Hot Spot Cooling and Harvesting CPU Waste Heat Using Thermoelectric Modules

Author(s):  
Soochan Lee ◽  
Patrick E. Phelan ◽  
Carole-Jean Wu

The increasing integration of high performance processors and dense circuits in current computing devices has produced high heat flux in localized areas (hot spots) that limits their performance and reliability. To control the hot spots on a CPU, many researchers have focused on active cooling methods such as thermoelectric coolers (TECs) to avoid thermal emergencies. This paper presents the optimized thermoelectric modules on top of the CPU combined with a conventional air-cooling device to reduce the hot spot temperature and at the same time harvest waste heat energy generated by the CPU. To control the temperature of the hot spots, we attach small-sized TECs to the CPU and use thermoelectric generators (TEGs) placed on the rest of the CPU to convert waste heat energy into electricity. This study investigates design alternatives with an analytical model considering the non-uniform temperature distribution based on two-node thermal networks. The results indicate that we are able to attain more energy from the TEGs than energy consumption for running the TECs. In other words, we can allow the harvested heat energy to be reused to power other components and reduce hot spots simultaneously. Overall, the idea of simultaneous hot spot cooling and waste heat harvesting using thermoelectric modules on a CPU is a promising method to control the problem of heat generation and to reduce energy consumption in a computing device.

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Soochan Lee ◽  
Patrick E. Phelan ◽  
Carole-Jean Wu

The increasing integration of high performance processors and dense circuits in current computing devices has produced high heat flux in localized areas (hot spots), which limits their performance and reliability. To control the hot spots on a central processing unit (CPU), many researchers have focused on active cooling methods such as thermoelectric coolers (TECs) to avoid thermal emergencies. This paper presents optimized thermoelectric modules on top of the CPU combined with a conventional air-cooling device to reduce the core temperature and at the same time harvest waste heat energy generated by the CPU. To control the temperature of the cores, we attach small-sized TECs to the CPU and use thermoelectric generators (TEGs) placed on the rest of the CPU to convert waste heat energy into electricity. This study investigates design alternatives with an analytical model considering the nonuniform temperature distribution based on two-node thermal networks. The results indicate that we are able to attain more energy from the TEGs than energy consumption for running the TECs. In other words, we can allow the harvested heat energy to be reused to power other components and reduce cores temperature simultaneously. Overall, the idea of simultaneous core cooling and waste heat harvesting using thermoelectric modules on a CPU is a promising method to control the problem of heat generation and to reduce energy consumption in a computing device.


2013 ◽  
Vol 455 ◽  
pp. 466-469
Author(s):  
Yun Chuan Wu ◽  
Shang Long Xu ◽  
Chao Wang

With the increase of performance demands, the nonuniformity of on-chip power dissipation becomes greater, causing localized high heat flux hot spots that can degrade the processor performance and reliability. In this paper, a three-dimensional model of the copper microchannel heat sink, with hot spot heating and background heating on the back, was developed and used for numerical simulation to predict the hot spot cooling performance. The hot spot is cooled by localized cross channels. The pressure drop, thermal resistance and effects of hot spot heat flux and fluid flow velocity on the cooling of on-chip hot spots, are investigated in detail.


Author(s):  
Sebastian Knirsch ◽  
Dietmar Mandt ◽  
Uwe Mauch ◽  
Konrad Bamberger ◽  
Thomas Carolus

An important subsystem in most surface transport vehicles is the forced-air cooling module. Under specific operational conditions of the vehicle the cooling system is the major noise source and the component with the largest consumption of energy. A comprehensive time domain simulation model was developed for simulation of the cooling module in a Diesel locomotive under realistic operational conditions. It includes the components that produce waste heat such as the engine, the turbo transmission, the brake, etc. and the cooling module with its fans. Given the operation of the locomotive e.g. in terms of speed vs. time along a track and its load, data from experimental full scale tests agree well with predictions from the time domain model. The onset of cooling fan operation is predicted well, with it their instantaneous energy consumption and sound radiation. Three optimized cooling unit assemblies for the new locomotive Voith Gravita 15L had been developed and pre-assessed utilizing the model and eventually tested in the locomotive under realistic operational conditions. A new thermodynamically advanced cooling unit with aerodynamically and acoustically optimized fans was found superior by approx. 2 dB (A) less sound power radiation and some 30% less energy consumption as compared to the benchmark. It is anticipated that those advantages are even more distinct as the ambient temperature decreases. The work is part of the European FP7 transport research project ECOQUEST.


2009 ◽  
Vol 30 (9) ◽  
pp. 736-743 ◽  
Author(s):  
Peng Wang ◽  
Bao Yang ◽  
Avram Bar-Cohen

Author(s):  
Chien Ouyang ◽  
Kenny Gross ◽  
Ali Heydari

The paper describes a novel approach for achieving enhanced energy efficiency for computer servers. The paper teaches a novel solid-state technique and apparatus for recycling waste heat from chip packages and turning that wasted energy into hot-spot cooling for other IC packages in the same server. This approach brings the combined advantages of enhanced energy efficiency while smoothing out the spatial and temporal thermal gradients, thereby yielding better long term reliability for multiple-chip enterprise servers.


