Coanda Principles for Giant Efficiency Enhancements in Cooling Computers
- Samir Anz, Professor of Chemistry, California State Polytechnic University Pomona
- Phyllis Nelson, Professor of Electrical Engineering, California State Polytechnic University Pomona
In September of 2001, Google Inc. finally admitted to its large carbon footprint (1) associated with its data centers. Cooling needs for these centers is a major consumer of energy and a major source of noise pollution.
We describe the use of Coanda Principles to provide giant enhancements to the cooling of computer clusters. Central Processing Units (CPU) perform faster at colder temperatures. With the processing power of computers increasing because of our ability to shrink transistor, it has become a challenge to adequately cool these CPUs. Moreover, variations in temperature decrease the reliability of the CPUs and associated circuit boards.
Our hypothesis is that Coanda airflow will more efficiently cool a CPU than airflow from conventional fans. We tested this hypothesis by building two identical fan housings, however inside one of the housings we placed a Coanda element that converted air from a conventional fan into vectorial flow. The air output from each housing was used to cool a light bulb, which simulates a 65 watt CPU.
The temperature profiles of the light bulbs were used to determine the cooling efficiency. Various experiments involving delaying the start of the lamp and/or the fan were carried out in efforts to simulate real CPU usage. We determined that the heating rate of the light bulb cooled using Coanda's principles was half the rate of the light bulb cooled with conventional fan. The maximum temperature also attained by fan with Coanda effect was 25% lower than one with non-Coanda fan. In addition we observed cool down rates four times faster with Coanda-enabled fan. We can increase the efficiency of existing clusters with these principles that require only small structural modifications to existing hadware.
(1) http://www.google.com/green/the-big-picture.html and http://www.guardian.co.uk/environment/2011/sep/08/google-carbon-footprint