There is a significant need for site-specific and on-demand cooling in electronic, optoelectronic and bioanalytical devices, where cooling is currently achieved by the use of bulky and/or over-designed system-level solutions. Thermoelectric devices can address these limitations while also enabling energy-efficient solutions, and significant progress has been made in the development of nanostructured thermoelectric materials with enhanced figures-of-merit. However, fully functional practical thermoelectric coolers have not been made from these nanomaterials due to the enormous difficulties in integrating nanoscale materials into microscale devices and packaged macroscale systems. Here, we show the integration of thermoelectric coolers fabricated from nanostructured Bi2Te3-based thin-film superlattices into state-of-the-art electronic packages. We report cooling of as much as 15 degrees C at the targeted region on a silicon chip with a high ( approximately 1,300 W cm-2) heat flux. This is the first demonstration of viable chip-scale refrigeration technology and has the potential to enable a wide range of currently thermally limited applications.

On-chip cooling by superlattice-based thin-film thermoelectrics

Solid-state electronics

Thermoelectric (TE) technology is regarded as alternative and environmentally friendly technology for harvesting and recovering heat which is directly converted into electrical energy using thermoelectric generators (TEG). Conversely, Peltier coolers and heaters are utilized to convert electrical energy into heat energy for cooling and heating purposes The main challenge lying behind the TE technology is the low efficiency of these devices mainly due to low figure of merit (ZT) of the materials used in making them as well as improper setting of the TE systems. The objective of this work is to carry out a comprehensive review of TE technology encompassing the materials, applications, modelling techniques and performance improvement. The paper has covered a wide range of topics related to TE technology subject area including the output power conditioning techniques. The review reveals some important critical aspects regarding TE device application and performance improvement. It is observed that the intensified research into TE technology has led to an outstanding increase in ZT, rendering the use TE devices in diversified application a reality. Not only does the TE material research and TE device geometrical adjustment contributed to TE device performance improvement, but also the use of advanced TE mathematical models which have facilitated appropriate segmentation TE modules using different materials and design of integrated TE devices. TE devices are observed to have booming applications in cooling, heating, electric power generation as well as hybrid applications. With the generation of electric energy using TEG, not only does the waste heat provide heat source but also other energy sources like solar, geothermal, biomass, infra-red radiation have gained increased utilization in TE based systems. However, the main challenge remains in striking the balance between the conflicting parameters; ZT and power factor, when designing and optimizing advanced TE materials. Hence more research is necessary to overcome this and other challenge so that the performance TE device can be improved further.

/pdf/a-comprehensive-review-of-thermoelectric-technology-2zghp2rn7k.pdf

A comprehensive review of thermoelectric technology: materials, applications, modelling and performance improvement

https://bura.brunel.ac.uk/bitstream/2438/14115/5/Fulltext.pdf

Flow boiling in microchannels: Fundamentals and applications

Thermal management and temperature uniformity enhancement of electronic devices by micro heat sinks: A review

Thermal management of microprocessors has become an increasing challenge in recent years because of localized high flux hotspots which can not be effectively removed by conventional cooling techniques. This paper describes the novel use of the silicon chip itself as thermoelectric microcooler to suppress the hotspot temperature. A three-dimensional analytical thermal model of the silicon chip, including localized silicon thermoelectric cooling, thermoelectric heating, Joule heating, hotspot heating, background heating, and conductive/convective cooling on the back of the silicon chip, is developed and used to predict the on-chip hotspot cooling performance. The effects of chip thickness, microcooler size, doping concentration and parasitic Joule heating from the electric contact resistance on hotspot cooling are investigated in details.Copyright © 2006 by ASME

Analytical Modeling of On-Chip Hotspot Cooling Using Silicon Thermoelectric Microcoolers

This paper investigates the potential application of an R134a-cooled two-phase micro/mini-cooler for thermal management of a triple junction solar cell under 2000 suns concentration An analytical model for the triple-junction solar cell temperature based on prediction of two-phase flow boiling in mini/microchannel coolers is developed and exercised with empirical correlations from the open literature for the heat transfer coefficient, pressure drop, and critical heat flux The thermofluid analysis is augmented by detailed energy modeling, using two uniquely defined coefficient of performance metrics — COP relating the solar energy harvest to pumping power consumption and COPT relating the solar energy harvest to the “parasitic” work expended to provide the requisite cooling, including pumping power and the energy consumed in the formation and fabrication of the microcooler itself Three constant fin thicknesses of 100μm, 300μm and 500μm are examined for a range of R134a flow rates and geometries to determine the energy efficient design for a 10mm×10mm triple junction CPV cell The results reveal that two-phase cooling of CPV’s can achieve very high COPT values, substantially exceeding 104 for much of the design space of interest, though the energy efficiency is dependent on microcooler geometry and the number or pitch of the microcooler channelsCopyright © 2012 by ASME

Energy Efficient Two-Phase Micro-Cooler Design for a Concentrated Photovoltaic Triple Junction Cell

Proposed uses of solid-state thermoelectric micro- coolers for hot spot remediation have included the formation of a superlattice layer on the back of the microprocessor chip, but there have been few studies on the cooling perfor- mance of such devices. This paper provides the results of 3-D, electrothermal, finite element modeling of a superlattice micro- cooler, focusing on the hot spot temperature and superlattice surface temperature reductions, respectively. Simulated temper- ature distributions and heat flow patterns in the silicon, associated with variations in microcooler geometry, chip thickness, hot spot size, hot spot heat flux, and superlattice thickness are provided. Comparison is made to hot spot cooling achieved by the Peltier effect in the silicon microprocessor chip itself. The numerical results suggest that, for a variety of operating conditions and geometries, while increasing the superlattice thickness serves to decrease the exposed superlattice surface temperature, it is ineffective in reducing the hot spot temperature below that due to the silicon Peltier effect.

Superlattice µTEC Hot Spot Cooling

Thermoelectric cooling has been well documented as a solution for hotspots in electronic devices. Hotspots arise from the heterogeneous power dissipation of most computer chips and power electronics. This paper reviews the recent progress in thermoelectric self-cooling and goes on to study the transient behavior of a germanium thermoelectric self-cooler. A 3-D thermoelectric simulation is used to explore the effects of various initial conditions, current pulse durations, current pulse magnitudes, and die thicknesses. Additionally, a new cooling metric is introduced in order to more effectively characterize the advantage of transient cooling. The results suggest that transient thermoelectric cooling has the potential to improve hotspot temperature reduction by approximately 30% relative to what is achievable in steady state operation.

Peng Wang

Papers

Analytical Modeling of On-Chip Hotspot Cooling Using Silicon Thermoelectric Microcoolers

Energy Efficient Two-Phase Micro-Cooler Design for a Concentrated Photovoltaic Triple Junction Cell

Superlattice µTEC Hot Spot Cooling

Transient thermoelectric self-cooling of a germanium hotspot

Corrections to "Mini-contact enhanced thermoelectric cooling of hot spots in high power devices"