Therapeutic Equipment for Brain-Hyperthermia Using Convective Spray Cooling

2017 ◽  
Vol 11 (3) ◽  
Author(s):  
Imran Mahmood ◽  
Ali Raza
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Image Analysis ◽  
Heat Exchanger ◽  
Emergency Treatment ◽  
Spray Cooling ◽  
The Body ◽  
New Type ◽  
Thermoregulatory System ◽  
Brain Hyperthermia

A new type of therapeutic equipment is designed herein, using concepts of convective heat transfer and spray cooling, to treat patients suffering from brain-hyperthermia. The equipment is aimed to provide emergency treatment in order to prevent disability or possible mortality because thermoregulatory system of the patients fails to maintain a homeostasis. The equipment uses noncontact method of forced convection, applied uniformly at body exteriors. The heat exchanger is designed to contain four independent pipe-sections with orifice openings around the body. The cool-air, maintained within ASHRAE’s thermal comfort bounds, is sprayed through the orifices. Design improvements have been made on the basis of image analysis of the flow. The boundary layer (BL) analysis has also been performed over a specially designed mannequin with induced hyperthermia characteristics. The testing indicates a decay of ∼6 °C in 280 min with a time constant of 2 h. Comparative to existing techniques, in addition to being a noncontact approach, the equipment shows better thermoregulatory performance along with a flexibility to accommodate different body contours.

A Proposed Method for Determining the Heat Transfer Properties of Foam-Fins

2006 ◽  
Author(s):  
Robert J. Moffat ◽  
John K. Eaton ◽  
Andrew Onstad
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Experimental Testing ◽  
Solid Material ◽  
Heated Wall ◽  
Optimized Design ◽  
Present Sample ◽  
Compact Heat Exchangers ◽  
Heat Exchanger Design ◽  
New Type

Metallic and graphitic open-cell foams are being used as extended surfaces in some designs of compact heat exchangers. The shape and orientation of the solid material in the foam is hard to describe in classical terms and harder still to model. There appears to be a clear need for a method of characterizing foams that allows flexible, optimized design of a foam-fin heat exchanger. To be most useful, the description should be expressed in terms that are consistent with current heat exchanger design methods. The heat transfer performance of a foam-fin can be calculated if three parameters are known: the product hmAc* (the convective conductance per unit volume) as a function of flow rate, the product ksAk* (the effective conductive conductance as a fin), and Rbond, the effective thermal resistance between the foam fin and the surface to which it is attached. An experimental method is presented by which these three properties can be determined using the results from two tests: a conventional heat exchanger core test (single-blow-transient or cyclic) to measure hmAc* and a new type of "one-heated-wall" test, described here, from which the temperature distribution in the foam can be inferred. Results from these two tests can be combined to evaluate the three necessary parameters: hmAc*, ksAk* and Rbond. In this paper we describe the theory behind this approach and present sample calculations showing the type of data that are expected and demonstrating that the necessary parameters can be measured with these tests. Experimental testing of the method is underway but has not yet been completed, hence no data are available at this time to confirm the validity or practicality of the method.

The Variation in Effectiveness of Low-Finned Tubes Within a Shell-and-Tube Heat Exchanger for Supercritical CO2

2012 ◽  
Author(s):  
Patrick M. Fourspring ◽  
Joseph P. Nehrbauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Exchanger ◽  
Thermal Conductance ◽  
Heat Transfer Area ◽  
Shell Side ◽  
Additional Heat ◽  
Tube Heat Exchanger ◽  
Finned Tubes ◽  
Shell And Tube

Low-finned tubes can be effective in baffled flow heat exchangers, if the heat transfer coefficients on either side of the heat exchanger differ greatly and therefore limit the thermal conductance of the heat exchanger. Low-finned tubes can increase thermal conductance by providing additional heat transfer area on the limiting side. The height and the spacing of the low-fins must be greater than the thickness of the thermal boundary layer on the low-finned side of the heat exchanger. Otherwise, the effectiveness of the additional area that the low-finned tubes provide will be reduced. The boundary layer thickness is dependent on the velocity and the thermophysical properties of the fluids. Therefore, in a standard shell-and-tube heat exchanger, the number of heat exchanger shell-side baffles needs to be properly considered to provide the correct shellside velocity without introducing too much pressure drop. Testing of a shell-and-tube heat exchanger containing low-finned tubes varied the flow rate and pressure of the supercritical CO2 on the shell side as water provided the cooling on the tube side. The testing maintained the temperature and pressure of the CO2 above the critical point in order to determine the changes in the effectiveness of the low-finned tubes and thus the heat transfer rate of the heat exchanger. The results show that the additional heat transfer area provided by the low-finned tubes will remain fully effective, even as the supercritical fluid nears its critical point or a pseudo-critical temperature. This result also supports (but is not sufficient to prove) the guidance to limit the estimated thickness of the thermal boundary layer to the fin height and twice the fin spacing to ensure the additional heat transfer area provided by the low-finned tubes remain effective.

