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Hybrid Dual-Loop Liquid-Air Cooling System With Thermoelectrically Coupled Cold Plates

IP.com Disclosure Number: IPCOM000015399D
Original Publication Date: 2002-May-21
Included in the Prior Art Database: 2003-Jun-20
Document File: 5 page(s) / 113K

Publishing Venue

IBM

Abstract

As CMOS circuit and process technology approaches its scaling limits, it will become necessary to consider other technology approaches and opportunities to achieve further performance gains. One approach which is receiving increased attention is the operation of CMOS at lower temperatures. The circuit performance improvements which may be attained vary from about 1.1x at a cooling condition of 25 C, to 1.8x at a cooling condition of -200 C. To obtain cooling conditions down to about 50 C or so, conventional vapor-compression refrigeration techniques may be used. However, conventional vapor-compression refrigeration systems may have difficulty in handling variations in heat load, and may not be as responsive as desired under transient operating conditions. The invention disclosed here utilizes dual liquid loops with thermoelectrically coupled cold plates to provide water below ambient air temperatures to cool multiple electronic modules. The total heat load from the electronic modules and thermoelectric cooling modules is then rejected to ambient air through a compact liquid-to-air heat exchanger.

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  Hybrid Dual-Loop Liquid-Air Cooling System With Thermoelectrically Coupled Cold Plates

   As CMOS circuit and process technology approaches its scaling limits, it will become necessary to consider other technology approaches and opportunities to achieve further performance gains. One approach which is receiving increased attention is the operation of CMOS at lower temperatures. The circuit performance improvements which may be attained vary from about 1.1x at a cooling condition of 25 C, to 1.8x at a cooling condition of -200 C. To obtain cooling conditions down to about - 50 C or so, conventional vapor-compression refrigeration techniques may be used. However, conventional vapor-compression refrigeration systems may have difficulty in handling variations in heat load, and may not be as responsive as desired under transient operating conditions. The invention disclosed here utilizes dual liquid loops with thermoelectrically coupled cold plates to provide water below ambient air temperatures to cool multiple electronic modules. The total heat load from the electronic modules and thermoelectric cooling modules is then rejected to ambient air through a compact liquid-to-air heat exchanger.

Before describing the invention in greater detail, alternative approaches utilizing thermoelectric modules to augment cooling of electronic modules will be briefly described to place in proper perspective the advantages of the invention disclosed herein. Figure 1 illustrates the use of direct air cooling with thermoelectric augmentation. To achieve reduced operating temperatures the cold-side of the thermoelectric modules are placed in contact with the cooling surface of an electronic module. An air-cooled heat sink which must be large enough to handle power dissipation of both the electronic module and the thermoelectric cooling modules is placed in contact with the hot-side of the thermoelectric modules. In general individual thermoelectric modules exhibit relatively low heat 2flux capability in the order of a few watts/cm at any useful temperature difference from hot to cold side. Considering the confined space typically available around an electronic module the cooling augmentation provided by the thermoelectric modules will be limited. This limitation will be further exacerbated by the limited space available for the air-cooled heat sink. It may be appreciated that in the case of multiple modules packaged closely together the effectiveness of thermoelectric augmentation will be even further reduced.

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Electronic Module

Air-Cooled Heat Sink

Thermoelectric Cooling Module(s)

Air Moving Device

Board

Figure 1. Direct air cooling with thermoelectric augmentation.

The limitations imposed by an air-cooled heat sink attached to the thermoelectric module(s) may be somewhat reduced by using liquid-cooled cold plates as shown in figure 2. Again in this case the cold-side of the thermoelectric cooling module(s) is placed in contact with the heat r...