Evaporative Microchannel Cooling: An Atomistic Approach

2010 ◽  
Author(s):  
A. J. H. Frijns ◽  
E. A. T. van den Akker ◽  
P. A. J. Hilbers ◽  
P. Stephan ◽  
A. A. van Steenhoven
Keyword(s):  
Molecular Model ◽  
Electronic Devices ◽  
Technical Problem ◽  
Md Simulations ◽  
Promising Technique ◽  
Temperature Jumps ◽  
Overall Performance ◽  
Microchannel Cooling ◽  
Physical Phenomena ◽  
The Continuum

Heat generation and temperature rise in electronic devices is a technical problem with increasing importance, since the number of transistors per surface area on integrated circuitries is rapidly increasing. If the heat cannot effectively be carried away damage in the circuitry may occur. Therefore enhanced and integrated cooling is needed. A promising technique is evaporative microchannel cooling. However, a major problem in modeling such micro-device is that the continuum approach starts to fail in the vapor phase and more detailed modeling becomes necessary. Since on these small scales the boundary and interface conditions are very important for the overall performance of the device, we choose the approach in which we start with understanding the essential physical phenomena at a molecular level. In this paper a detailed particle-based model is derived for these interactions: local interactions between the three phases are studied by molecular dynamics (MD) simulations in a detailed way. In this way physically and thermodynamically correct interface and boundary conditions (e.g. slip velocities and temperature jumps) are ensured. Finally, the enhanced heat transfer in the evaporative zone (Argon on a Calcium surface) is simulated by our molecular model and is compared to the results obtained by the continuum microregion model developed by P. Stephan et al. (Int. J. Heat Mass Transfer, 35, pp. 383–391, 1992).

Focused Ion Beam Irradiation Induced Damages on CMOS and Bipolar Technologies

1998 ◽  
Author(s):  
J. Benbrik ◽  
G. Rolland ◽  
P. Perdu ◽  
B. Benteo ◽  
M. Casari ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Electronic Devices ◽  
Complete Characterization ◽  
Bipolar Transistors ◽  
Ion Beam Irradiation ◽  
Physical Mechanisms ◽  
Dc Characteristics ◽  
Electrical Degradation ◽  
Physical Phenomena

Abstract Focused Ion Beam is commonly used for IC repairs and modifications. However, FIB operation may also induce a damaging impact which can takes place far from the working area due to the charge-up phenomenon. A complete characterization joined to an in-depth understanding of the physical phenomena arising from FIB irradiation is therefore necessary to take into account spurious FIB induced effects and to enhance the success of FIB modifications. In this paper, we present the effects of FIB irradiation on the electrical DC performances of different electronic devices such as nMOS and pMOS transistors, CMOS inverters, PN junctions and bipolar transistors. From the observed behavior of the DC characteristics evolution of the devices, some suggestions about physical mechanisms inducing the electrical degradation are proposed.

scholarly journals A Molecular Model of PEMFC Catalyst Layer: Simulation on Reactant Transport and Thermal Conduction

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 148
Author(s):  
Wenkai Wang ◽  
Zhiguo Qu ◽  
Xueliang Wang ◽  
Jianfei Zhang
Keyword(s):  
Thermal Conductivity ◽  
Proton Exchange Membrane ◽  
Molecular Model ◽  
Phase Interface ◽  
Catalyst Layer ◽  
Md Simulations ◽  
Distribution Functions ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Reaction Efficiency

Minimizing platinum (Pt) loading while reserving high reaction efficiency in the catalyst layer (CL) has been confirmed as one of the key issues in improving the performance and application of proton exchange membrane fuel cells (PEMFCs). To enhance the reaction efficiency of Pt catalyst in CL, the interfacial interactions in the three-phase interface, i.e., carbon, Pt, and ionomer should be first clarified. In this study, a molecular model containing carbon, Pt, and ionomer compositions is built and the radial distribution functions (RDFs), diffusion coefficient, water cluster morphology, and thermal conductivity are investigated after the equilibrium molecular dynamics (MD) and nonequilibrium MD simulations. The results indicate that increasing water content improves water aggregation and cluster interconnection, both of which benefit the transport of oxygen and proton in the CL. The growing amount of ionomer promotes proton transport but generates additional resistance to oxygen. Both the increase of water and ionomer improve the thermal conductivity of the C. The above-mentioned findings are expected to help design catalyst layers with optimized Pt content and enhanced reaction efficiency, and further improve the performance of PEMFCs.

