The relationship among CPU utilization, temperature, and thermal power for waste heat utilization

Anna M. Haywood, Jon Sherbeck, Patrick Phelan, Georgios Varsamopoulos, Sandeep Gupta

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


This work addresses significant datacenter issues of growth in numbers of computer servers and subsequent electricity expenditure by proposing, analyzing and testing a unique idea of recycling the highest quality waste heat generated by datacenter servers. The aim was to provide a renewable and sustainable energy source for use in cooling the datacenter. The work incorporates novel approaches in waste heat usage, graphing CPU temperature, power and utilization simultaneously, and a mineral oil experimental design and implementation. The work presented investigates and illustrates the quantity and quality of heat that can be captured from a variably tasked liquid-cooled microprocessor on a datacenter server blade. It undertakes a radical approach using mineral oil. The trials examine the feasibility of using the thermal energy from a CPU to drive a cooling process. Results indicate that 123 servers encapsulated in mineral oil can power a 10-ton chiller with a design point of 50.2 kWth. Compared with water-cooling experiments, the mineral oil experiment mitigated the temperature drop between the heat source and discharge line by up to 81%. In addition, due to this reduction in temperature drop, the heat quality in the oil discharge line was up to 12.3 °C higher on average than for water-cooled experiments. Furthermore, mineral oil cooling holds the potential to eliminate the 50% cooling expenditure which initially motivated this project.

Original languageEnglish (US)
Pages (from-to)297-303
Number of pages7
JournalEnergy Conversion and Management
StatePublished - May 1 2015


  • Absorption chiller
  • CPU heat, power and temperature simultaneously
  • Data center waste heat
  • Heat-extraction
  • Liquid cooling
  • Waste heat reuse

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology


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