A Heat Plate Leading Edge for Hypersonic Vehicles

2008 ◽  
Author(s):  
Scott D. Kasen ◽  
Doug T. Queheillalt ◽  
Craig A. Steeves ◽  
Anthony G. Evans ◽  
Haydn N. G. Wadley
Keyword(s):  
Heat Flux ◽  
Low Temperature ◽  
Heat Pipe ◽  
Thermal Management ◽  
Leading Edge ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Hypersonic Vehicles ◽  
Vapor Flow ◽  
Leading Edges

The intense thermal flux at the leading edges of hypersonic vehicles (traveling at Mach 5 and greater) requires creative thermal management strategies to prevent damage to leading edge components. Carbon fiber composites and/or ablative coatings have been widely utilized to mitigate the effects of the impinging heat flux. This paper focuses on an alternative, metallic leading edge heat pipe concept which combines efficient structural load support and thermal management. The passive concept is based on high thermal conductance heat pipes which redistribute the high heat flux at the leading edge stagnation point through the evaporation, vapor flow, and condensation of a working fluid to a location far from the heat source. Structural efficiency is provided by a sandwich construction using an open-cell core that also allows for vapor flow. A low temperature proof-of-concept copper–water system has been investigated by experimentation. Measuring of the axial temperature profile indicates effective spreading of thermal energy, a lowering of the maximum temperature and reduced overall thermal gradient compared to a non-heat pipe leading edge. A simple transient analytical model based on lumped thermal capacitance theory is compared with the experimental results. The low-temperature prototype shows potential for higher temperature metallic leading edges that can withstand the hypersonic thermo-mechanical environment.

Heat Pipe Thermal Management at Hypersonic Vehicle Leading Edges: A Low-Temperature Model Study

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Scott D. Kasen ◽  
Haydn N. G. Wadley
Keyword(s):  
Low Temperature ◽  
Heat Pipe ◽  
Thermal Management ◽  
Thermal Flux ◽  
Management Strategies ◽  
Water System ◽  
Leading Edge ◽  
Working Fluid ◽  
Two Phase ◽  
Leading Edges

The intense thermal fluxes and aero-thermomechanical loads generated at sharp leading edges of atmospheric hypersonic vehicles traveling above Mach 5 have motivated an interest in novel thermal management strategies. Here, we use a low-temperature stainless steel-water system to experimentally investigate the feasibility of metallic leading edge heat pipe concepts for thermal management in an efficient load supporting structure. The concept is based upon a two-phase, high thermal conductance “heat pipe” which redistributes the localized thermal flux created at the leading edge stagnation point over a larger surface for effective removal. Structural efficiency is achieved by configuring the system as a wedge-shaped sandwich panel with an I-cell core that simultaneously permits axial vapor and returns liquid flow. The measured axial temperature profiles resulting from a localized thermal flux applied to the tip are consistent with effective thermal spreading that lowered the peak leading edge temperature and reduced the temperature gradients when compared with an equivalent structure containing no working fluid. A simple finite element model that treated the vapor as an equivalent, high thermal conductivity material was in good agreement with these experiments. The model is then used to design a niobium alloy-lithium system that is shown to be suitable for enthalpy conditions representative of Mach 7 scramjet-powered flight. The study indicates that the surface temperature reductions of heat pipe-based leading edges may be sufficient to permit the use of nonablative, refractory metal leading edges with oxidation protection in hypersonic environments.

Nano Heat Pipe: Nonequilibrium Molecular Dynamics Simulation

2016 ◽  
Author(s):  
Mohammad Moulod ◽  
Gisuk Hwang
Keyword(s):  
Molecular Dynamics ◽  
Heat Flux ◽  
Heat Pipe ◽  
Thermal Management ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Nonequilibrium Molecular Dynamics ◽  
Management Systems ◽  
Working Fluid ◽  
Maximum Heat

A heat pipe has been known as a thermal superconductor utilizing a liquid-vapor phase change, and it has drawn significant attentions for advanced thermal management systems. However, a challenge is the size limitation, i.e., the heat pipe cannot be smaller than the evaporator/condenser wick structures, typically an order of micron, and a new operating mechanism is required to meet the needs for the nanoscale thermal management systems. In this study, we design the nanoscale heat pipe employing the gas-filled nanostructure, while transferring heat via ballistic fluid-particle motions with a possible returning working fluid via surface diffusions along the nanostructure. The enhanced heat flux for the nano heat pipe is demonstrated using the nonequilibrium molecular dynamics simulations (NEMDS) for the argon gas confined by the 20 nm-long Pt nanogap with a post wall with the temperature difference between the hot and cold surfaces of 20 K. The predicted results show that the maximum heat flux through the gas-filled nanostructure (heat pipe) nearly doubles that of the nanogap without the post wall at 100 < T < 140 K. The optimal operating conditions/material selections are discussed. The results for the nanogap agree with those obtained from the kinetic theory, and provide insights into the design of advanced thermal management systems.

