Modeling and Simulation Challenges in Embedded Two Phase Cooling: DARPA’s ICECool Program

2015 ◽  
Author(s):  
Kaiser Matin ◽  
Avram Bar-Cohen ◽  
Joseph J. Maurer
Keyword(s):  
Heat Transfer ◽  
Modeling And Simulation ◽  
Coefficient Of Thermal Expansion ◽  
Operating Conditions ◽  
Electrical Performance ◽  
Two Phase ◽  
Modeling Tools ◽  
Analysis And Design ◽  
System Pressure ◽  
The Impact

Modeling and simulation of two-phase phenomena, as well as their impact on electrical performance and physical integrity are critical to the success of embedded cooling strategies. In DARPA’s Intrachip/Interchip Embedded Cooling (ICECool) program, thermal/electrical/mechanical co-simulation and modeling tools are being applied to the analysis and design of RF GaN MMIC (Monolithic Microwave Integrated Circuit) Power Amplifiers (PA) and digital ICs, with the ultimate goal of achieving greater than 3X electronic performance improvement. This paper addresses various simulation strategies and numerical techniques adopted by the DARPA ICECool performers, with attention devoted to co-simulation through coupled iterations of thermal, mechanical and electrical behavior for capturing device characteristics and predicting reliability and “best in class” simulations that can provide an understanding of device behavior during rugged operating conditions impacted by multi-physics environments. The effect of CTE (Coefficient of Thermal Expansion) mismatch on bond and structural integrity, the impact of cooling fluid choice on performance, the factors affecting erosion/corrosion in the microchannels, as well as electro-migration limits and joule heating effects, will also be addressed. A separate discussion of various two-phase issues, including interface tracking, system pressure drops, conjugate heat transfer, estimating near wall heat transfer coefficients, and predicting CHF (Critical Heat Flux) and dryout is also provided.

scholarly journals Thermal and Chemical Integrity of Ru Electrode in Cu/TaOx/Ru ReRAM Memory Cell

2019 ◽  
Vol 8 (12) ◽  
pp. N220-N233
Author(s):  
Mohammad Al-Mamun ◽  
Sean W. King ◽  
Marius Orlowski
Keyword(s):  
Memory Cell ◽  
Operating Conditions ◽  
Electrical Performance ◽  
Pt Electrode ◽  
Switching Performance ◽  
Inert Electrode ◽  
Work Function Difference ◽  
The Impact ◽  
Si Wafer

A good candidate for replacing the inert platinum (Pt) electrode in the well-behaved Cu/TaOx/Pt resistive RAM memory cell is ruthenium (Ru), already successfully deployed in the CMOS back end of line. We benchmark Cu/TaOx/Ru device against Cu/TaOx/Pt and investigate the impact of embedment of Cu/TaOx/Ru on two different substrates, Ti(20nm)/SiO2(730nm)/Si and Ti(20nm)/TaOx(30nm)/SiO2(730nm)/Si, on the cell's electrical performance. While the devices show similar switching performance at some operating conditions, there are notable differences at other operation regimes shedding light on the basic switching mechanisms and the role of the inert electrode. The critical switching voltages are significantly higher for Ru than for Pt devices and can be partly explained by the work function difference and different surface roughness of the inert electrode. The poorer switching properties of the Ru device are attributed to the degraded inertness properties of the Ru electrode as a stopping barrier for Cu+ ions as compared to the Pt electrode. However, some of the degraded electrical properties of the Ru devices can be mitigated by an improved integration of the device on the Si wafer. This improvement is attributed to the suppression of crystallization of Ru and its silicidation reactions that take place at elevated local temperatures, present mainly during the reset operation. This hypothesis has been corroborated by extensive XRD studies of multiple layer systems annealed at temperatures between 300K and 1173K.

A comprehensive review on the impact of nanofluid in solar photovoltaic/thermal system

2021 ◽  
pp. 095440622110556
Author(s):  
E Manikandan ◽  
K Mayandi ◽  
M Sivasubramanian ◽  
N Rajini ◽  
S Rajesh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Energy Resource ◽  
Green Energy ◽  
Electrical Performance ◽  
Solar Photovoltaic ◽  
Solar Pv ◽  
The Impact ◽  
Thermo Physical Properties ◽  
T System

Solar energy is a major renewable energy resource used in power production, heating processes, and other applications such as domestic and industrial utilization. It is an abundant form of green energy. Different techniques have been made for energy conversion and one among them is solar photovoltaic/thermal (PV/T) system. Unfortunately, the greatest cause of concern is the rise in temperature of solar PV cells, which will have a negative effect on electrical performance. Thereby, eliminating excess heat on PV cells with heat transfer fluids to lower the temperature of the cells can improve electrical efficiency. A nanofluid is a promising heat transfer fluid to effectively enhance the system efficacy compared with conventional fluids. As the nanoparticle size is very small, the surface area of the nanoparticle is large so it enhances the heat transfer rate. Thereby, recently it has taken on a new dimension for research studies to enhance its thermal behavior for engineering application. This review paper discusses about the importance of nanofluid in solar PV/T system and advantages of employing nanofluid in PV/T system which has high thermo-physical properties. Nanoparticle and nanofluid preparation methods were presented. The thermo-physical properties like thermal conductivity, viscosity, density, and specific heat capacity were also discussed.

