Ultrasonic Humidification in the Data Center Part II

In Part I of the Ultrasonic Humidification in the Data Center article, we examined Ultrasonic Humidification principles and learned why it is more efficient that traditional humidification methods. In Part II, we will examine detailed Ultrasonic Humidification design information as well as cost savings.

Little data is available to fully evaluate the use of Ultrasonic Humidification in data center design. We do know that several large data centers have begun implementing ultrasonic humidification as part of their cooling and environmental conditioning methods. It is known that companies such as Google, HP, Amazon and Bank of America each have multiple sites with Ultrasonic Humidification.

The main issue in developing statistics on the use of Ultrasonic Humidification is that there are relatively few industrial grade Ultrasonic Humidification manufacturers. As mentioned in Part I, Humidifirst and Stulz are the two major players in the Ultrasonic Humidification industry, and neither seem to have engaged in any serious marketing strategies like trade shows.

From Stulz

An average computer room with 10 air conditioners using an infrared humidification system will draw about 96 kw/h or 9.6 kw/h per air conditioner for humidification only. At a cost of $0.08 per kw/h, the energy cost of this system at an average yearly operation of 3,000 hours is $28,000. By comparison, for this computer room, 10 STULZ DAH 16 Ultrasonic humidifiers will draw only 4.95kw/h or 0.495kw/h per Humidifier at an approximate cost of $1,485 per year.

In this example, the STULZ system saves $26,515 on energy costs alone. Typical payback periods are 18 months.  If using 10 STULZ DRH 16 Ultrasonic humidifiers the draw would be 5.65kw/h or 0.565/h per Humidifier at an approximate cost of $1,695 per year.  In this example, the STULZ system saves $26,305 on energy cost alone.  Typical payback periods are 18 – 24 months for this system.

We spoke with Xcel Energy in Colorado, and what they had to say did jive with Stulz's claim, more or less:

Humidity controls (in data rooms) – The key here is not to over control.  Servers do not require tight humidity control…  Ultrasonic humidification is the best option, as it uses less energy, requires less maintenance.

Eager to bypass the marketing hype and perform our own analysis for DataCenterFix.com readers, we dove in head first into engineering manuals from both vendors (Humidifirst and Stulz), as well as CRAC unit vendors Liebert and Stulz.

Ultrasonic Humidification and LEED

It is possible to earn LEED points by making the switch from isothermal humidification in your data center to Ultrasonic Humidification. Some possible areas to earn LEED points:

lEAc1   Optimize Energy Performance – can help get points (up to10) by increasing building efficiency 38+% (retrofit) or 45+% (new)
lWEc3.1   Water Use Reduction – 1 point to help reduce building city water usage by 20%
lEQc3.2   A point for helping IAQ (RH%)
lEQc7.1/7.2   A point each for helping design and verify thermal comfort RH%

Ultrasonic Humidification Electrical Usage Comparison

Standard Liebert CW CRAH Humidification (Liebert CW 076-114 Models)

Ultrasonic Humidifiers by Stulz

* All Data Taken from Corresponding Engineering Manuals
¹ Stulz's largest single module is 17.6 lbs/hr. This example requires (1) 17.6 and (1) 4.4 lbs/hr units. In a data center environment with many CRAHs, the humidifier:CRAH ratio is lower

From this, we can see that using ultrasonic humidification uses approximately 92.6% less electricity than infrared humidification and 90.1% less electricity than steam generating humidifier canisters.

Before you jump to buy ultrasonic humidifiers, there are other factors you should consider. Ultrasonic humidifiers are more costly than traditional humidification systems. They requiree very clean water using either Reverse Osmosis or Deionization. Your water supply line(s) will need to be stainless steel or non-leaching PVC.

The best payback periods occur when starting from scratch with a new facility, but legacy data centers can still benefit. By installing an ultrasonic humidification system, you can disable the humidifiers in your CRAC and CRAH units. Who wouldn't want to save 93%?

^* The intenet of this article is not to pit any particular brand against another. No CRAC unit manufacturer today integrates an ultrasonic humidification solution within a CRAC unit cabinet. All CRAC unit brands have a steam generating humidifier system available, and Liebert is the only brand that offers infrared humidification.