Carbon Nanotube Arrays for Enhanced Thermal Interfaces to Thermoelectric Modules

Saviers, Kimberly R.; Hodson, Stephen L.; Fisher, Timothy S.; Salvador, James R.; Kasten, L.S.

doi:10.2514/1.t4026

Cited by 13 publications

(6 citation statements)

References 39 publications

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“…A range for each evaluation area was investigated for the normal and enhanced contact conductance and 1.32 T/2 T applied field. The typical contact conductance between NdFeB and Gd (650 W/(m 2 K)) was reported [10], and in this study, we use an enhanced contact conductance (2000 W/(m 2 K)) to represent thermal interface materials such as carbon nanotubes or heat spreaders [27]. The contact resistance was applied to the boundary between the heat source and Gd as well as the boundary between the Gd and heat sink using Eqs.…”

Section: (A) a 360-deg Revolution Of The 2d Axisymmetric Model Results In The 3d Formation (Figs 2(b) And 2(c))mentioning

confidence: 99%

Numerical Analysis of an Active Thermomagnetic Device for Thermal Energy Harvesting

Phillips

Carman

2020

Journal of Energy Resources Technology

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The abundance of low-grade waste heat necessitates energy harvesting devices to convert thermal energy to electrical energy. Through magnetic transduction, thermomagnetics can perform this conversion at reasonable efficiencies. Thermomagnetic materials use thermal energy to switch between magnetic and non-magnetic states and convert thermal energy into electrical energy. In this study, we numerically analyzed an active thermomagnetic device for thermal energy harvesting composed of gadolinium (Gd) and neodymium iron boron (NdFeB). A parametric study to determine the device efficiency was conducted by varying the gap distance, heat source temperature, and Gd thickness. Furthermore, the effect of the thermal conductance and applied field was also evaluated. It was found that the relative efficiency for smaller gap distances ranges from ∼15% to 28%; the largest allowable volume of Gd should be used and higher applied field leads to higher efficiencies.

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Section: (A) a 360-deg Revolution Of The 2d Axisymmetric Model Results In The 3d Formation (Figs 2(b) And 2(c))mentioning

confidence: 99%

Numerical Analysis of an Active Thermomagnetic Device for Thermal Energy Harvesting

Phillips

Carman

2020

Journal of Energy Resources Technology

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“…The interface between a metal and nonmetal is becoming an increasingly important consideration in a variety of applications, such as thermoelectric devices [17,19] and hightemperature fuel cells [43]. Direct bonding is often difficult due to highly mismatched thermal expansion coefficients.…”

Section: Resultsmentioning

confidence: 99%

“…Using a mechanically compliant thermal interface material provides an alternative solution when thermal transport is critical and the joint does not bear a large load. An example is the hot-side interface between a dielectric layer and heat exchanger in a high-temperature thermoelectric generator [17,19].…”

Section: Resultsmentioning

confidence: 99%

“…Thermoelectric generation (TEG) is being used increasingly with higher temperature heat sources in order to obtain better efficiency and more power output [15,16]. For example, recent research programs aim to harvest the waste energy in automobile exhaust gas (>600˚C) using TEG [17][18][19]. The actual temperature at the hot-side junction of the thermoelectric device is often much lower than that of the heat source, mainly because of the high thermal resistance of various interfaces between them, and the high-temperature environment dictates that traditional organic-material TIMs cannot be used.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of vertically oriented carbon nanotube arrays as high-temperature thermal interface materials

Hao

Huang

Saviers

et al. 2017

International Journal of Heat and Mass Transfer

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Carbon nanotube arrays hold much potential for high-temperature thermal interface applications that require thermal stability and mechanical compliance. A 1D reference bar test rig designed for measurements at and substantially above room temperature is used to perform thermal cycling tests on CNT arrays and to measure their thermal interface resistance at temperatures up to 700˚C. The CNT arrays are synthesized and tested with both thermomechanically matched (Cu-Cu) and mismatched (alumina-Cu) interfaces to examine their mechanical compliance. For both cases, a moderate decrease in thermal interface resistance (TIR) occurs from room temperature to 700˚C. The results reveal good cyclic stability of CNT arrays in both cases, confirming their ability to accommodate large thermomechanical mismatch. Postmortem analysis indicates that CNT free ends conform to the opposing Cu surface. In the Cu-Cu interface, only compressive deformation of the CNT arrays is observed. In the alumina-Cu interface, more complex thermomechanical deformation occurs that is hypothesized to be a combined effect of compressive loading and shear stress.

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“…As explained earlier in Section 1, having a separate heat source as in traditional RTGs needs a thermal interface between the heat source and the thermoelectric elements, whereas such a thermal interface is completely eliminated in our case. Making a good thermal interface in traditional thermoelectric generators is not a trivial task, and it has been shown that the quality of the thermal interface indeed greatly affects the performance, up to 60% . Further elaboration and optimization of the design must follow in order to realize a practical device based on this concept.…”

Section: Discussionmentioning

confidence: 99%

Power generation characteristics of a sandwich-type self-heating thermoelectric generator with spatially varying embedded heat source

Shin

Bang

Choi

et al. 2015

Int. J. Energy Res.

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SUMMARYPower generation characteristics of a sandwich-type thermoelectric generator in which the heat source is embedded into thermoelectric elements are investigated. Our previous work on a similar concept only considered a uniform heat source distribution inside thermoelectric elements. In this work, the effect of the spatial distribution of a heat source is examined. In particular, the effect of the concentration of heat source near the one end, that is, the hot end, is intensively studied as a potential means of improving the efficiency of the device.Although the effects of heat source concentration in impractical cases without heat transfer limitations on the cold side remain ambiguous, it become clear that heat source concentration indeed has positive effects in more realistic cases with finite heat transfer coefficients imposed on the cold side. Because of the relatively low efficiency of typical thermoelectric generation, a significant amount of heat must be dissipated from the cold end of the thermoelectric element. Greater heat source concentration near the hot end leads to more effective utilization of available heat source, reduces the amount of heat rejected at the cold end, and lowers the hot end temperature of the thermoelectric element. Overall, it is suggested that heat source concentration can be used as a method to achieve more efficient operation and better structural integrity of the system.

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Carbon Nanotube Arrays for Enhanced Thermal Interfaces to Thermoelectric Modules

Cited by 13 publications

References 39 publications

Numerical Analysis of an Active Thermomagnetic Device for Thermal Energy Harvesting

Numerical Analysis of an Active Thermomagnetic Device for Thermal Energy Harvesting

Characterization of vertically oriented carbon nanotube arrays as high-temperature thermal interface materials

Power generation characteristics of a sandwich-type self-heating thermoelectric generator with spatially varying embedded heat source

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