Active Thermal Control of an Ion-Drag Pump Assisted Micro Heat Pipe

2000 ◽  
Author(s):  
Zhiquan Yu ◽  
Nicholas A. Pohlman ◽  
Kevin P. Hallinan ◽  
Reza Kashani
Keyword(s):  
Electric Field ◽  
Heat Transport ◽  
Analytical Model ◽  
Temperature Control ◽  
Fold Increase ◽  
Thermal Control ◽  
Transport Capacity ◽  
Maximum Heat ◽  
Micro Heat Pipes ◽  
Active Temperature

Abstract An ion-drag pump is utilized to enhance the heat transport capacity of micro heat pipes. An analytical model is developed to estimate the maximum heat transport capacity as a function of the applied electric field. The model predicts that the application of an electric field causes a four fold increase in heat transport capacity. A transient analytical model was developed to permit variation of the electric field with applied thermal load. A proportional-integral-derivative controller was used to simulate active temperature control. The feasibility of achieving active temperature control was demonstrated experimentally.

The Heat Transport Capacity of Micro Heat Pipes

1998 ◽  
Vol 120 (4) ◽  
pp. 1064-1071 ◽  
Author(s):  
J. M. Ha ◽  
G. P. Peterson
Keyword(s):  
Experimental Data ◽  
Heat Pipe ◽  
Heat Transport ◽  
Heat Pipes ◽  
Original Model ◽  
Semiempirical Model ◽  
Transport Capacity ◽  
Predictive Tool ◽  
Maximum Heat ◽  
Micro Heat Pipes

The original analytical model for predicting the maximum heat transport capacity in micro heat pipes, as developed by Cotter, has been re-evaluated in light of the currently available experimental data. As is the case for most models, the original model assumed a fixed evaporator region and while it yields trends that are consistent with the experimental results, it significantly overpredicts the maximum heat transport capacity. In an effort to provide a more accurate predictive tool, a semi-empirical correlation has been developed. This modified model incorporates the effects of the temporal intrusion of the evaporating region into the adiabatic section of the heat pipe, which occurs as the heat pipe approaches dryout conditions. In so doing, the current model provides a more realistic picture of the actual physical situation. In addition to incorporating these effects, Cotter’s original expression for the liquid flow shape factor has been modified. These modifications are then incorporated into the original model and the results compared with the available experimental data. The results of this comparison indicate that the new semiempirical model significantly improves the correlation between the experimental and predicted results and more accurately represents the actual physical behavior of these devices.

Theoretical Analysis of the Maximum Heat Transport in Triangular Grooves: A Study of Idealized Micro Heat Pipes

1996 ◽  
Vol 118 (3) ◽  
pp. 731-739 ◽  
Author(s):  
G. P. Peterson ◽  
H. B. Ma
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Control Volume ◽  
Flow Characteristics ◽  
Heat Pipes ◽  
Vapor Flow ◽  
Transport Capacity ◽  
Maximum Heat ◽  
Micro Heat Pipes ◽  
Theoretical Minimum

A mathematical model for predicting the minimum meniscus radius and the maximum heat transport in triangular grooves is presented. In this model, a method for determining the theoretical minimum meniscus radius was developed and used to calculate the capillary heat transport limit based on the physical characteristics and geometry of the capillary grooves. A control volume technique was employed to determine the flow characteristics of the micro heat pipe, in an effort to incorporate the size and shape of the grooves and the effects of the frictional liquid–vapor interaction. In order to compare the heat transport and flow characteristics, a hydraulic diameter, which incorporated these effects, was defined and the resulting model was solved numerically. The results indicate that the heat transport capacity of micro heat pipes is strongly dependent on the apex channel angle of the liquid arteries, the contact angle of the liquid flow, the length of the heat pipe, the vapor flow velocity and characteristics, and the tilt angle. The analysis presented here provides a mechanism whereby the groove geometry can be optimized with respect to these parameters in order to obtain the maximum heat transport capacity for micro heat pipes utilizing axial grooves as the capillary structure.