Flow and Heat Transfer From the Annular Fin Heat Exchanger Using Winglet Type Vortex Generators

2013 ◽  
Author(s):  
Basanta Kumar Rana ◽  
Amaresh Dalal ◽  
Gautam Biswas
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Exchanger ◽  
Thermal Boundary Layer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Vortex Generators ◽  
Flow And Heat Transfer ◽  
Finned Tube Heat Exchanger ◽  
Annular Fin

A numerical study of three-dimensional flow and heat transfer from the annular finned tube heat exchanger with built-in delta winglets is carried out. The delta winglets type vortex generators which are placed on the annular fin surface in the neighborhood of the cylinder are used to enhance the heat transfer. The winglets are placed in common flow orientation. Longitudinal vortices develop along the side edge of the delta winglets due to the pressure difference between the front surface (facing the flow) and back surface. These vortices interact with thermal boundary layer and produce a three dimensional swirling flow that mixes near wall fluid with the midstream. Thus the thermal boundary layer is disrupted and heat transfer is enhanced. The investigations are carried out for four different Reynolds number (100, 500 and 1000) and four different angles of attack (35°, 40°, 45°, 50°) for common flow up (CFU) configuration. It is found that heat transfer increases about 11% for Re = 1000 with angle of attack 40°.

scholarly journals Active control of flow and heat transfer in boundary layer on the porous body of arbitrary shape

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 295-309
Author(s):  
Dragisa Nikodijevic ◽  
Zivojin Stamenkovic ◽  
Dragan Zivkovic ◽  
Aleksandar Boricic ◽  
Milos Kocic
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Active Control ◽  
Porous Body ◽  
Arbitrary Shape ◽  
The Body ◽  
Unsteady Temperature ◽  
Approximation Characteristic ◽  
Flow And Heat Transfer ◽  
Control Of Flow

The paper discusses the possibility of active control of flow and heat transfer using a magnetic field and suction in a generalized form. The unsteady temperature two-dimensional laminar magnetohydrodynamic boundary layer of incompressible fluid on a porous body of arbitrary shape is analyzed. Outer electric filed is neglected, magnetic Reynolds number is significantly lower than one i. e. the considered problem is in inductionless approximation. Characteristic properties of fluid are constant and it is assumed that a uniform suction or injection of a fluid, same as the fluid in primary flow, can take place through the body surface. The boundary-layer equations are generalized such that the equations and the boundary conditions are independent of the particular conditions of the problem, and this form is considered as universal. Obtained universal equations are numerically solved using the ?progonka? method. Numerical results for the dimensionless velocity, temperature, shear stress and heat transfer as functions of introduced sets of parameters are obtained, displayed graphically and used to carry out general conclusions about the development of temperature magnetohydrodynamic boundary layer.

Ultra-Cooling Heat Transfer Characteristics Using Cryogenic Micro-Solid Nitrogen Spray

2012 ◽  
Author(s):  
U. Oh ◽  
Jun Ishimoto ◽  
Naoki Harada ◽  
Daisuke Tan
Keyword(s):  
Heat Transfer ◽  
Heated Surface ◽  
Spray Cooling ◽  
High Heat ◽  
Heat Transfer Process ◽  
Solid Particles ◽  
High Heat Flux ◽  
Heat Transfer Characteristics ◽  
Solid Nitrogen ◽  
New Type

The fundamental characteristics of heat transfer and cooling performance of micro-solid nitrogen particulate spray impinging on a heated substrate were numerically investigated and experimentally measured by a new type of integrated computational-experimental technique. The employed CFD based on the Euler-Lagrange model is focused on the cryogenic spray behavior of atomized particulate micro-solid nitrogen and also on its ultra-high heat flux cooling characteristics. Based on the numerically predicted performance, a new type of cryogenic spray cooling technique for application to a ultra-high heat power density device was developed. In the present integrated computation, it is clarified that the cryogenic micro-solid spray cooling characteristics are affected by several factors of the heat transfer process of micro-solid spray which impinges on heated surface as well as by atomization behavior of micro-solid particles.

scholarly journals Cyclical reverse thermosiphon

2010 ◽  
Vol 31 (1) ◽  
pp. 3-32 ◽  
Author(s):  
Yuriy Dobriansky ◽  
Yigzaw Yohanis
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Experimental Methods ◽  
Local Heat ◽  
Flow Loop ◽  
Liquid Circulation ◽  
Saturated Vapour ◽  
New Type ◽  
Liquid Heat ◽  
Direction Opposite

Cyclical reverse thermosiphonWe describe the development of a new type of heat exchanger. This heat exchanger operates using reverse thermosiphon action and consists of a self-acting and self-controlled liquid circulation loop with heat transfer in a downward direction, opposite to the direction of natural convection. This process moves a heat-carrying hot liquid downwards with the help of local heat transferred through the loop. This flow loop is partly filled with liquid and the upper part of the loop contains vapour from the liquid heat-carrier. The pressure difference in the saturated vapour is used to move the heated liquid downwards. The principles of action and the possibility of developing such a device using laboratory experimental methods are presented.

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