Minimizing the Effects of On-Chip Hotspots Using Multi-Objective Optimization of Flow Distribution in Water-Cooled Parallel Microchannel Heatsinks

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Yaser Hadad ◽  
Vahideh Radmard ◽  
Srikanth Rangarajan ◽  
Mahdi Farahikia ◽  
Gamal Refai-Ahmed ◽  
...  
Keyword(s):  
Flow Distribution ◽  
System Level ◽  
Temperature Uniformity ◽  
Liquid Cooling ◽  
Two Phase ◽  
Chip Area ◽  
Chip Temperature ◽  
Cooling Design ◽  
On Chip ◽  
Novel Concept

Abstract The industry shift to multicore microprocessor architecture will likely cause higher temperature nonuniformity on chip surfaces, exacerbating the problem of chip reliability and lifespan. While advanced cooling technologies like two phase embedded cooling exist, the technological risks of such solutions make conventional cooling technologies more desirable. One such solution is remote cooling with heatsinks with sequential conduction resistance from chip to module. The objective of this work is to numerically demonstrate a novel concept to remotely cool chips with hotspots and maximize chip temperature uniformity using an optimized flow distribution under constrained geometric parameters for the heatsink. The optimally distributed flow conditions presented here are intended to maximize the heat transfer from a nonuniform chip power map by actively directing flow to a hotspot region. The hotspot-targeted parallel microchannel liquid cooling design is evaluated against a baseline uniform flow conventional liquid cooling design for the industry pressure drop limit of approximately 20 kPa. For an average steady-state heat flux of 145 W/cm2 on core areas (hotspots) and 18 W/cm2 on the remaining chip area (background), the chip temperature uniformity is improved by 10%. Moreover, the heatsink design has improved chip temperature uniformity without a need for any additional system level complexity, which also reduces reliability risks.

Dynamic Modeling of a Two-Phase On-Chip Cooling System Applied on Parallel High Performance Microprocessors

2013 ◽  
Author(s):  
Nicolas Lamaison ◽  
Jackson B. Marcinichen ◽  
John R. Thome
Keyword(s):  
Heat Flux ◽  
Heat Load ◽  
Cooling System ◽  
Saturation Temperature ◽  
Vapor Quality ◽  
Two Phase ◽  
Chip Temperature ◽  
High Heat Transfer ◽  
On Chip ◽  
Liquid Pump

Transient modeling and control of two-phase on-chip microevaporator cold plates of a liquid pump cooling cycle is studied. The purpose is to cool down multiple micro-processors in parallel and their auxiliary electronics (memories, DC/DC converters, etc.) in series. The cooling system is composed of multiple on-chip microevaporators in parallel, a condenser, a liquid accumulator, a liquid pump and all piping joining these components. In order to achieve high heat transfer and chip temperature uniformity, two-phase flow of HFC134a is considered for the coolant. The dynamics of the system are relevant aspects to be studied since the heat dissipated by the microprocessors is changing continuously. Thus, a new simulation code has been developed here to emulate the operation during transients. Such transient simulations allow us to verify whether critical heat flux (CHF) conditions are reached during heat load disturbances and to track the available heat at the condenser for energy recovery purposes. Presently, a case study with four microprocessors cooled in parallel flow is simulated considering different levels of uniform heat flux (36, 30, 25 and 10 Wcm−2), which showed the robustness of the predictive-corrective solver used. For a desired exit mixing vapor quality of 30%, at an inlet pressure and subcooling of respectively 16 bar (saturation temperature of 57.9 °C) and 2 K, the resulting distribution of the mass flow rates in the microevaporators were 3.6, 4.0, 4.5 and 7.4 kg/h (largest flow rate for lowest heat load) and the total pressure drop over the entire section was 0.6 kPa. The CHF and maximum chip temperature remained below of the critical limits. Preliminary comparisons with experimental tests showed errors in the predictions of mean chip temperature and mixing vapor quality to be within ±10%.