Numerical and experimental investigation on the effect of the two-phase flow pattern on heat transfer of piston cooling gallery

2019 ◽  
Vol 20 (5) ◽  
pp. 507 ◽  
Author(s):  
Lijun Deng ◽  
Jian Zhang ◽  
Guannan Hao ◽  
Jing Liu
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Unstable Wave ◽  
Fluid Viscosity ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Process ◽  
The Impact ◽  
Piston Cooling

To study factors affecting the formation and conversion of two-phase flow pattern as well as the heat transfer of piston cooling gallery, a transient visual target test bench was set up to research the oscillatory flow characteristics in the cooling gallery under idle condition of the engine. The computational fluid dynamics (CFD) was employed while dynamic mesh technology, SST k–ω turbulence model and volume of fluid (VOF) two-phase flow model were applied to simulate the flow process of piston cooling gallery so as to predict the distribution pattern of two-phase flow. Simulation results were in good agreement with that experimentally obtained. It was observed that in the reciprocating movement of the piston, the action of two-phase flow oscillation was severe, forming some unstable wave flows and slug flows. Results show that under the same pipe diameter, the increase of fluid viscosity results in the decrease of amplitude and the increase of the liquid slugs number as well as the enhancement on heat transfer effect. In addition, it was revealed that injection pressure has little effect on the two-phase flow pattern. However, when the pressure is reduced, the change of the liquid phase is weakened and the locations of flow pattern transition move towards to the behind, thus the impact on the heat transfer is also faint.

Thermal–Hydraulic Performance Analysis of a Convergent Double Pipe Heat Exchanger

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ahmed T. Al-Sammarraie ◽  
Kambiz Vafai
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Hydraulic Performance ◽  
Operating Conditions ◽  
Contraction Ratio ◽  
Wide Range ◽  
Prandtl Numbers ◽  
Double Pipe ◽  
The Impact ◽  
Pipe Heat

The present investigation proposes an innovative convergent double pipe heat exchanger (C-DPHE). A two-dimensional (2D) axisymmetric heat transfer model with counterflow is employed to analyze the thermal and hydraulic performance of this configuration numerically. The impact of convergence in the flow direction, using a wide range of contraction ratio (Cr), is explored. The effect of Reynolds and Prandtl numbers on the flow and heat transfer is addressed, as well. The model results were validated with available data from the literature, and an excellent agreement has been confirmed. In general, the findings of the present study indicate that increasing the contraction ratio increases heat transfer and pressure drop in the C-DPHE. Moreover, this configuration has a prominent and sustainable performance, compared to a conventional double pipe heat exchanger (DPHE), with an enhancement in heat transfer rate up to 32% and performance factor (PF) higher than one. Another appealing merit for the C-DPHE is that it is quite effective and functional at low Reynolds and high Prandtl numbers, respectively, since no high-operating pumping power is required. Further, the optimal operating conditions can be established utilizing the comprehensive information provided in this work.

Geothermal Power Cycle Analysis for Commercial Applicability Using Sequestered Supercritical CO2 as a Heat Transfer or Working Fluid

2011 ◽  
Author(s):  
Brian Janke ◽  
Thomas Kuehn
Keyword(s):  
Heat Transfer ◽  
Binary System ◽  
Power Plants ◽  
Power Production ◽  
Operating Conditions ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Direct System ◽  
Geothermal Power ◽  
The Impact

Thermodynamic analysis has been conducted for geothermal power cycles using a portion of deep ground sequestered CO2 as the working fluid. This allows energy production from much shallower depths and in geologic areas with much lower temperature gradients than those of current geothermal systems. Two different system designs were analyzed for power production with varying reservoir parameters, including reservoir depth, temperature, and CO2 mass flow rate. The first design is a direct single-loop system with the CO2 run directly through the turbine. This system was found to provide higher system efficiency and power production, however design complications such as the need for high pressure turbines, two-phase flow through the turbine and the potential for water-CO2 brine mixtures, could require the use of numerous custom components, driving up the cost. The second design is a binary system using CO2 as the heat transfer fluid to supply thermal energy to an Organic Rankine Cycle (ORC). While this system was found to have slightly less power production and efficiency than the direct system, it significantly reduces the impact of design complications associated with the direct system. This in turn reduces the necessity for certain custom components, thereby reducing system cost. While performance of these two systems is largely dependent on location and operating conditions, the binary system is likely applicable to a larger number of sites and will be more cost effective when used in combination with current off-the-shelf ORC power plants.