Feasibility of Metallic Structural Heat Pipes as Sharp Leading Edges for Hypersonic Vehicles

2009 ◽  
Vol 76 (3) ◽  
Author(s):  
Craig A. Steeves ◽  
Ming Y. He ◽  
Scott D. Kasen ◽  
Lorenzo Valdevit ◽  
Haydn N. G. Wadley ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Heat Pipe ◽  
Leading Edge ◽  
Niobium Alloy ◽  
Working Fluid ◽  
Flat Surfaces ◽  
Analytical Approximations ◽  
Fluid Systems ◽  
Edge Surface ◽  
Leading Edges

Hypersonic flight with hydrocarbon-fueled airbreathing propulsion requires sharp leading edges. This generates high temperatures at the leading edge surface, which cannot be sustained by most materials. By integrating a planar heat pipe into the structure of the leading edge, the heat can be conducted to large flat surfaces from which it can be radiated out to the environment, significantly reducing the temperatures at the leading edge and making metals feasible materials. This paper describes a method by which the leading edge thermal boundary conditions can be ascertained from standard hypersonic correlations, and then uses these boundary conditions along with a set of analytical approximations to predict the behavior of a planar leading edge heat pipe. The analytical predictions of the thermostructural performance are verified by finite element calculations. Given the results of the analysis, possible heat pipe fluid systems are assessed, and their applicability to the relevant conditions determined. The results indicate that the niobium alloy Cb-752, with lithium as the working fluid, is a feasible combination for Mach 6–8 flight with a 3 mm leading edge radius.

The Simulation of Heat Pipe Evaporator in Concentration Solar Cell

2010 ◽  
Vol 44-47 ◽  
pp. 1207-1212 ◽  
Author(s):  
Zi Long Wang ◽  
Hua Zhang ◽  
Hai Tao Zhang
Keyword(s):  
Heat Flux ◽  
Solar Cell ◽  
Heat Pipe ◽  
Saturation Temperature ◽  
High Heat ◽  
Maximum Temperature ◽  
Working Fluid ◽  
High Heat Flux ◽  
Two Phase ◽  
Solar Cell Performance

Considering the problem of the concentrating solar cell efficiency restricted by the temperature. The closed two-phase thermosyphon was used to dissipation heat in concentrating solar cell at high heat flux, which adopted water as the working fluid. The temperature distribution of evaporator had significant effect on solar cell performance and heat pipe efficiency. A numerical simulation model of evaporator was established by FLUENT. During the computing process, the heat flux, filling ratio of liquid and saturation temperature were taken into account. It was found that the maximum temperature of evaporator was less than 85°C, when the solar cell operated in 140 to 180 suns, in the conditions of evaporator size (Length×Width×Height, 100×100×30 mm), the optimum charging ratio of liquid is between 27%～30%. The smaller saturation temperature would bring the better heat transfer characters.

scholarly journals Distribution of heat flux by working fluid in loop heat pipe

2016 ◽  
Vol 114 ◽  
pp. 02081
Author(s):  
Patrik Nemec ◽  
Milan Malcho
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Working Fluid ◽  
Loop Heat Pipe

scholarly journals The effect of operating parameters on the heat transfer in the heat pipe

2021 ◽  
Vol 2119 (1) ◽  
pp. 012088
Author(s):  
A. A. Litvintceva ◽  
N. I. Volkov ◽  
N. I. Vorogushina ◽  
V. A. Moskovskikh ◽  
V. V. Cheverda
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Heat Pipes ◽  
Working Fluid ◽  
Operating Parameters ◽  
Temperature Stabilization ◽  
Ir Camera ◽  
Fluid Properties

Abstract Heat pipes are a good solution for temperature stabilization, for example, of microelectronics, because these kinds of systems are without any moving parts. Experimental research of the effect of operating parameters on the heat transfer in a cylindrical heat pipe has been conducted. The effect of the working fluid properties and the porous layer thickness on the heat flux and temperature difference in the heat pipe has been investigated. The temperature field of the heat pipe has been investigated using the IR-camera and K-type thermocouples. The data obtained by IR-camera and K-type thermocouples have been compared. It is demonstrated the power transferred from the evaporator to the condenser is a linear function of the temperature difference between them.