Experimental Research on Phase-Change Cooling for High-Power Chip

2014 ◽  
Vol 628 ◽  
pp. 306-310
Author(s):  
Long Sheng Wu ◽  
Xu Zhang ◽  
Cheng Jian Wang ◽  
Zhen Long Wang
Keyword(s):  
Heat Flux ◽  
Phase Change ◽  
Single Phase ◽  
Experimental System ◽  
Temperature Uniformity ◽  
Pumping Power ◽  
Liquid Cooling ◽  
Chip Temperature ◽  
Phase Liquid ◽  
Cooling Technology

Phase change cooling technology is based on the boiling of refrigerating medium to absorb the heat generated by the electronic chip. It provides higher heat flux dissipation, reduces the refrigerating medium flux and consumes a lower pumping power, compared with single-phase liquid cooling. It also has good temperature uniformity and higher working temperature, which is ideal for energy reuse. Experimental system was designed for phase change cooling of R123 to analyze the basic conditions required for boiling vaporization. The chip temperature was 70 °C or less when the heat flux was 100 W·cm-2, with the 0.6 mm rectangular micro-channel evaporator. Experiments were conducted to analyze the effects of heat flux, channel dimension, throttling action on the heat transfer effect.

Two-Phase Mini-Thermosyphon for Cooling of Datacenters: Experiments, Modeling and Simulations

2017 ◽  
Author(s):  
Chin L. Ong ◽  
Raffaele L. Amalfi ◽  
Jackson B. Marcinichen ◽  
Nicolas Lamaison ◽  
John R. Thome
Keyword(s):  
Acoustic Noise ◽  
Heat Removal ◽  
Flow Distribution ◽  
Heat Fluxes ◽  
Air Cooling ◽  
Two Phase ◽  
Simulation Code ◽  
Experimental Database ◽  
Error Band ◽  
Chip Temperature

Nowadays, datacenters heat density dissipation follows an exponential increasing trend that is reaching the heat removal limits of the traditional air-cooling technology. Two-phase cooling implemented within a gravity-driven system represents a scalable and viable long-term solution for datacenter cooling in order to increase the heat density dissipation with larger energy efficiency and lower acoustic noise. The present article builds upon the 4-part set of papers presented at ITHERM 2016 for a 15-cm height thermosyphon to cool a contemporary datacenter cabinet, providing new test data over a wider range of heat fluxes and new validations of the thermal-hydrodynamics of our thermosyphon simulation code. The thermosyphon consists of a microchannel evaporator connected via a riser and a downcomer to a liquid-cooled condenser for the cooling of a pseudo-chip to emulate an actual server. Test results demonstrated good thermal performance coupled with uniform flow distribution for the new larger range of operating test conditions. At the maximum imposed heat load of 158 W (corresponding to a heat flux of 70 W cm−2) with a water inlet coolant at 20 °C, water mass flow rate of 12 kg h−1 and thermosyphon filling ratio of 78%, the pseudo mean chip temperature was found to be 58 °C and is well below the normal thermal limits in datacenter cooling. Finally, the in-house LTCM’s thermosyphon simulation code was validated against an expanded experimental database of about 262 data points, demonstrating very good agreement; in fact, the pseudo mean chip temperature was predicted with an error band of about 1 K.

scholarly journals Two-Phase Turbulence Statistics from High Fidelity Dispersed Droplet Flow Simulations in a Pressurized Water Reactor (PWR) Sub-Channel with Mixing Vanes

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 72
Author(s):  
Nadish Saini ◽  
Igor A. Bolotnov
Keyword(s):  
Continuous Phase ◽  
System Level ◽  
Data Repository ◽  
High Fidelity ◽  
Turbulence Statistics ◽  
Two Phase ◽  
Pressurized Water ◽  
Droplet Dynamics ◽  
High Resolution Data ◽  
Spacer Grids

In the dispersed flow film boiling regime (DFFB), which exists under post-LOCA (loss-of-coolant accident) conditions in pressurized water reactors (PWRs), there is a complex interplay between droplet dynamics and turbulence in the surrounding steam. Experiments have accredited particular significance to droplet collision with the spacer-grids and mixing vane structures and their consequent positive feedback to the heat transfer recorded in the immediate downstream vicinity. Enabled by high-performance computing (HPC) systems and a massively parallel finite element-based flow solver—PHASTA (Parallel Hierarchic Adaptive Stabilized Transient Analysis)—this work presents high fidelity interface capturing, two-phase, adiabatic simulations in a PWR sub-channel with spacer grids and mixing vanes. Selected flow conditions for the simulations are informed by the experimental data found in the literature, including the steam Reynolds number and collision Weber number (Wec={40,80}), and are characteristic of the DFFB regime. Data were collected from the simulations at an unprecedented resolution, which provides detailed insights into the continuous phase turbulence statistics, highlighting the effects of the presence of droplets and the comparative effect of different Weber numbers on turbulence in the surrounding steam. Further, axial evolution of droplet dynamics was analyzed through cross-sectionally averaged quantities, including droplet volume, surface area and Sauter mean diameter (SMD). The downstream SMD values agree well with the existing empirical correlations for the selected range of Wec. The high-resolution data repository from the simulations herein is expected to be of significance to guide model development for system-level thermal hydraulic codes.

