Impact of Interface Resistance on Pulsed Thermoelectric Cooling

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Y. Sungtaek Ju
Keyword(s):  
Heat Flux ◽  
Thermal Management ◽  
Thermoelectric Cooling ◽  
Infrared Sensors ◽  
New Techniques ◽  
Site Specific ◽  
Cooling Performance ◽  
Interface Resistance ◽  
High Pulse ◽  
The Impact

Pulsed thermoelectric cooling is an attractive approach for the site specific thermal management of infrared sensors and other low-heat flux devices. Intense Joule heating caused by electrical interface resistance, however, can severely degrade pulsed cooling performance. Numerical simulations are used to quantify the impact of the interface resistance on pulsed thermoelectric cooling. The degradation in performance is most pronounced for microcoolers that have small bulk resistivity at high pulse amplitudes. Our work also forms a basis for new techniques to probe interfaces in TE devices for energy harvesting as well as cooling applications.

Site-Specific and On-Demand High Heat-Flux Cooling Using Superlattice Based Thin-Film Thermoelectrics

2009 ◽  
Author(s):  
Ihtesham Chowdhury ◽  
Ravi Prasher ◽  
Kelly Lofgreen ◽  
Sridhar Narasimhan ◽  
Ravi Mahajan ◽  
...  
Keyword(s):  
Thin Film ◽  
Heat Flux ◽  
Thermal Management ◽  
High Performance ◽  
High Heat ◽  
Thermoelectric Device ◽  
High Heat Flux ◽  
General Will ◽  
Site Specific ◽  
Fully Integrated

We have recently reported the first ever demonstration of active cooling of hot-spots of >1 kW/cm2 in a packaged electronic chip using thin-film superlattice thermoelectric cooler (TEC) cooling technology [1]. In this paper, we provide a detailed account of both experimental and theoretical aspects of this technological demonstration and progress. We have achieved cooling of as much as 15°C at a location on the chip where the heat-flux is as high as ∼1300 W/cm2, with the help of a thin-film TEC integrated into the package. To our knowledge, this is the first demonstration of high heat-flux cooling with a thin-film thermoelectric device made from superlattices when it is fully integrated into a usable electronic package. Our results, which validate the concept of site-specific micro-scale cooling of electronics in general, will have significant potential for thermal management of future generations of microprocessors. Similar active thermal management could also be relevant for high-performance solid-state lasers and power electronic chips.

scholarly journals Spray Cooling With HFC-134a and HFO-1234yf for Thermal Management of Automotive Power Electronics

2015 ◽  
Author(s):  
Satvik J. Yaddanapudi ◽  
Huseyin Bostanci
Keyword(s):  
Heat Flux ◽  
Power Electronics ◽  
Thermal Management ◽  
Spray Cooling ◽  
Small Scale ◽  
Spray Characteristics ◽  
Flow Rates ◽  
Cooling Performance ◽  
Working Fluids ◽  
Hfc 134A

This study aimed to experimentally investigate the spray cooling characteristics for active two-phase cooling of automotive power electronics. Tests were conducted on a small-scale, closed loop spray cooling system featuring a pressure atomized spray nozzle. Two types of refrigerants, HFC-134a (R-134a) and HFO-1234yf, were selected as the working fluids. The test section (heater), made out of oxygen-free copper, had a 1-cm2 plain, smooth surface prepared following a consistent procedure, and served as a baseline case. Matching size thick film resistors, attached onto the copper heaters, generated heat and simulated high heat flux power electronics devices. The experiments were performed with saturated working fluids at room temperature level (22°C) by controlling the heat flux in increasing steps, and recording the corresponding steady-state temperatures to obtain cooling curves. Performance comparisons were made based on heat transfer coefficient (HTC) and critical heat flux (CHF) values. Effects of spray characteristics and liquid flow rates on the cooling performance were determined with three types of commercially available nozzles that generate full-cone sprays with fine droplets, and with varying flow rates between 1.6 to 5.4 ml/cm2.s. The experimental data showed that HFC-134a provided better performance compared to HFO-1234yf, in terms of HTC and CHF, which is believed to be dictated by the thermophysical properties that affect both the spray characteristics and heat acquisition ability. Overall, this study provided a framework for spray cooling performance with the current and next-generation refrigerants aimed for advanced thermal management of automotive power electronics.