Experimental Investigation of the Maximum Heat Transport in Triangular Grooves

1996 ◽  
Vol 118 (3) ◽  
pp. 740-746 ◽  
Author(s):  
H. B. Ma ◽  
G. P. Peterson
Keyword(s):  
Experimental Investigation ◽  
Heat Transport ◽  
Heat Pipes ◽  
Effective Area ◽  
Experimental Results ◽  
Test Facility ◽  
Working Fluid ◽  
Maximum Heat ◽  
Pressure Losses ◽  
Micro Heat Pipes

An experimental investigation was conducted and a test facility constructed to measure the capillary heat transport limit in small triangular grooves, similar to those used in micro heat pipes. Using methanol as the working fluid, the maximum heat transport and unit effective area heat transport were experimentally determined for ten grooved plates with varying groove widths, but identical apex angles. The experimental results indicate that there exists an optimum groove configuration, which maximizes the capillary pumping capacity while minimizing the combined effects of the capillary pumping pressure and the liquid viscous pressure losses. When compared with a previously developed analytical model, the experimental results indicate that the model can be used accurately to predict the heat transport capacity and maximum unit area heat transport when given the physical characteristics of the working fluid and the groove geometry, provided the proper heat flux distribution is known. The results of this investigation will assist in the development of micro heat pipes capable of operating at increased power levels with greater reliability.

Investigation of a Novel Flat Heat Pipe

2005 ◽  
Vol 127 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Yaxiong Wang ◽  
G. P. Peterson
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Thermal Design ◽  
Experimental Results ◽  
Design Parameters ◽  
Working Fluid ◽  
Transport Capacity ◽  
Maximum Heat ◽  
Mesh Screen ◽  
Flat Heat Pipe

A novel flat heat pipe has been developed to assist in meeting the high thermal design requirements in high power microelectronics, power converting systems, laptop computers and spacecraft thermal control systems. Two different prototypes, each measuring 152.4 mm by 25.4 mm were constructed and evaluated experimentally. Sintered copper screen mesh was used as the primary wicking structure, in conjunction with a series of parallel wires, which formed liquid arteries. Water was selected as the working fluid. Both experimental and analytical investigations were conducted to examine the maximum heat transport capacity and optimize the design parameters of this particular design. The experimental results indicated that the maximum heat transport capacity and heat flux for Prototype 1, which utilized four layers of 100 mesh screen were 112 W and 17.4W/cm2, respectively, in the horizontal position. For Prototype 2, which utilized six layers of 150 mesh screen, these values were 123 W and 19.1W/cm2, respectively. The experimental results were in good agreement with the theoretical predictions for a mesh compact coefficient of C=1.15.

Experimental Investigation of Micro Heat Pipe Radiators in Radiation Environment

2001 ◽  
Author(s):  
Y. X. Wang ◽  
G. P. Peterson
Keyword(s):  
Experimental Investigation ◽  
Heat Pipe ◽  
Heat Transport ◽  
Radiation Efficiency ◽  
Wire Diameter ◽  
Radiation Environment ◽  
Transport Capacity ◽  
Maximum Heat ◽  
Micro Heat Pipe

Abstract A flexible micro heat pipe radiator, fabricated by sintering an array of aluminum wires between two thin aluminum sheets, was developed as part of a program to conceptulize, develop, and test lightweight, flexible radiator fin structures for use on long-term spacecraft missions. A detailed experimental investigation was conducted to determine the temperature distribution, maximum heat transport capacity, and radiation efficiency of these micro heat pipe radiators in a radiation environment. Experimental results from three Aluminum-Acetone micro heat pipe radiators with wire diameters of 0.635 mm, 0.813 and 1.016 mm are presented, evaluated and discussed. The results of the experimental program indicted that the maximum heat transport capacity and radiation efficiency, both increased with increasing wire diameter. The maximum heat transport capacity of the micro heat pipe radiator utilizing a wire diameter of 0.635 mm was 15.2 W. The radiators utilizing wire diameters of 0.813 mm and 1.016 mm never reached the maximum heat transport capacities for the given test conditions. In the tests, temperature distributions were recorded for several sink temperatures and indicated that as the sink temperature decreased the radiation efficiency decreased for a given heat input. The maximum heat transport capacity increased with increasing evaporating temperature for the micro heat pipe radiator utilizing a wire diameter of 0.635 mm. Comparison of micro heat pipe radiators with and without working fluid, indicated that significant improvements in temperature uniformity and radiation efficiencies could be obtained, especially at high heat fluxes. A maximum radiation efficiency of 0.95 was observed. In general, while some variation in performance was observed, all three micro heat pipe radiators were found to be capable of meeting the thermal requirements of long-term missions.

