Thermal Design and Testing of a Passive Helmet Heat Exchanger With Additively Manufactured Components

2018 ◽  
Author(s):  
Kailyn Cage ◽  
Monifa Vaughn-Cooke ◽  
Mark Fuge ◽  
Briana Lucero ◽  
Dusan Spernjak ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Thermal Management ◽  
Heat Pipes ◽  
Thermal Design ◽  
Analytical Models ◽  
Small Scale ◽  
Dimensional System ◽  
Concept Design ◽  
Environmental Chamber

Additive manufacturing (AM) processes allow for complex geometries to be developed in a cost- and time-efficient manner in small-scale productions. The unique functionality of AM offers an ideal collaboration between specific applications of human variability and thermal management. This research investigates the intersection of AM, human variability and thermal management in the development of a military helmet heat exchanger. A primary aim of this research was to establish the effectiveness of AM components in thermal applications based on material composition. Using additively manufactured heat pipe holders, the thermal properties of a passive evaporative cooler are tested for performance capability with various heat pipes over two environmental conditions. This study conducted a proof-of-concept design for a passive helmet heat exchanger, incorporating AM components as both the heat pipe holders and the cushioning material targeting internal head temperatures of ≤ 35°C. Copper heat pipes from 3 manufactures with three lengths were analytically simulated and experimentally tested for their effectiveness in the helmet design. A total of 12 heat pipes were tested with 2 heat pipes per holder in a lateral configuration inside a thermal environmental chamber. Two 25-hour tests in an environmental chamber were conducted evaluating temperature (25°C, 45°C) and relative humidity (25%, 50%) for the six types of heat pipes and compared against the analytical models of the helmet heat exchangers. Many of the heat pipes tested were good conduits for moving the heat from the head to the evaporative wicking material. All heat pipes had Coefficients of Performance under 3.5 when tested with the lateral system. Comparisons of the analytical and experimental models show the need for the design to incorporate a re-wetting reservoir. This work on a 2-dimensional system establishes the basis for design improvements and integration of the heat pipes and additively manufactured parts with a 3-dimensional helmet.

Metallic Mesh as Capillary Structure Applied in Heat Pipe Heat Exchanger for Heat Recovery

2014 ◽  
Vol 1082 ◽  
pp. 309-314 ◽  
Author(s):  
Diogo L.F. Santos ◽  
Larissa S. Marquardt ◽  
Paulo H.D. Santos ◽  
Thiago Antonini Alves
Keyword(s):  
Stainless Steel ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Working Fluid ◽  
Capillary Structure ◽  
Porous Wick ◽  
Metallic Mesh ◽  
Heat Loads ◽  
Pipe Heat

This work presents a theoretical and experimental analysis of a heat exchanger assisted by five heat pipes made of copper with a metallic mesh 100 of stainless steel which was used as capillary structure. All heat pipes used water as the working fluid and were designed based on the capillary limit model. The heat pipes were developed and tested under heat loads varying from 20 to 50 W before application into the heat exchanger. The theoretical and experimental results were compared and all heat pipes worked satisfactorily. Thereafter, it is presented the development of heat pipe heat exchanger which was tested under heat loads varying from 100 to 250 W. The highest temperature measured on the external surface of the heat pipes was 90 oC and the heat exchanger thermal efficiency varied from 74 to 80%. It is showed that the use of a stainless steel mesh as a porous wick was proved to work successfully in heat pipes.

Development and Application of a Thin Flat Heat Pipe Design Optimization Tool for Small Satellite Systems

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Steven A. Isaacs ◽  
Caelan Lapointe ◽  
Peter E. Hamlington
Keyword(s):  
Computational Modeling ◽  
Cost Function ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Operating Conditions ◽  
Small Scale ◽  
Small Satellite ◽  
Modeling And Optimization ◽  
Satellite Systems ◽  
Flat Heat Pipe

Abstract With easier access to space and the growing integration of power-dense components, small-scale thermal management solutions are increasingly in demand for small satellite systems. Due to the strict mass and volume requirements commanded by such power-dense small spacecraft, heat pipes with thin and flat architectures provide nearly ideal solutions for the efficient transfer and dissipation of heat. Unlike traditional heat pipes, however, the performance of thin heat pipes is heavily dependent on details of the internal heat pipe structure, including the vapor core geometry and structural mechanical characteristics. In this study, the development and testing of a new computational modeling and optimization tool are presented for the design of thin flat heat pipes. The computational model is described in detail and includes parameters that define properties of the liquid wick, vapor core, and structural case. The model is coupled to a gradient-based optimization procedure that minimizes a multi-objective cost function for a range of operating conditions. The cost function is expressed as the weighted sum of the total temperature drop, the liquid/vapor pressure ratio, the total mass of the heat pipe, and the structural deflection of the heat pipe during operation. The combined computational modeling and optimization tool is then used to design a copper-methanol flat heat pipe for a small satellite mission, where the optimization is performed with respect to both cold and hot orbital conditions. Validation of the optimized heat pipe is performed using computational fluid dynamics (CFD) simulations of the initial and final designs.

