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.

Waste Heat Recovery for Powering Mobile Devices Using Thermoelectric Generators and Evaporatively-Cooled Heat Sink

2018 ◽  
Author(s):  
Michael Ozeh ◽  
A. G. Agwu Nnanna
Keyword(s):  
Heat Pipe ◽  
Mobile Devices ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Pipes ◽  
Loop Heat Pipe ◽  
Thermoelectric Voltage ◽  
Voltage Generation ◽  
Alternate Source

Powering small electronics like mobile devices off-grid has remained a challenge; hence, there exists a need for an alternate source of powering these devices. This paper examines the efficacy of a novel nanoparticle-immobilized polyethylene wick in maintaining sufficient thermal gradient across a thermoelectric generator to power these devices with energy from waste heat. The work examines several other heat exchangers including heat pipes and loop heat pipe setups. The experimental evidence reveals that the nanoparticle-immobilized polyethylene wick is capable of generating sufficient thermal potential resulting in 5V, which is the minimum voltage required to power small mobile devices. In the opinion of the authors, this is the first ever recorded account of utilizing waste heat to generate enough voltage to power a mobile device. Experiment demonstrated that the nanoparticle-immobilized polyethylene wick showed over 40% thermoelectric voltage generation increment over a plain polyethylene wick and a metal wick in a loop heat pipe setup.

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.

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.

Conversion of Syngas From Biomass in Solid Oxide Fuel Cells

2006 ◽  
Author(s):  
Ju¨rgen Karl ◽  
Nadine Frank ◽  
Sotiris Karellas ◽  
Mathilde Saule ◽  
Ulrich Hohenwarter
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Liquid Metal ◽  
Waste Heat ◽  
Heat Pipes ◽  
Economic Feasibility ◽  
Small Scale ◽  
Cell Systems ◽  
Exhaust Heat ◽  
Integrated Gasification

Conversion of biomass in syngas by means of indirect gasification offers the option to improve the economic situation of any fuel cell systems due to lower costs for feedstock and higher power revenues in many European countries. The coupling of an indirect gasification of biomass and residues with highly efficient SOFC systems is therefore a promising technology for reaching economic feasibility of small decentralized combined heat and power production (CHP). The predicted efficiency of common high temperature fuel cell systems with integrated gasification of solid feedstock is usually significantly lower than the efficiency of fuel cells operated with hydrogen or methane. Additional system components like the gasifier, as well as the gas cleaning reduce this efficiency. Hence common fuel cell systems with integrated gasification of biomass will hardly reach electrical efficiencies above 30 percent. An extraordinary efficient combination is achieved in case that the fuel cells waste heat is used in an indirect gasification system. A simple combination of a SOFC and an allothermal gasifier enables then electrical efficiencies above 50%. But this systems requires an innovative cooling concept for the fuel cell stack. Another significant question is the influence of impurities on the fuel cells degradation. The European Research Project ‘BioCellus’ focuses on both questions — the influence of the biogenious syngas on the fuel cells and an innovative cooling concept based on liquid metal heat pipes. First experiments showed that in particular higher hydrocarbons — the so-called tars — do not have an significant influence on the performance of SOFC membranes. The innovative concept of the TopCycle comprises to heat an indirect gasifier with the exhaust heat of the fuel cell by means of liquid metal heat pipes. Internal cooling of the stack and the recirculation of waste heat increases the system efficiency significantly. This concept promises electrical efficiencies of above 50 percent even for small-scale systems without any combined processes.

Applying CHP to the Ventilation Air of Buildings

2003 ◽  
Author(s):  
Matthew Cowie ◽  
Xiaohong Liao ◽  
Reinhard Radermacher
Keyword(s):  
Capital Investment ◽  
Waste Heat ◽  
Peak Load ◽  
Industrial Sector ◽  
Capital Cost ◽  
Energy Requirements ◽  
Small Scale ◽  
Commercial Building ◽  
Diverse Range ◽  
Chp System

