 °C and velocities in the range from Mach 0.32 to Mach 0.39. The calibration procedures for each method, the various testing conditions to which the airfoil-like specimen was exposed and the results pertaining to the determination of the surface temperatures and heat-transfer coefficients are described and discussed.

Laminar Transport Phenomena in parallel Channels with a Short Flow Construction

1979 ◽  
Vol 101 (2) ◽  
pp. 217-221 ◽  
Author(s):  
S. Bunditkul ◽  
Wen-Jei Yang
Keyword(s):  
Transport Phenomena ◽  
Numerical Procedure ◽  
Thermal Conditions ◽  
Transfer Coefficients ◽  
Fully Developed Flow ◽  
Heat Transfer Coefficients ◽  
Flow Geometry ◽  
Parallel Channels ◽  
Fanning Friction Factor ◽  
Hydrodynamic Effects

A finite-difference numerical analysis was conducted in [3] to investigate laminar transport phenomena in constricted parallel ducts with fully developed flow and temperature profiles. The same numerical procedure is employed to determine laminar transfer phenomena in parallel channels with a short flow constriction within which the flow is still developing. Two limiting thermal conditions are treated: uniform surface temperature and uniform surface heat flux. Theoretical results are obtained for the pressure, streamline, velocity and temperature distributions, the loss coefficients, the Fanning friction factor, and the local and average heat transfer coefficients. Two new dimensionless parameters are derived which describe the transfer performance in the ducts with a short flow constriction. Both the hydrodynamic and thermo-hydrodynamic effects at the entrance as well as the exit of the constricted flow geometry are determined. The numerical scheme is capable of treating high velocity flows up to the transition Reynolds number.

An Experimental Investigation of a Low Heat Flux, Wickless Heat Pipe

1983 ◽  
Vol 7 (2) ◽  
pp. 96-99
Author(s):  
B.S. Larkin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Pipe ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Electronic Package ◽  
Ambient Temperatures ◽  
Heat Transfer Coefficients ◽  
Flux Charge

This paper reports tests on a wickless heat pipe to be used for transporting heat from the ground to protect an electronic package from low ambient temperatures. Evaporating heat transfer coefficients were measured for low heat fluxes where the behaviour of the evaporating film is unpredictable. The effects of type of working fluid, heat flux, charge quantity and tube inclination were investigated.

scholarly journals Effects of Albedo and Thermal Inertia on Pavement Surface Temperatures with Convective Boundary Conditions—A CFD Study

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2078
Author(s):  
Tathagata Acharya ◽  
Brooke Riehl ◽  
Alan Fuchs
Keyword(s):  
Building Materials ◽  
Thermal Inertia ◽  
Concrete Surface ◽  
Published Data ◽  
Concrete Pavements ◽  
Ambient Conditions ◽  
Convective Boundary ◽  
Ambient Temperatures ◽  
Pavement Surface ◽  
Surface Temperatures

The urban heat island (UHI) effect increases the ambient temperatures in cities and alters the energy budget of building materials. Urban surfaces such as pavements and roofs absorb solar heat and re-emit it back into the atmosphere, contributing towards the UHI effect. Over the past few decades, researchers have identified albedo and thermal inertia as two of the most significant thermal properties that influence pavement surface temperatures under a given solar load. However, published data for comparisons of albedo and thermal inertia are currently inadequate. This work focuses on asphalt and concrete as two important materials used in the construction of pavements. Computational fluid dynamics (CFD) analyses are performed on asphalt and concrete pavements with the same dimensions and under the same ambient conditions. Under given conditions, the pavement top surface temperature is evaluated with varying albedo and thermal inertia values. The results show that the asphalt surface temperatures are consistently higher than the concrete surface temperatures. Surface temperatures under solar load reduce with increasing albedo and thermal inertia values for both asphalt and concrete pavements. The CFD results show that increasing the albedo is more effective in reducing pavement surface temperatures than increasing the thermal inertia.

3D Compact Model of Packaged Thermoelectric Coolers

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Owen Sullivan ◽  
Borislav Alexandrov ◽  
Saibal Mukhopadhyay ◽  
Satish Kumar
Keyword(s):  
Steady State ◽  
Finite Volume ◽  
Thermal Contact ◽  
Transient Behavior ◽  
Compact Model ◽  
Transfer Coefficients ◽  
Thermoelectric Coolers ◽  
Electronic Package ◽  
Heat Transfer Coefficients ◽  
A Tec

Hotspots on a microelectronic package can severely hurt the performance and long-term reliability of the chip. Thermoelectric coolers (TECs) can provide site-specific and on-demand cooling of hot spots in microprocessors. We develop a 3D compact model for fast and accurate modeling of a TEC device integrated inside an electronic package. A 1D compact model of a TEC is first built in SPICE and validated for steady-state and transient behavior against a finite-volume model. The 1D compact model of the TEC is then incorporated into a 3D compact model of a prototype electronic package. The results from the compact model for the packaged TEC are in good agreement with a finite-volume based model, which confirms the compact model's ability to accurately model the TEC's interaction with the package. Analysis of packaged TECs using this 3D compact model shows that (i) moving TECs closer to the chip results in faster response time and an increase in maximum cooling, (ii) high thermal contact resistance within the thermoelectric cooler significantly degrades performance of the device, and (iii) higher convective heat transfer coefficients (HTC) at the heat spreader surface increase steady-state cooling but decrease maximum transient cooling.

scholarly journals Heat Transfer Measurements Using Multiple Thermochromic Liquid Crystals in Symmetric Cooling Channels

2021 ◽  
pp. 1-22
Author(s):  
Tobias Krille ◽  
Stefan Retzko ◽  
Rico Poser ◽  
Jens Von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Single Channels ◽  
Ambient Conditions ◽  
Transfer Coefficients ◽  
Experimental Conditions ◽  
Cooling Channels ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer

Abstract The transient Thermochromic Liquid Crystal (TLC) method is applied to determine the distribution of the local heat transfer coefficients using a configuration with parallel cooling channels at an engine relevant Reynolds number. The rectangular channels with a moderate aspect ratio and a high length-to-diameter ratio are equipped with one-sided oblique ribs with high blockage, which is a promising configuration for turbine near wall cooling applications. In this arrangement, the three inner channels should experience same flow and thermal conditions. Numerical simulations are performed to substantiate this assumption. The symmetric single channels are sprayed with narrowband TLC with various indication temperatures. Multiple experiments were conducted. All start at ambient conditions before the fluid is heated up to several temperatures between 46°C and 73°C. The results show that the determined local heat transfer coefficients and therefore the Nusselt numbers vary significantly for the different experimental conditions especially at locations of high heat transfer coefficient behind the ribs. A simplified procedure with respect to measurement uncertainties is applied to enable an easy and fast valuation on the data quality. This might be used within the data reduction analysis for such experiments directly. The approach is illustrated using the obtained experimental data.

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