The depletion of the world's limited reservoirs of fossil fuels, the worldwide impact of global warming and the high cost of energy are among the primary issues driving a renewed interest in the capture and reuse of waste energy. A major source of waste energy is being created by data centers through the increasing demand for cloud based connectivity and performance. In fact, recent figures show that data centers are responsible for more than 2% of the US total electricity usage. Almost half of this power is used for cooling the electronics, creating a significant stream of waste heat. The difficulty associated with recovering and reusing this stream of waste heat is that the heat is of low quality. In this paper, the most promising methods and technologies for recovering data center low-grade waste heat in an effective and economically reasonable way are identified and discussed. A number of currently available and developmental low-grade waste heat recovery techniques including district/plant/water heating, absorption cooling, direct power generation (piezoelectric and thermoelectric), indirect power generation (steam and organic Rankine cycle), biomass co-location, and desalination/clean water are reviewed along with their operational requirements in order to assess the suitability and effectiveness of each technology for data center applications. Based on a comparison between data centers' operational thermodynamic conditions and the operational requirements of the discussed waste heat recovery techniques, absorption cooling and organic Rankine cycle are found to be among the most promising technologies for data center waste heat reuse.

A review of data center cooling technology, operating conditions and the corresponding low-grade waste heat recovery opportunities

Review of pool boiling enhancement by surface modification

Review of computational studies on boiling and condensation

Universal approach to predicting saturated flow boiling heat transfer in mini/micro-channels - Part II. Two-phase heat transfer coefficient

A Review on efficient thermal management of air- and liquid-cooled data centers: From chip to the cooling system

https://engineering.purdue.edu/BTPFL/BTPFL%20Publications/113.pdf

Experimental and numerical investigation of single-phase heat transfer using a hybrid jet-impingement/micro-channel cooling scheme

Single-phase hybrid micro-channel/micro-jet impingement cooling

Single-phase and two-phase heat transfer characteristics of low temperature hybrid micro-channel/micro-jet impingement cooling module

This study examines the cooling performance of two hybrid cooling schemes that capitalize on the merits of both microchannel flow and jet impingement to achieve the high cooling fluxes and uniform temperatures demanded by advanced defense electronics. The jets supply HFE 7100 liquid coolant gradually into each microchannel. The cooling performances of two different jet configurations, a series of circular jets and a single slot jet, are examined both numerically and experimentally. The single-phase performances of both configurations are accurately predicted using 3D numerical simulation. Numerical results point to complex interactions between the jets and the microchannel flow, and superior cooling performance is achieved by optimal selection of microchannel height. The two-phase cooling performance of the circular-jet configuration is found superior to that of the slot jet, especially in terms of high-flux heat dissipation. Unprecedented cooling fluxes, as high as 1127 W/cm 2 , are achieved with the circular jets without incurring CHF.

Myung Ki Sung

Papers

Experimental and numerical investigation of single-phase heat transfer using a hybrid jet-impingement/micro-channel cooling scheme

Single-phase hybrid micro-channel/micro-jet impingement cooling

Single-phase and two-phase heat transfer characteristics of low temperature hybrid micro-channel/micro-jet impingement cooling module

Single-Phase and Two-Phase Hybrid Cooling Schemes for High-Heat-Flux Thermal Management of Defense Electronics

Single-phase and two-phase cooling using hybrid micro-channel/slot-jet module