There is a strong industry focus on packaged CHP systems for small scale applications where the design time for unique installations cannot be justified. Distributed generators such as microturbines, reciprocating engines and fuel cells can all now be purchased as CHP products. The development of these products will bring the energy, environmental and economic savings realized in larger applications to the smaller consumers. CHP systems traditionally operate most effectively and give the shortest payback when operated continuously at full output in a baseloading application. This is in conflict with a typical commercial building whose energy requirements vary extensively over daily, weekly and seasonal time periods. Just as CHP is not expected to supply the entire energy requirements of the industrial sector, so CHP should be looked at as merely part of the energy mix for the commercial sector as the capital cost of CHP equipment is typically higher compared to its alternatives and there are technical complications to supply a heating or cooling to power ratio away from design values. An economic CHP system must therefore have a capacity much lower than the peak load of the building to ensure high utilization of the system so that the larger capital investment can be recovered through energy cost savings as quickly as possible. In the absence of a year round continuous demand for either hot or chilled water a commercial CHP system must offer a diverse range of outputs so that the waste heat from the generator can be utilized as mush as possible particularly since the generator component is likely to dominate the capital cost of the installation. This paper proposes that the outdoor, or ventilation air stream into a building provides an excellent capacity match for CHP equipment packaged as a CHP Dedicated Outdoor Air System (CHPDOAS). Ventilation air has the largest temperature and humidity difference with indoor air of any stream of air in the building and so reduces the heat and mass transfer surface areas in the equipment. Also since the ventilation air is only a fraction of the total air flow rate that is being conditioned the CHP system can overcool the air in the summer or overheat the air in the winter and the effect is simply the reduce the cooling or heating workload of the conventional equipment since the ventilation air is then mixed with the bulk of the air remaining in the building before being conditioned. This means that the CHP system can run its generator for longer hours and at higher loads than would have been possible if the outlet conditions were set at space neutral or space supply conditions.

scholarly journals Effect of heat pipe failure on performance of residual heatremoval system with heat pipe for small lead-based reactor

2021 ◽  
Vol 248 ◽  
pp. 01021
Author(s):  
Chongju Hu ◽  
Hongyan Wang ◽  
Bo Wu ◽  
Xiuxiang Zhang ◽  
Pinghua Zhang
Keyword(s):  
Heat Pipe ◽  
Waste Heat ◽  
Heat Removal ◽  
Heat Pipes ◽  
Normal Operation ◽  
Pipe Failure ◽  
The Core ◽  
External Power ◽  
Heat Removal System ◽  
Removal System

Heat pipe have the characteristics of high thermal conductivity, high safety performance, without external power, etc. In this paper, The numerical simulation CFD software FLUENT is used to study the thermal-hydraulic characteristics performance of heat pipe waste heat removal system with heat pipe for lead-based reactor under normal conditions and Station-Black-Out (SBO) with partial heat pipes damage respectively. Results showed that heat pipes promote heat transfer in the reactor and reduced the temperature of the fluid around the reactor during normal operation; Heat in the core could be removed smoothly by the PRHRS during SBO accident without heat pipe damage ; and when the proportion of failed heat pipes is less than 50% during SBO accident , the PRHRS could still ensure safe operation of the reactor and the distribution of failed heat pipes in the reactor results the core temperature variation by less than 5 K.

scholarly journals Experimental investigation of a heat pipe heat exchanger for heat recovery

2018 ◽  
Vol 45 ◽  
pp. 00012
Author(s):  
Anna Bryszewska-Mazurek ◽  
Wojciech Mazurek
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Working Fluid ◽  
Air Velocity ◽  
Condensation Zone ◽  
Evaporation Zone ◽  
Air Stream ◽  
Face Velocity ◽  
Pipe Heat

An air-to-air heat pipe heat exchanger has been designed, constructed and tested. Gravity-assisted wickless heat pipes (thermosiphons) were used to transfer heat from one air stream to another air stream, with a low temperature difference. A thermosiphon heat exchanger has its evaporation zone below the condensation zone. Heat pipes allow keeping a more uniform temperature in the heat transfer area. The heat exchanger consists of 20 copper tubes with circular copper fins on their outer surface. The tubes were arranged in a row and the air passed across the pipes. R245fa was used as a working fluid in the thermosiphons. Each heat pipe had a 40 cm evaporation section, a 20 cm adiabatic section and a 40 cm condensation section. The thermosiphon heat exchanger has been tested in different conditions of air stream parameters (flows, temperatures and humidity). The air face velocity ranged from 1,0 m/s to 4,0 m/s. The maximum thermal efficiency of the thermosiphon heat exchanger was between 26÷40%, depending on the air velocity. The freezing of moisture from indoor air was observed when the cold air temperature was below - 13°C.

scholarly journals Passive Cooling Solutions for High Power Server CPUs with Pulsating Heat Pipe Technology: Review

2021 ◽  
Vol 9 ◽  
Author(s):  
Chenxi Li ◽  
Ji Li
Keyword(s):  
Heat Pipe ◽  
High Power ◽  
Data Centers ◽  
Heat Dissipation ◽  
Waste Heat ◽  
Smart Cities ◽  
Heat Pipes ◽  
Passive Cooling ◽  
Pulsating Heat Pipe ◽  
Compact Structure