Conjugate heat transfer simulation of turbine blade high efficiency cooling method with mist injection

2014 ◽  
Vol 228 (15) ◽  
pp. 2738-2749 ◽  
Author(s):  
Yuting Jiang ◽  
Qun Zheng ◽  
Guoqiang Yue ◽  
Ping Dong ◽  
Jie Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Conjugate Heat Transfer ◽  
High Efficiency ◽  
Turbulence Models ◽  
Operating Conditions ◽  
Cooling Performance ◽  
Convective Cooling ◽  
Mist Cooling ◽  
The Impact

The idea of utilizing a finely dispersed water-in-air mixture has been proven to be a feasible technique to produce very high cooling rates. The accuracy of numerical simulation program for conjugate heat transfer methodology is verified with the Mark II transonic high pressure turbine stator which is cooled by internal convection through radial round pipes, and different turbulence models and transition models are employed to analyze the influence on results. On the basis of it, the mist cooling is simulated under typical gas turbine operating conditions for internal convective cooling to discuss the improvement of cooling performance. Though the results indicate that mist cooling can decrease the temperature of boundary layer without impact on the temperature of the mainstream and the thickness of boundary layer, the cooling capacity is limited by inadequate evaporation of mist. Considering the distribution of thermal stress and mist evaporation, a compound cooling blade of film cooling with trailing edge ejection is acquired which is modified from the blade of Mark II internal convective cooling; the effects of various parameters including mist concentration and mist diameter on the improvement of cooling performance are investigated, meanwhile the impact of curvature on cooling efficiency and mist trajectory is analyzed finally.

Spatial and Temporal Wall Temperature Fluctuations in Two-Phase Flow in Microgap Coolers

2010 ◽  
Author(s):  
Jessica Sheehan ◽  
Avram Bar-Cohen
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Volumetric Cooling ◽  
Very High

Heat transfer to an evaporating refrigerant and/or dielectric liquid in a microgap channel can provide very high heat transfer coefficients and volumetric cooling rates. Recent studies at Maryland have established the dominance of the annular flow regime in such microgap channels and related the observed high-quality peak of an M-shaped heat transfer coefficient curve to the onset of local dryout. The present study utilizes infrared thermography to locate such nascent dryout regions and operating conditions. Data obtained with a 210 micron microgap channel, operated with a mass flux of 195.2 kg/m2-s and heat fluxes of 10.3 to 26 W/cm2 are presented and discussed.

Visualization of the Heat Transfer Enhancement During Condensation in a Microfin Tube

2006 ◽  
Author(s):  
Alberto Cavallini ◽  
Davide Del Col ◽  
Luca Doretti ◽  
Simone Mancin ◽  
Luisa Rossetto ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Saturation Temperature ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Vapor Quality ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Plain Tube ◽  
The Heat Transfer Coefficient

Microfins tubes are largely used in refrigeration industry for in-tube refrigerant condensation, because of the heat transfer enhancement when compared to equivalent smooth tubes under the same operating conditions. But not much evidence about the effect of microfins on the condensation flow patterns is available in the open literature. There is agreement in the open literature that the mechanisms of heat transfer are intimately linked with the prevailing two-phase flow regime. The present authors have recently measured the heat transfer coefficient during condensation of R410A in a microfin tube. The heat transfer enhancement in this tube can be experimentally evaluated by comparing those coefficients to the ones measured by Cavallini et al. (2001) in a plain tube, at the same operating conditions. The same operative conditions (saturation temperature, vapor quality and mass flux), occurring during the heat transfer measurements, were reproduced in a different section for visualization of flow patterns during condensation of R410A. The flow visualization has been carried out both in the plain tube and in the microfin tube. The objective of the present paper is to present the heat transfer enhancement during condensation of R410A and to show the flow visualized at the same operating condition for both the smooth and the microfin tube, aiming to link the heat transfer enhancement to the flow pattern variation.

3D IC With Embedded Microfluidic Cooling: Technology, Thermal Performance, and Electrical Implications

2015 ◽  
Author(s):  
Xuchen Zhang ◽  
Xuefei Han ◽  
Thomas E. Sarvey ◽  
Craig E. Green ◽  
Peter A. Kottke ◽  
...  
Keyword(s):  
Heat Sink ◽  
Single Phase ◽  
Electrical Performance ◽  
Thermal Testing ◽  
Two Phase ◽  
Cooling Technology ◽  
Silicon Vias ◽  
The Impact ◽  
Measured Pressure ◽  
The Heat Transfer Coefficient

In this paper, a novel thermal testbed with an embedded micropin-fin heat sink is designed and fabricated. The micropin-fin array has a nominal height of 200 μm and a diameter of 90 μm. Single phase and two phase thermal testing of the micropin-fin array heat sink are performed using deionized (D.I.) water as the coolant below atmospheric pressure. The measured pressure drop is as high as 100 kPa with a mass flux of 1637 kg/m2s at a heat flux of 400 W/cm2 in a two-phase regime. The heat transfer coefficient and the vapor quality are calculated and reported. The impact of microfluidic cooling on the electrical performance of the 3D interconnects is also analyzed. The high aspect ratio through silicon vias (TSVs) used in the electrical analysis have a nominal diameter of 10 μm.

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