Effect of Fluid Loading on the Performance of Wicked Heat Pipes

Volume 3 ◽  
2004 ◽  
Author(s):  
R. Kempers ◽  
A. Robinson ◽  
C. Ching ◽  
D. Ewing
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Heat Transport ◽  
Heat Pipes ◽  
Working Fluid ◽  
Fluid Loading ◽  
Maximum Heat ◽  
Horizontal Orientation ◽  
Maximum Heat Flux ◽  
Dry Out

A study was performed to experimentally characterize the effect of fluid loading on the heat transport performance of wicked heat pipes. In particular, experiments were performed to characterize the performance of heat pipes with insufficient fluid to saturate the wick and excess fluid for a variety of orientations. It was found that excess working fluid in the heat pipe increased the thermal resistance of the heat pipe, but increased maximum heat flux through the pipe in a horizontal orientation. The thermal performance of the heat pipe was reduced when the amount of working fluid was less than required to saturate the wick, but the maximum heat flux through the heat pipe was significantly reduced at all orientations. It was also found in this case the performance of this heat pipe deteriorated once dry-out occurred.

Numerical Investigation of a Transient Operation of a Heat Pipe With Experimental Validation

2004 ◽  
Author(s):  
Gustavo Gutierrez ◽  
Juan Catan˜o ◽  
Tien-Chien Jen
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Stokes Equations ◽  
Solid Wall ◽  
Control Volume ◽  
Navier Stokes ◽  
Interface Temperature ◽  
Vapor Flow ◽  
Navier Stokes Equation ◽  
Wick Structure

In this paper, a full transient analysis of the performance of a heat pipe with a wick structure is performed. For the vapor flow, the conventional Navier-Stokes equations are used. For the liquid flow in the wick structure, which is modeled as a porous media, volume averaged Navier-Stokes equation are adopted. The energy equation is solved for the solid wall and wick structure of the heat pipe. The energy and momentum equations are coupled through the heat flux at the liquid-vapor interface that defines the suction and blowing velocities for the liquid and vapor flow. The evolution of the vapor-liquid interface temperature is coupled through the heat flux at this interface that defines the mass flux to the vapor and the new saturation conditions to maintain a fully saturation vapor all the time. A control volume approach is used in the development of the numerical scheme. A parametric study is conducted to study the effect of different parameters that affect the thermal performance of the heat pipe. And experimental setup is developed and numerical results are validated with experimental data. The results of this study will be useful for the heat pipe design and implementation in processes that are essentially transient and steady state conditions are not reached like for example drilling applications.

Effect of Heat Leading of Windward Leading Edge Using Heat Pipe with Porous

2011 ◽  
Vol 217-218 ◽  
pp. 674-679
Author(s):  
Jian Sun ◽  
Wei Qiang Liu
Keyword(s):  
Heat Pipe ◽  
Thermal Load ◽  
Thermal Protection ◽  
Leading Edge ◽  
Heat Pipes ◽  
Maximum Temperature ◽  
Equivalent Thermal Conductivity ◽  
Volume Method ◽  
Black Level ◽  
Selection Of

By the uses of finite element method and finite volume method, we calculated the solid domain and fluid domain of windward leading edge which is flying under one condition. And the paper proved that heat pipes which covered on the leading edge have effect on thermal protection. The maximum temperature of the head decreased 12.2%. And the minimum temperature of after-body increased 8.85%. Achieving the transfer of heat from head to after-body, the front head of the thermal load was weakened and the ability of leading edge thermal protection was strengthen. The effect of the thickness of heat pipe, black level of covering materials and equivalent thermal conductivity of heat pipes on the wall temperature were discussed for the selection of thermal protection materials of windward leading edge to provide a frame of reference.

Gravity-Assisted Heat Pipe With Strong Marangoni Fluid for Waste Heat Management of Single and Dual-Junction Solar Cells

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Kenneth M. Armijo ◽  
Van P. Carey
Keyword(s):  
Heat Flux ◽  
Solar Cells ◽  
Heat Pipe ◽  
Waste Heat ◽  
Working Fluid ◽  
Water Mixture ◽  
Heat Management ◽  
Strong Concentration ◽  
Electrical Efficiency ◽  
Pipe System

This study investigates the cooling of single and multijunction solar cells with an inclined, gravity-assisted heat pipe, containing a 0.05 M 2-propanol/water mixture that exhibits strong concentration Marangoni effects. Heat pipe solar collector system thermal behavior was investigated theoretically and semi-empirically through experimentation of varying input heat loads from attached strip-heaters to simulate waste heat generation of single-junction monocrystalline silicon (Si), and dual-junction GaInP/GaAs photovoltaic (PV) solar cells. Several liquid charge ratios were investigated to determine an optimal working fluid volume that reduces the evaporator superheat while enhancing the vaporization transport heat flux. Results showed that a 45% liquid charge, with a critical heat flux of 114.8 W/cm2, was capable of achieving the lowest superheat levels, with a system inclination of 37 deg. Solar cell semiconductor theory was used to evaluate the effects of increasing temperature and solar concentration on cell performance. Results showed that a combined PV/heat pipe system had a 1.7% higher electrical efficiency, with a concentration ratio 132 suns higher than the stand-alone system. The dual-junction system also exhibited enhanced performance at elevated system temperatures with a 2.1% greater electrical efficiency, at an operational concentration level 560 suns higher than a stand-alone system.

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