Experimental Study of a Two-Phase Heat Transport Device Driven by Electrohydrodynamic Conduction Pumping

2008 ◽  
Author(s):  
Matthew R. Pearson ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Experimental Study ◽  
Electric Field ◽  
Capillary Pressure ◽  
Heat Transport ◽  
Working Fluid ◽  
Transport Capacity ◽  
Two Phase ◽  
Macro Scale ◽  
Transport Device ◽  
Capillary Phenomenon

Heat pipes are well-known as simple and effective heat transport devices, utilizing two-phase flow and the capillary phenomenon to remove heat. However, the generation of capillary pressure requires a wicking structure and the overall heat transport capacity of the heat pipe is generally limited by the amount of capillary pressure generation that the wicking structure can achieve. Therefore, to increase the heat transport capacity, the capillary phenomenon must be either augmented or replaced by some other pumping technique. Electro-hydrodynamic (EHD) conduction pumping has been demonstrated as an effective method for pumping liquid films by using DC electric fields and a dielectric working fluid. Beyond increased pumping capacity, EHD conduction pumping offers other advantages over capillary pumping, such as active control of the pumping capacity via the intensity of the applied electric field. This experimental study demonstrates the prospects of a macro-scale two-phase heat transport device that is driven by EHD conduction pumping. Various liquid film thicknesses are considered. In each case, the performance of the EHD-driven heat transport device at various electric field intensities is compared to the capabilities of the same device under gravity alone. The effect of tilt on the device is also considered.

scholarly journals ТЕПЛОТРАНСПОРТНАЯ СПОСОБНОСТЬ ФИТИЛЯ ИЗ МЕТАЛЛИЧЕСКИХ СЕТОК

2020 ◽  
pp. 27-33
Author(s):  
Геннадий Александрович Горбенко ◽  
Рустем Юсуфович Турна ◽  
Роман Сергеевич Орлов ◽  
Евгений Эдуардович Роговой
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Thermal Transport ◽  
Porous Structures ◽  
Transport Capacity ◽  
Metal Mesh ◽  
Maximum Heat ◽  
Low Weight ◽  
Microgravity Conditions ◽  
Metal Meshes

In the manufacture of wicks for capillary transport of coolant in various heat transfer devices such as heat pipes, capillary pumped loop, accumulators with thermal regulation, evaporative heat exchangers, heat sinks, etc., capillary porous structures are used. Capillary and porous structures made of compressed powders (metal or non-metal) are widely used. However, the technology of making such porous structures is complicated and time-consuming. Important requirements for wicks are high capillary pressure, low-pressure drop, low weight, and manufacturability.  Capillary porous structure, which meets these requirements, can be a wick made of several layers of metal mesh, superimposed on each other, and connected by contact welding. The main advantages of such wicks are low weight and ease of fabrication. The article deals with the methods and results of determining the limit heat transfer capacity of a free wick (not in contact with solid walls) of metal meshes. The design of an experimental unit is given, which allows testing not only at positive but also at small negative angles of the wick to the horizon. Experiments on ammonia to determine the limit heat transport capacity of a flat free wick made of two-layer metal mesh 0.2×0.13 mm woven weave is conducted. By results of the spent experiments dependence of limiting the heat-transport ability of a wick from the temperature of saturation of the heat carrier and an angle of slope to the horizon is received. The performed experiments allow for a wick of the given design to calculate its maximum heat-transport capacity in earth conditions at any width, a transport length of a wick, and an angle of slope to the horizon. Formulas for calculating the thermal transport capacity of wicks made of metal mesh of different length and width under microgravity conditions and in the field of gravity of the earth at different orientations are recommended. The results of the experiments allow determining the thermal transport capacity of wicks from metal meshes and in microgravity conditions.

Thermal analysis of Al2O3/water nanofluid-filled micro heat pipes

RSC Advances ◽  
2015 ◽  
Vol 5 (34) ◽  
pp. 26716-26725 ◽  
Author(s):  
Jie Sheng Gan ◽  
Yew Mun Hung
Keyword(s):  
Thermal Analysis ◽  
Thermal Resistance ◽  
Heat Transport ◽  
Performance Indicators ◽  
Heat Pipes ◽  
Physical Significance ◽  
Transport Capacity ◽  
Micro Heat Pipes

The comparison of heat transport capacity and the thermal resistance as the performance indicators provides valuable insights into the underlying physical significance of the use of a nanofluid on the performance of micro heat pipes.

Sign in / Sign up

Export Citation Format

Share Document