Power Withstanding Capability and Transient Temperature of Carbon Nanotube-Based Nano Electrical Interconnects

2021 ◽  
Author(s):  
Femi Robert
Keyword(s):  
Carbon Nanotube ◽  
Transient Analysis ◽  
Electronic Devices ◽  
Transient Temperature ◽  
Nanoelectronic Devices ◽  
Cu Interconnects ◽  
Electrical Interconnects ◽  
Steady State Temperature ◽  
The Given ◽  
The Continuum

Abstract This paper exhibits the electrothermal modelling and evaluation of Carbon Nanotube (CNT) based electrical interconnects for electronic devices. The continuum model of the CNT is considered and the temperature across interconnect is predicted for the given power. Finite element modelling software COMSOL Multiphysics is used to carry out the simulations. The results are compared with Al and Cu interconnects. An electrothermal analysis is also carried out to obtain the temperature for the given power for Single-Walled CNT, Double-Walled CNT, Triple-Walled CNT, and Multi-Walled CNT. Results show that the CNT interconnects performs better when compared to Al and Cu interconnects. The power withstanding capability of CNT is 68.75 times more than Al and 32.35 times more than Cu. Based on the transient analysis, the time taken by the CNT interconnects to reach a steady temperature is obtained as 0.007 ns. On the application of power, Cu and Al interconnects takes 0.1 ns to reach the steady-state temperature. The nanostructured CNT based electrical interconnects would play a considerable role in replacing Cu and Al electrical interconnect applications for micro and nanoelectronic devices.

Experimental Investigation of Boiling Heat Transfer in a Liquid Chamber With Partially Soluble Nanofluids

2021 ◽  
Author(s):  
Noriyuki Unno ◽  
Kazuhisa Yuki ◽  
Risako Kibushi ◽  
Rika Nogita ◽  
Atsuyuki Mitani
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Electronic Devices ◽  
High Heat ◽  
Experimental Result ◽  
High Heat Flux ◽  
Promising Technique ◽  
Cooling Device ◽  
Cooling Devices

Abstract Boiling heat transfer (BHT) is a promising technique to remove a high heat flux emitted from next-generation electronic devices. However, critical heat flux (CHF) is a big problem in BHT because it restricts the maximum performance of the cooling devices using BHT. Nanofluid has been widely used to improve the CHF. In this study, the authors investigated the BHT of a compact cooling device at low pressure using a special nanofluid: that is made with partially soluble particles in water. The experimental result found that the CHF with the special nanofluid is 170 W/cm2 and is higher than that with nanofluid made with an insoluble nanoparticle.

A Molecular Model of Asperity Contact and Comparison to Continuum Based Models

2008 ◽  
Author(s):  
Wei Huang ◽  
Robert L. Jackson
Keyword(s):  
Contact Mechanics ◽  
Continuum Mechanics ◽  
Material Properties ◽  
Molecular Model ◽  
Small Scale ◽  
Elastic Contact ◽  
Asperity Contact ◽  
Molecular Forces ◽  
The Continuum

Surface asperities can range widely in size. Therefore it is important to characterize the effect of size and scale on the contact mechanics. This work presents a molecular model of asperity contact in order to characterize small scale asperity contact. The model is also compared to existing continuum mechanics based models developed originally by Hertz for elastic contact and later expanded by others to include plasticity. It appears that the predictions can be related to each other and that the continuum material properties can be related to the properties describing the molecular forces.

Atomically Informed Continuum Models for the Elastic Contact Properties of Hollow and Coated Rigid Cylinders at the Nanoscale

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Leon Gorelik ◽  
Dan Mordehai
Keyword(s):  
Contact Stiffness ◽  
Md Simulations ◽  
Atomic Scale ◽  
Continuum Models ◽  
Elastic Contact ◽  
Pressure Profiles ◽  
Hollow Cylinders ◽  
Coated Surfaces ◽  
The One ◽  
The Continuum

Understanding the mechanical properties of contacts at the nanoscale is key to controlling the strength of coated surfaces. In this work, we explore to which extent existing continuum models describing elastic contacts with coated surfaces can be extended to the nanoscale. Molecular dynamics (MD) simulations of hollow cylinders or coated rigid cylinders under compression are performed and compared with models at the continuum level, as two representative extreme cases of coating which is substantially harder or softer than the substrate, respectively. We show here that the geometry of the atomic-scale contact is essential to capture the contact stiffness, especially for hollow cylinders with high relative thicknesses and for coated rigid cylinders. The contact pressure profiles in atomic-scale contacts are substantially different than the one proposed in the continuum models for rounded contacts. On the basis of these results, we formulate models whose solution can be computed analytically for the contact stiffness in the two extreme cases, and show how to bridge between the atomic and continuum scales with atomically informed geometry of the contact.