scholarly journals Design of a Real-Time Breakdown Voltage and On-Chip Temperature Monitoring System for Single Photon Avalanche Diodes

Electronics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 25
Author(s):  
Shijie Deng ◽  
Alan P. Morrison ◽  
Yong Guo ◽  
Chuanxin Teng ◽  
Ming Chen ◽  
...  
Keyword(s):  
Real Time ◽  
Breakdown Voltage ◽  
Count Rate ◽  
Single Photon ◽  
Photon Counting ◽  
Temperature Monitoring ◽  
Dark Count ◽  
Chip Temperature ◽  
Avalanche Diodes ◽  
On Chip

The design and implementation of a real-time breakdown voltage and on-chip temperature monitoring system for single photon avalanche diodes (SPADs) is described in this work. In the system, an on-chip shaded (active area of the detector covered by a metal layer) SPAD is used to provide a dark count rate for the breakdown voltage and temperature calculation. A bias circuit was designed to provide a bias voltage scanning for the shaded SPAD. A microcontroller records the pulses from the anode of the shaded SPAD and calculates its real-time dark count rate. An algorithm was developed for the microcontroller to calculate the SPAD’s breakdown voltage and the on-chip temperature in real time. Experimental results show that the system is capable of measuring the SPAD’s breakdown voltage with a mismatch of less than 1.2%. Results also show that the system can provide real-time on-chip temperature monitoring for the range of −10 to 50 °C with errors of less than 1.7 °C. The system proposed can be used for the real-time SPAD’s breakdown voltage and temperature estimation for dual-SPADs or SPAD arrays chip where identical detectors are fabricated on the same chip and one or more dummy SPADs are shaded. With the breakdown voltage and the on-chip temperature monitoring, intelligent control logic can be developed to optimize the performance of the SPAD-based photon counting system by adjusting the parameters such as excess bias voltage and dead-time. This is particularly useful for SPAD photon counting systems used in complex working environments such as the applications in 3D LIDAR imaging for geodesy, geology, geomorphology, forestry, atmospheric physics and autonomous vehicles.

scholarly journals Variational formulation of stationary two-phase flow distribution

2021 ◽  
pp. 101082
Author(s):  
Niccolo Giannetti ◽  
Mark A.B. Redo ◽  
Kiyoshi Saito ◽  
Hiroaki Yoshimura
Keyword(s):  
Variational Formulation ◽  
Two Phase Flow ◽  
Flow Distribution ◽  
Phase Flow ◽  
Two Phase

scholarly journals Thermal Analysis of Cold Plate with Different Configurations for Thermal Management of a Lithium-Ion Battery

Batteries ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 17
Author(s):  
Seyed Saeed Madani ◽  
Erik Schaltz ◽  
Søren Knudsen Kær
Keyword(s):  
Thermal Analysis ◽  
Temperature Distribution ◽  
Lithium Ion Battery ◽  
Thermal Management ◽  
Electric Vehicles ◽  
Heat Dissipation ◽  
Lithium Ion ◽  
Cold Plate ◽  
Liquid Cooling ◽  
Cooling Design

Thermal analysis and thermal management of lithium-ion batteries for utilization in electric vehicles is vital. In order to investigate the thermal behavior of a lithium-ion battery, a liquid cooling design is demonstrated in this research. The influence of cooling direction and conduit distribution on the thermal performance of the lithium-ion battery is analyzed. The outcomes exhibit that the appropriate flow rate for heat dissipation is dependent on different configurations for cold plate. The acceptable heat dissipation condition could be acquired by adding more cooling conduits. Moreover, it was distinguished that satisfactory cooling direction could efficiently enhance the homogeneity of temperature distribution of the lithium-ion battery.

Sign in / Sign up

Export Citation Format

Share Document