Quantum-Well Si/SiC Self-Cooling for Thermal Management of High Heat Flux GaN HEMT Semiconductor Devices

2012 ◽  
Author(s):  
Peng Wang ◽  
Michael Manno ◽  
Avram Bar-Cohen
Keyword(s):  
Heat Flux ◽  
Quantum Well ◽  
Thermal Management ◽  
Hot Spot ◽  
Semiconductor Devices ◽  
High Heat ◽  
Wide Bandgap ◽  
High Heat Flux ◽  
High Electron ◽  
The Impact

Wide bandgap semiconductor technology is expected to have a dramatic impact on radar and communications systems. To take full advantage of the power capabilities and small device sizes of wide bandgap semiconductors, new and novel thermal management solutions, especially for high power density, monolithic microwave integrated circuits (MMICs) are in high demand. In this paper, a quantum-well Si/SiC self-cooling concept for hot spot thermal management at the multi-fingered GaN high electron mobility transistor (HEMTs) in the GaN-on-SiC package is proposed and investigated using a three dimensional (3-D) thermal-electric coupling simulation. The impact of electric current, cooler size, Si/SiC substrate thickness, Si/SiC thermal conductivity, and interfacial parasitic effect on the hot spot cooling is examined and discussed. The preliminary modeling results strongly suggest that self-cooling phenomenon inherent in the quantum-well Si/SiC substrate can be used to remove local high heat flux hot spot on the semiconductor devices.

Numerical Simulation of Flow Boiling in Micro Channel to Study Bubble Dynamics

2019 ◽  
Author(s):  
Uday Kumar Alugoju ◽  
Satish Kumar Dubey ◽  
Arshad Javed
Keyword(s):  
Heat Flux ◽  
Thermal Management ◽  
Heat Sink ◽  
Bubble Dynamics ◽  
Flow Boiling ◽  
Heat Fluxes ◽  
Clear Understanding ◽  
Microchannel Heat Sink ◽  
Micro Channel ◽  
The Impact

Abstract With the recent developments in miniaturization techniques of electronic chips, the power density of these chips has risen drastically. Available thermal management technologies like air cooled heat sink and liquid cooled heat sink are unable to keep up with the demand. However, thermal management technologies using flow boiling in microchannel heat sink can dissipate higher heat fluxes. Flow boiling technologies in micro channel heat sinks are not commercially established due to issues such as reliability, flow reversal, dry out, critical heat flux, limited knowledge of bubble dynamics, correlations, etc. In this study, performance of flow boiling in a diverging microchannel with uniform heat flux condition has been investigated. Simulations have been performed on ANSYS Fluent using Volume of Fluid (VOF). VOF is used to track the interface between different phases. The impact of angle on the bubble dynamics of the coolant and flow patterns has been studied. The simulated numerical results are compiled and presented. The results provide a clear understanding of the impact of angle on the bubble dynamics in flow boiling microchannel heat sink.

An Experimental and Computational Parametric Investigation of Flow Conditions in Intersecting Circular Passages

2007 ◽  
Author(s):  
Scott R. Nowlin ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Eduardo Romero ◽  
Mark Mitchell
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Cooling System ◽  
Industrial Applications ◽  
Loss Coefficient ◽  
Scale Model ◽  
Order Estimate ◽  
Flow Conditions ◽  
Cooling Performance ◽  
The Impact

In some industrial applications such as turbine airfoil film cooling, coolant passage configurations must maintain sufficient pressure margin to prevent hot gas ingestion whilst using holes of large enough diameter to avoid foreign object blockage. This frequently means that some regions of a film-cooled surface are provided with excess air, or that exhausting film jets are over-blown, adversely amplifying local mixing or coolant separation and therefore enhancing heat flux. A cooling system featuring intersecting passages would allow a high pressure margin to be obtained using discrete, localized loss mechanisms where flows intersect. The degree of loss could be tailored to the local internal and external flow conditions by altering the intersection extent (i.e. the degree of intersecting passage offset), thereby optimizing the use of coolant. Furthermore, localized in-passage convective heat transfer enhancements caused by thin boundary layers and impinging flows in the vicinity of the intersections would improve total heat flux (Watts per square meter) despite surface area lost to intersection voids. As the heat transfer and loss enhancements do not rely on intricately manufactured flow features, the cooling performance is likely to be robust in industrial applications, extending component life. An experimental and computational investigation of the flow through two intersecting cylindrical pipes has been carried out at turbine engine-representative conditions to test these hypotheses. While previous workers have characterized loss and heat transfer in co-planar intersecting holes, this first-of-a-kind study parametrically investigates both fully and partially-intersecting passages, accounting for passage offsets due to typical manufacturing tolerances or purpose-built localized loss enhancements. The loss coefficient across the intersection has been experimentally determined for a range of intersection angles and degrees of intersection in a large scale model running at near atmospheric conditions. The results are used to develop an empirical correlation for the loss coefficient for the isolated intersecting circular channel. A commercial computational fluid dynamics (CFD) code, FLUENT©, has been used to model heat transfer locally within selected intersecting geometries, and thus to examine the average heat transfer coefficient compared to that predicted by the well-known Dittus-Boelter correlation and other investigators. Insight gained from the CFD predictions enables a first-order estimate of the impact of adding intersections to the convective cooling performance of these advanced cooling configurations. Results show that even an imperfectly machined (i.e. partial) intersection can provide a significant improvement to heat transfer as well as enhanced loss.