Data centers are becoming more powerful and more integrated with the continuous development of smart cities, which brings us more technological convenience, but also generates a large amount of waste heat. At present, the efficient and green cooling scheme is one of the key researches and development points to ensure the stable and safe operation of power electronic devices and achieve energy saving and consumption reduction. As a branch of the heat pipe, the pulsating heat pipe is one of most promising passive cooling techniques among many candidates for its unique advantages such as small size, simple and compact structure, and high heat dissipation efficiency, but its application in data centers just begins, and there are few reports on research and implementation. Based on the introduction of the basic structure, working mechanism and outstanding advantages of pulsating heat pipes, this paper reviews in detail the researches on the factors affecting its performance, so as to evaluate the possibility of using pulsating heat pipes in data centers. Finally, the latest application and development of pulsating heat pipes applied to heat dissipation of high-power CPUs are summarized, which can provide a guidance for subsequent research and engineering application.

Conversion of Syngas From Biomass in Solid Oxide Fuel Cells

2009 ◽  
Vol 6 (2) ◽  
Author(s):  
Jurgen Karl ◽  
Nadine Frank ◽  
Sotirios Karellas ◽  
Mathilde Saule ◽  
Ulrich Hohenwarter
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Liquid Metal ◽  
Waste Heat ◽  
Heat Pipes ◽  
Solid Oxide ◽  
Small Scale ◽  
Oxide Fuel ◽  
Cell Systems ◽  
Integrated Gasification

Conversion of biomass in syngas by means of indirect gasification offers the option to improve the economic situation of any fuel cell system due to lower costs for feedstock and higher power revenues in many European countries. The coupling of an indirect gasification of biomass and residues with highly efficient solid oxide fuel cell (SOFC) systems is therefore a promising technology for reaching economic feasibility of small decentralized combined heat and power production (CHP).The predicted efficiency of common high temperature fuel cell systems with integrated gasification of solid feedstock is usually significantly lower than the efficiency of fuel cells operated with hydrogen or methane. Additional system components like the gasifier as well as the gas cleaning reduce this efficiency. Hence common fuel cell systems with integrated gasification of biomass will hardly reach electrical efficiencies above 30%. An extraordinary efficient combination is achieved in case that the fuel cells waste heat is used in an indirect gasification system. A simple combination of a SOFC and an allothermal gasifier enables then electrical efficiencies above 50%. However, this system requires an innovative cooling concept for the fuel cell stack. Another significant question is the influence of impurities on the fuel cell degradation. The European Research Project “BioCellus” focuses on both questions—the influence of the biogenous syngas on the fuel cells and an innovative cooling concept based on liquid metal heat pipes. First experiments showed that, in particular, higher hydrocarbons—the so-called tars—do not have any significant influence on the performance of SOFC membranes. The innovative concept of the TopCycle comprises to heat an indirect gasifier with the exhaust heat of the fuel cell by means of liquid metal heat-pipes. Internal cooling of the stack and the recirculation of waste heat increases the system efficiency significantly. This concept promises electrical efficiencies of above 50% even for small-scale systems without any combined processes.

The Design of Heat Pipe Heat Exchanger for CO2 EGS

2013 ◽  
Vol 479-480 ◽  
pp. 284-288
Author(s):  
Jui Ching Hsieh ◽  
David T.W. Lin ◽  
Wei Mon Yan ◽  
Long Der Shin
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Geothermal System ◽  
Enhanced Geothermal System ◽  
Air Velocity ◽  
Hot Gas ◽  
Experimental Apparatus ◽  
New Energy ◽  
Pipe Heat

The findings of new energy and energy harvester are the important issues for the lacking of fossil energy. For the purpose of the effective usage of supercritical CO2flowed from the product well of CO2EGS (Enhanced Geothermal System), an innovative heat pipe heat exchanger (Hx) is designed and practiced in this study. This study presents an innovative Hx of heat pipe for extracting the heat from CO2or warm gas. By using the heat pipe for cooling gas is the fundamental idea of this Hx. The experimental apparatus of Hx consists a heating blower to blow out hot gas, a circulating cool water device, and a set of heat pipes. The efficiency of Hx is approved as the increasing air velocity and the more fins gradually. This innovative heat pipe exchanger is proofed through our experiment. This heat pipe Hx is suitable for the application of enhanced geothermal system (EGS) and more energy harvesting application.

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