Author(s):  
Fernando Gielow ◽  
Michele Nogueira ◽  
Aldri Santos

The use of Wireless Sensor Networks (WSNs) has increased over the past years, supporting applications such as environmental monitoring, security systems, and multimedia streaming. These networks are characterized by a many-to-one traffic pattern. Hence, sensor nodes near to the sink have higher energy consumption, being prone to earlier deaths and failures. Those areas overloaded with high traffic rates are called Hot Spots, and their emergence creates and expands energy holes that compromise network lifetime and data delivery rates, and may result in disconnected areas. This chapter provides an overview of techniques to mitigate Hot Spot impacts, such as the uneven distribution of sensors, routes that balance energy consumption, sink mobility, and the use of unequal clustering. Further, it depicts the approach for achieving mitigation of sink centered Hot Spots. Finally, this chapter presents conclusions and future research perspectives.


Author(s):  
Matthew Redmond ◽  
Kavin Manickaraj ◽  
Owen Sullivan ◽  
Satish Kumar

Three dimensional (3D) technologies with stacked chips have the potential to provide new chip architecture, improved device density, performance, efficiency, and bandwidth. Their increased power density also can become a daunting challenge for heat removal. Furthermore, power density can be highly non-uniform leading to time and space varying hotspots which can severely affect performance and reliability of the integrated circuits. Thus, it is important to mitigate thermal gradients on chip while considering the associated cooling costs. One method of thermal management currently under investigation is the use of superlattice thermoelectric coolers (TECs) which can be employed for on demand and localized cooling. In this paper, a detailed 3D thermal model of a stacked electronic package with two dies and four ultrathin integrated TECs is studied in order to investigate the efficacy of TECs in hot spot cooling for a 3D technology. We observe up to 14.6 °C of cooling at a hot spot inside the package by TECs. A strong vertical coupling has been observed between the TECs located in top and bottom dies. Bottom TECs can detrimentally heat the top hotspots in both steady state and transient operation. TECs need to be carefully placed inside the package to avoid such undesired heating. Thermal contact resistances between dies, inside the TEC module, and between the TEC and heat spreader are shown to have a crucial effect on TEC performance inside the package. We observed that square root current pulse can provide very efficient short-duration transient cooling at hotspots.


2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Owen Sullivan ◽  
Man Prakash Gupta ◽  
Saibal Mukhopadhyay ◽  
Satish Kumar

Site-specific on-demand cooling of hot spots in microprocessors can reduce peak temperature and achieve a more uniform thermal profile on chip, thereby improve chip performance and increase the processor’s life time. An array of thermoelectric coolers (TECs) integrated inside an electronic package has the potential to provide such efficient cooling of hot spots on chip. This paper analyzes the potential of using multiple TECs for hot spot cooling to obtain favorable thermal profile on chip in an energy efficient way. Our computational analysis of an electronic package with multiple TECs shows a strong conductive coupling among active TECs during steady-state operation. Transient operation of TECs is capable of driving cold-side temperatures below steady-state values. Our analysis on TEC arrays using current pulses shows that the effect of TEC coupling on transient cooling is weak. Various pulse profiles have been studied to illustrate the effect of shape of current pulse on the operation of TECs considering crucial parameters such as total energy consumed in TECs peak temperature on the chip, temperature overshoot at the hot spot and settling time during pulsed cooling of hot spots. The square root pulse profile is found to be the most effective with maximum cooling and at half the energy expenditure in comparison to a constant current pulse. We analyze the operation of multiple TECs for cooling spatiotemporally varying hot spots. The analysis shows that the transient cooling using high amplitude current pulses is beneficial for short term infrequent hot spots, but high amplitude current pulse cannot be used for very frequent or long lasting hot spots.


Author(s):  
Phil Paik ◽  
Vamsee K. Pamula ◽  
Krishnendu Chakrabarty

Thermal management is becoming an increasingly important issue in integrated circuit (IC) design. The ability to cool ICs is quickly reaching a limit with today’s package-level solutions. While a number of novel cooling methods have been introduced, many of which are microfluidic approaches, these methods are unable to adaptively address the uneven thermal profiles and hot-spots generated in high performance ICs. In this paper, we present a droplet-based digital microfluidic cooling system for ICs that can adaptively cool hot-spots through real-time reprogrammable flow. This paper characterizes the effectiveness of microliter-sized droplets for cooling by determining the heat transfer coefficient of a droplet shuttling back and forth in an open system over a hot-spot at various speeds. Cooling is found to be significantly enhanced at higher flow rates of droplets. In order to further enhance cooling, the effect of varying droplet aspect ratio (width/height) in a confined system was also studied.


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