Thermal Management of a Heat-Pipe Drill: A FEM Analysis

2003 ◽  
Author(s):  
Tien-Chien Jen ◽  
Rajendra Jadhav
Keyword(s):  
Finite Element ◽  
Heat Pipe ◽  
Thermal Management ◽  
Heat Pipes ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Drilling Process ◽  
Generation Process ◽  
Finite Element Software

Thermal management using heat pipes is gaining significant attention in past decades. This is because of the fact that it can be used as an effective heat sink in very intricate and space constrained applications such as in electronics cooling or turbine blade cooling where high heat fluxes are involved. Extensive research has been done in exploring various possible applications for the use of heat pipes as well as understanding and modeling the behavior of heat pipe under those applications. One of the possible applications of heat pipe technology is in machining operations, which involves a very high heat flux being generated during the chip generation process. Present study focuses on the thermal management of using a heat pipe in a drill for a drilling process. To check the feasibility and effectiveness of the heat pipe drill, structural and thermal analyses are performed using Finite Element Analysis. Finite Element Software ANSYS was used for this purpose. It is important for any conceptual design to be made practical and hence a parametric study was carried out to determine the optimum geometry size for the heat pipe for a specific standard drill.

A Simplified Conduction Based Modeling Scheme for Design Sensitivity Study of Thermal Solution Utilizing Heat Pipe and Vapor Chamber Technology

2003 ◽  
Vol 125 (3) ◽  
pp. 378-385 ◽  
Author(s):  
Ravi S. Prasher
Keyword(s):  
Heat Pipe ◽  
Temperature Drop ◽  
Heat Pipes ◽  
Sensitivity Study ◽  
Design Sensitivity ◽  
Thermal Design ◽  
Vapor Chamber ◽  
Modeling Tools ◽  
Heating Source ◽  
Thermal Solution

This paper introduces a simplified modeling scheme for the prediction of heat transport capability of heat pipes and vapor chambers. The modeling scheme introduced in this paper enables thermal designers to model heat pipes and vapor chambers in commercially available conduction modeling tools such as Ansys™ and IcePak™. This modeling scheme allows thermal designers to perform design sensitivity studies in terms of power dissipation of heat pipes and vapor chambers for different scenarios such as configurations, heat sink resistance for a given temperature drop between the heating source and the ambient. This paper also discusses how thermal designers can specify requirements to heat pipe/vapor chamber suppliers for their thermal design, without delving into the complete thermo-fluidic modeling of this technology.

Applying heat pipes to a novel concept aero engine: Part 1 – Design of a heat-pipe heat exchanger for an intercooled aero engine

2011 ◽  
Vol 115 (1169) ◽  
pp. 393-402 ◽  
Author(s):  
R. Camilleri ◽  
S. Ogaji ◽  
P. Pilidis
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Fuel Efficiency ◽  
Heat Pipes ◽  
Civil Aviation ◽  
Pressure Losses ◽  
Aero Engine ◽  
Core Concepts ◽  
Novel Concept ◽  
Pipe Heat

Abstract Civil aviation has instilled new perceptions of a smaller world, creating new opportunities for trade, exchange of cultures and travelling for leisure. However, it also brought with it an unforeseen impact on the environment. Aviation currently contributes to about 3·5% of the global warming attributed from human activities. With the forecasted rate of growth, this is expected to rise to about 15% over the next 50 years. Although it is projected that the annual improvements in aircraft fuel efficiency are of the order of 1-2%, it is suggested that the current gas turbine design is fully exploited and further improvements are difficult to achieve. A new generation of aero engine core concepts that can operate at higher thermal efficiencies and lower emissions is required. One possibility of achieving higher core efficiencies is through the use of an inter-cooled (IC) core at high overall pressure ratios (OPR). The concept engine, expected to enter into service around 2020, will make use of a conventional heat exchanger (HEX) for the intercooler. This paper seeks to introduce a heat pipe heat exchanger (HPHEX) as an alternative design of the intercooler. The proposed HPHEX design takes advantage of the convenience of the geometry of miniature heat pipes to provide a reduction in pressure losses and weight when compared to conventional HEX. The HPHEX will be made of a number of stages, each stage being made of a large number of miniature heat pipes in radial configuration, that will extend from the inter-compressor duct to the bypass split, thus eliminating any ducting to and from the intercooler. This design offers up to 32% reduction in hot pressure losses, 34% reduction in cold pressure losses and over 41% reduction in weight.

scholarly journals Staying Cool

1999 ◽  
Vol 121 (07) ◽  
pp. 64-65
Author(s):  
Calvin C. Silverstein
Keyword(s):  
Heat Pipe ◽  
Thermal Management ◽  
Liquid Flow ◽  
High Performance ◽  
Heat Pipes ◽  
Flow Channel ◽  
Aircraft Engines ◽  
Chemical Milling ◽  
Combination Of Methods ◽  
Half Thickness