The Effect of Temperature on Defect Production by Displacement Cascades in alpha;-IRON

1996 ◽  
Vol 439 ◽  
Author(s):  
F. Gao ◽  
D. J. Bacon ◽  
P. E. J. Flewitt ◽  
T. A. Lewis
Keyword(s):  
Molecular Dynamics ◽  
Md Simulations ◽  
Irradiation Temperature ◽  
Effect Of Temperature ◽  
Cascade Process ◽  
Thermal Spike ◽  
Defect Production ◽  
Alpha Iron ◽  
Displacement Cascades ◽  
The Continuum

AbstractMolecular dynamics (MD) simulations have been used to study the number and arrangement of defects produced by displacement cascades as functions of irradiation temperature, Tirr, in α-iron. The continuum treatment of heat conduction was used to adjust the temperature of the MD boundary atoms throughout the cascade process. This new hybrid model has been applied to cascades of either 2 or 5 keV at 100K, 400K, 600K and 900K. The number of Frenkel pairs decreases by about 20–30% as Tir increases from 100K to 900K, due to the increase in the lifetime of the thermal-spike phase. The same effect also brings about an increase in the proportion of selfinterstitial atoms that form clusters.

scholarly journals Molecular continua for polymeric liquids in large-amplitude oscillatory shear flow

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840036 ◽  
Author(s):  
A. Jeffrey Giacomin ◽  
Chaimongkol Saengow
Keyword(s):  
Large Amplitude ◽  
Molecular Model ◽  
Orientation Distribution ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Polymeric Liquid ◽  
Oscillatory Shear Flow ◽  
Continuum Description ◽  
Specific Material ◽  
The Continuum

In this paper, we connect a molecular description of the rheology of a polymeric liquid to a continuum description, and then test this connection for large-amplitude oscillatory shear (LAOS) flow. Specifically, for the continuum description, we use the 6-constant Oldroyd framework, and for the molecular, we use the simplest relevant molecular model, the suspension of rigid dumbbells. By relevant, we mean predicting at least higher harmonics in the shear stress response in LAOS. We call this connection a molecular continuum, and we examine two ways of arriving at this connection. The first goes through the retarded motion expansion, and the second expands each of a set of specific material functions (complex, steady shear, and steady uniaxial extensional viscosities). Both ways involve in comparing the coefficients of expansions and then solve for the six constants of the continuum framework in terms of the two constants of the rigid dumbbell suspension. The purpose of a molecular continuum is that many well-known results for rigid dumbbell suspensions in other flow fields can also be easily obtained, without having to firstly find the orientation distribution function. In this paper, we focus on the recent result for the rigid dumbbell suspension in LAOS. We compare the accuracies of the retarded motion molecular continuum (RMMC) with the material function molecular continuum (MFMC). We find the RMMC to be the most accurate for LAOS.

Cooling of Microelectronic Devices Packaged in a Single Chip Module Using Single Phase Refrigerant R-123

2009 ◽  
Author(s):  
Tushara Pasupuleti ◽  
Satish G. Kandlikar
Keyword(s):  
Single Phase ◽  
Cooling System ◽  
Electronic Devices ◽  
Working Fluid ◽  
Practical Application ◽  
Microelectronic Device ◽  
Single Chip ◽  
Microelectronic Devices ◽  
Cooling Devices ◽  
Microchannel Cooling

An approach towards practical application of microchannel cooling system is necessary as the demand of high power density devices is increasing. Colgan et. al. [1] have designed a unit known as Single Chip Module (SCM) by considering the practical issues for packaging a microchannel cooling system with a microelectronic device. The performance of the SCM has already been investigated by using water as working fluid by Colgan et. al. [1]. Considering the actual working conditions, water cannot be used in electronic devices as the working fluid because any leakage may lead to system damage. Alternative fluids like refrigerants were considered. In this research, the performance of SCM has been studied by using refrigerant R-123 as working fluid and compared with water cooled system. Cooling of 83.33 W/cm2 has been achieved for a powered area of 3 cm2 by maintaining chip temperature of 60°C. The heat transfer co-efficient obtained at a flowrate of 0.7 lpm was 34.87 kW/m2-K. The results obtained indicate that from a thermal viewpoint, R-123 can be considered as working fluid for microelectronic cooling devices.

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