Cooling power optimization for hybrid solid-state and liquid cooling in integrated circuit chips with hotspots

Yazawa, Kazuaki; Ziabari, Amirkoushyar; Koh, Yee Rui; Shakouri, Ali; Sahu, Vivek; Fedorov, Andrei G.; Joshi, Yogendra

doi:10.1109/itherm.2012.6231419

Cited by 13 publications

(15 citation statements)

References 9 publications

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“…In micro-refrigeration, an important problem is the fact of handle heat flux in a small space and it has been proved that thermal interface resistance has beneficial or detrimental effects on cooling performance [34]. For calculation, contact resistances between stages are not considered, since it is known that thermal resistances exist in the interfaces, which are large when the cross-sectional areas are very dissimilar in the stages and negligible for similar cross-sectional areas [35,36]. Present work can be useful as theoretical…”

Section: Optimization Analysis According To the Geometric Parameter Wmentioning

confidence: 99%

Thermoelectric Cooling: The Thomson Effect in Hybrid Two- Stage Thermoelectric Cooler Systems with Different Leg Geometric Shapes

Ruiz-Ortega¹,

Olivares-Robles²,

Ruiz³

2018

Bringing Thermoelectricity Into Reality

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This chapter aims to analyse the performance of hybrid two-stage thermoelectric cooler systems [two-stage thermoelectric cooling devices (TEC)], which are composed of different thermoelectric materials in each stage with different leg geometric shapes. If we consider a temperature gradient inside a two-stage TEC, then, besides Joule heat, also Thomson heat has to be taken into account. We discuss the out-of-equilibrium thermodynamics equations of a one-dimensional model to provide the performance expressions that govern the system. TEC system performance is analysed in function of the Thomson coefficients ratio of both stages. We describe a recent geometric optimization procedure that includes leg geometry parameters such as ratio of cross-sectional area and length of legs for each stage of the two-stage TEC.

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Section: Optimization Analysis According To the Geometric Parameter Wmentioning

confidence: 99%

Thermoelectric Cooling: The Thomson Effect in Hybrid Two- Stage Thermoelectric Cooler Systems with Different Leg Geometric Shapes

Ruiz-Ortega¹,

Olivares-Robles²,

Ruiz³

2018

Bringing Thermoelectricity Into Reality

View full text Add to dashboard Cite

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“…The estimated market price for the material is 500 $/kg following Ref. [6]. The metric of evaluating performance per cost is COP divided by the product of volume, density, and unit price.…”

Section: Cost Factormentioning

confidence: 99%

“…We define the COP as a ratio of the amount of pumped heat over the injected electric power. A previous case-study of hotspot cooling on a uniformly heated chip [6] demonstrated the potential advantage in improving energy efficiency compared to a conventional TE cooler. In the study of a TE microcooler for hotspot cooling, cooling power is minimized to maintain the hotspot temperature, while the entire chip is attached to a microchannel heat sink for liquid-phase convection cooling.…”

Section: Introductionmentioning

confidence: 99%

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Performance and mass optimization of thermoelectric microcoolers

Koh

Yazawa

Shakouri

2015

International Journal of Thermal Sciences

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a b s t r a c tWe report a scalable and parametric analysis of thermoelectric (TE) microcoolers for hotspot cooling based on analytic formulations. Design for minimizing cooling power and least mass or cost of TE material is an ultimate goal for electronic devices that require spot cooling beyond that provided by passive heat transport to the thermal ground. Performance of thermoelectric hotspot cooling on electronic devices depends on external thermal resistances, physical dimension (thickness) of the thermoelectric element, and the applied drive current. Active cooling located at the hotspot minimizes the cooling power and the internal heat generation from the TE element and also minimizes the additional driving power used for heat rejection with a preexisting air-cooling fan or a liquid-cooling pump. Electronic devices are required to operate below a specific temperature for functionality and high reliability. The hotspot cooler must be designed to deal with the amount of heat generated from the heat source with this temperature constraint. We investigate two design cases: 1) the maximum cooling and 2) the minimum drive current for a given hotspot temperature to obtain an improved coefficient-ofperformance (COP). The study explores the impact of individual thermoelectric material properties, i.e. Seebeck coefficient, electrical conductivity, and thermal conductivity to find the direction that should be taken with engineered materials. We show that COP up to 8 is possible for hotspot heat fluxes of about 80 W/cm 2 , if TE leg thickness is optimized to~20e30 microns with today's Bi 2 Te 3 material. Model shows that COP > 2e3 is possible for hotspot heat fluxes bigger than 200e300 W/cm 2 . We find that lowering the thermal conductivity have the greatest impact, resulting in a thinner element (and therefore lower cost) while maintaining the same figure-of-merit (ZT).

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“…al. [8] had demonstrated the technique to grow similar μ-scale thermoelectric microcooler as the analytical model in the paper.…”

Section: Introductionmentioning

confidence: 99%

Cooling heat flux, COP, and cost optimization of integrated thermoelectric microcoolers with variation of thermoelectric properties

Koh

Yazawa

Shakouri

2014

Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)

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Thermoelectric (TE) microcoolers are solid state devices widely considered as strong candidates for precise temperature control and spot cooling in microelectronic circuits, especially for temperature sensitive devices such as laser diodes.Despite the excellent scalability and process compatibility of TE microcoolers for microelectronics, their utilization has been limited by their relatively moderate performance compared to vapor compression cycles due to the relatively small material figure-of-merit (ZT). In addition to a crucial advantage of TE for a hotspot cooling, improving the ZT value of thermoelectric material has been the focus of research interest over the past few decades. Yet the independent impacts of three components of the ZT value have not been very clear. In this paper, we report the material cost impact of TE microcooler integration and coefficient-ofperformance (COP) change relative to modifications of the electrical conductivity, the Seebeck coefficient, and the thermal conductivity. This study is mostly focused on high heat-flux spot cooling based on the analysis of a practical TE microcooler integrated with a microchannel heat sink.Based on a one-dimensional analytic model, including the system thermal resistances, we maximize the cooling COP as functions of the drive current and the design thickness of a TE element. An example demonstrates the cooling performance for a 500 μm x 500 μm size integrated circuit with a temperature constraint of 65 °C maximum and an operating temperature of 74 °C for the heat sink.Increasing the ZT value linearly increases the maximum COP for a given temperature constraint and the maximum COP changes equally by varying any of the thermoelectric properties as expected. For the same ZT value, however, a lower thermal conductivity requires a thinner TE element for a design optimized for COP, e.g. changing the thermal conductivity from 1.5 W/mK to 0.75 W/mK reduces the optimum thickness from approximately 9 μm to 5 μm for 100 W/cm² of heat flux. This result is encouraging for the utilization of TE for spot cooling since the TE cost directly relates to the mass usage of the material.KEY WORDS: thermoelectric, microcooler, energy efficiency, coefficient of performance, cooling heat flux, hot spot NOMENCLATUREA area, m 2 978-1-4799-5267-0/14/$31.00 ©2014 IEEE

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Cooling power optimization for hybrid solid-state and liquid cooling in integrated circuit chips with hotspots

Cited by 13 publications

References 9 publications

Thermoelectric Cooling: The Thomson Effect in Hybrid Two- Stage Thermoelectric Cooler Systems with Different Leg Geometric Shapes

Thermoelectric Cooling: The Thomson Effect in Hybrid Two- Stage Thermoelectric Cooler Systems with Different Leg Geometric Shapes

Performance and mass optimization of thermoelectric microcoolers

Cooling heat flux, COP, and cost optimization of integrated thermoelectric microcoolers with variation of thermoelectric properties

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