The Impact of Bioconjugation on the Interfacial Activity of a Protein Biosurfactant

2018 ◽  
Author(s):  
Hossam H Tayeb ◽  
Marina Stienecker ◽  
Anton Middelberg ◽  
Frank Sainsbury
Keyword(s):  
Polyethylene Glycol ◽  
Colloidal Stability ◽  
Point Mutations ◽  
Pharmaceutical Formulations ◽  
Industrial Processes ◽  
Parent Molecule ◽  
Site Specific ◽  
Interfacial Activity ◽  
Surface Active ◽  
The Impact

Biosurfactants, are surface active molecules that can be produced by renewable, industrially scalable biologic processes. DAMP4, a designer biosurfactant, enables the modification of interfaces via genetic or chemical fusion to functional moieties. However, bioconjugation of addressable amines introduces heterogeneity that limits the precision of functionalization as well as the resolution of interfacial characterization. Here we designed DAMP4 variants with cysteine point mutations to allow for site-specific bioconjugation. The DAMP4 variants were shown to retain the structural stability and interfacial activity characteristic of the parent molecule, while permitting efficient and specific conjugation of polyethylene glycol (PEG). PEGylation results in a considerable reduction on the interfacial activity of both single and double mutants. Comparison of conjugates with one or two conjugation sites shows that both the number of conjugates as well as the mass of conjugated material impacts the interfacial activity of DAMP4. As a result, the ability of DAMP4 variants with multiple PEG conjugates to impart colloidal stability on peptide-stabilized emulsions is reduced. We suggest that this is due to constraints on the structure of amphiphilic helices at the interface. Specific and efficient bioconjugation permits the exploration and investigation of the interfacial properties of designer protein biosurfactants with molecular precision. Our findings should therefore inform the design and modification of biosurfactants for their increasing use in industrial processes, and nutritional and pharmaceutical formulations.

scholarly journals Imaging with Coherent X-rays: From the Early Synchrotron Tests to SYNAPSE

2021 ◽  
Vol 7 (8) ◽  
pp. 132
Author(s):  
Giorgio Margaritondo ◽  
Yeukuang Hwu
Keyword(s):  
Human Brain ◽  
International Collaboration ◽  
Phase Contrast ◽  
Asia Pacific ◽  
X Rays ◽  
New Techniques ◽  
Simple Description ◽  
Contrast Radiography ◽  
The Impact ◽  
Extract Information

The high longitudinal and lateral coherence of synchrotron X-rays sources radically transformed radiography. Before them, the image contrast was almost only based on absorption. Coherent synchrotron sources transformed radiography into a multi-faceted tool that can extract information also from “phase” effects. Here, we report a very simple description of the new techniques, presenting them to potential new users without requiring a sophisticated background in advanced physics. We then illustrate the impact of such techniques with a number of examples. Finally, we present the international collaboration SYNAPSE (Synchrotrons for Neuroscience—an Asia-Pacific Strategic Enterprise), which targets the use of phase-contrast radiography to map one full human brain in a few years.

scholarly journals Site-specific N-glycosylation analysis of animal cell culture-derived Zika virus proteins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander Pralow ◽  
Alexander Nikolay ◽  
Arnaud Leon ◽  
Yvonne Genzel ◽  
Erdmann Rapp ◽  
...  
Keyword(s):  
Zika Virus ◽  
Animal Cell ◽  
Gradient Centrifugation ◽  
Viral Envelope ◽  
Protein Glycosylation ◽  
High Yield ◽  
Structural Protein ◽  
Site Specific ◽  
E Protein ◽  
The Impact

AbstractHere, we present for the first time, a site-specific N-glycosylation analysis of proteins from a Brazilian Zika virus (ZIKV) strain. The virus was propagated with high yield in an embryo-derived stem cell line (EB66, Valneva SE), and concentrated by g-force step-gradient centrifugation. Subsequently, the sample was proteolytically digested with different enzymes, measured via a LC–MS/MS-based workflow, and analyzed in a semi-automated way using the in-house developed glyXtoolMS software. The viral non-structural protein 1 (NS1) was glycosylated exclusively with high-mannose structures on both potential N-glycosylation sites. In case of the viral envelope (E) protein, no specific N-glycans could be identified with this method. Nevertheless, N-glycosylation could be proved by enzymatic de-N-glycosylation with PNGase F, resulting in a strong MS-signal of the former glycopeptide with deamidated asparagine at the potential N-glycosylation site N444. This confirmed that this site of the ZIKV E protein is highly N-glycosylated but with very high micro-heterogeneity. Our study clearly demonstrates the progress made towards site-specific N-glycosylation analysis of viral proteins, i.e. for Brazilian ZIKV. It allows to better characterize viral isolates, and to monitor glycosylation of major antigens. The method established can be applied for detailed studies regarding the impact of protein glycosylation on antigenicity and human pathogenicity of many viruses including influenza virus, HIV and corona virus.

Sign in / Sign up

Export Citation Format

Share Document