This article reviews heat pipes that address thermal management problems inside high-performance aircraft engines. Higher performance engines demand that compressors develop higher pressure ratios which, in turn, result in higher temperatures at the entrance to the combustor. CCS Associates of Bethel Park, PA, proposes tackling the problem by using pipes to distribute heat more effectively throughout the combustor. The heat pipe liner must handle both acceleration and vibration. The heat pipe arrays, including half-thickness webs, can be fabricated into gas-side and air-side halves by extrusion, forging, stamping, chemical milling, or some combination of methods. The liquid flow channel would be formed as an integral part of the gas-side valves.

scholarly journals Experimental and Numerical Study of Heat Pipe Heat Exchanger with Individually Finned Heat Pipes

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5317
Author(s):  
Grzegorz Górecki ◽  
Marcin Łęcki ◽  
Artur Norbert Gutkowski ◽  
Dariusz Andrzejewski ◽  
Bartosz Warwas ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Numerical Study ◽  
Heat Pipes ◽  
Relative Difference ◽  
Working Fluid ◽  
Staggered Arrangement ◽  
Brute Force Method ◽  
Air Conditioning Systems ◽  
Pipe Heat

The present study is devoted to the modeling, design, and experimental study of a heat pipe heat exchanger utilized as a recuperator in small air conditioning systems (airflow ≈ 300–500 m3/h), comprised of individually finned heat pipes. A thermal heat pipe heat exchanger model was developed, based on available correlations. Based on the previous experimental works of authors, refrigerant R404A was recognized as the best working fluid with a 20% heat pipe filling ratio. An engineering analysis of parametric calculations performed with the aid of the computational model concluded 20 rows of finned heat pipes in the staggered arrangement as a guarantee of stable heat exchanger effectiveness ≈ 60%. The optimization of the overall cost function by the “brute-force” method has backed up the choice of the best heat exchanger parameters. The 0.05 m traversal (finned pipes in contact with each other) and 0.062 m longitudinal distance were optimized to maximize effectiveness (up to 66%) and minimize pressure drop (less than 150 Pa). The designed heat exchanger was constructed and tested on the experimental rig. The experimental data yielded a good level of agreement with the model—relative difference within 10%.

Design Optimization of Micro-channel Heat Exchanger embedded in LTCC

2012 ◽  
Vol 2012 (1) ◽  
pp. 000857-000865
Author(s):  
Aparna Aravelli ◽  
Singiresu S. Rao ◽  
Hari K. Adluru
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Management ◽  
Optimization Technique ◽  
Thermal Design ◽  
Transfer Rates ◽  
Design Variables ◽  
Micro Heat Exchanger ◽  
Micro Systems ◽  
Silver Metal

Increase in the density of electronic packaging leads to the investigation of highly efficient thermal management systems. The challenge in these micro-systems is to maximize heat transfer per unit volume. In the author's previous work, experimental and computational analysis has been performed on LTCC substrates using embedded silver vias. This novel technique of embedding silver vias along with forced convection resulted in higher heat transfer rates. The present work further investigates into the optimization of this model. A Multi-objective optimization problem has been formulated for the heat transfer in the LTCC model. The Log Mean Temperature Difference (LMTD) method of heat exchangers has been used in the formulation. Optimization is done based on maximization of the total heat transferred and minimization of the coolant pumping power. Structural and thermal design variables are considered to meet the manufacturability and energy requirements. Demanded pressure loss and volume of the silver metal are used as constraints. The classical optimization technique Sequential Quadratic Programming (SQP) is used to solve the micro-heat exchanger problem. The optimal design is presented and sensitivity analysis results are discussed.

An Experimental Verification of a Conceptual Heat-Pipe Radiator

1993 ◽  
Vol 115 (4) ◽  
pp. 272-277
Author(s):  
T. S. Ravigururajan ◽  
M. L. Goryca
Keyword(s):  
Heat Pipe ◽  
Waste Heat ◽  
Peak Load ◽  
Heat Pipes ◽  
Experimental Tests ◽  
Small Scale ◽  
Vehicle Speed ◽  
Air Velocity ◽  
Surrounding Environment ◽  
Wide Range

The radiator and its vulnerability to damage is one of the main criteria in automotive design. This study employed heat pipes in simulated radiators to transfer waste heat to the surrounding environment. A small-scale heat-pipe radiator module was designed using a computer program. Experimental tests were performed on this module to validate the design methodology and to study the vulnerability characteristics. The tests were conducted for a wide range of operating parameters such as air velocity, coolant flow rates, and the number of heat pipes damaged. The study indicated that a heat-pipe radiator may provide the necessary “limp home” capability to a vehicle, even with 50 percent of the pipes damaged. Also, with the radiators operating at less than peak load (slower vehicle speed), the undamaged heat pipes substantially compensated for the damaged heat pipes, adding to the reliability of the system.

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