Ultrasonic Humidification for Commercial Buildings
Humidification: Ultrasonic vs. Electric Resistance
Ultrasonic humidifiers add moisture to the air without heating the water by injecting ultrasonic pulses into the water, vibrating water molecules at high speeds. This overcomes molecular forces and allows microscopic water molecules to escape.
Item ID: 121
HVAC--Other HVAC Systems
Technical Advisory Group: 2009 HVAC TAG (#2)
Technical Advisory Group: 2013 Information Technology TAG (#8)
Average TAG Rating: 1.92 out of 5
TAG Ranking Date: 10/25/2013
TAG Rating Commentary:
- Good idea, however goal is to reduce humidification requirements (e.g. increase humidity range)
- If allowable environmental conditions are used, humidification is not needed at all.
- This is an ET.
- Humidity control is not important in data centers
- Shouldn’t need to humidify air in Pacific NW
An air humidifier is the general term for a device designed to increase the moisture content of an air stream. Traditionally, air humidifiers in commercial HVAC systems have used resistance heat to turn liquid water into vapor which could then be introduced into the air to be conditioned. Humidifiers which rely upon non-heat driven evaporative forces also exist, functioning primarily by means of air blown through a moistened absorbent material. Another option is the ultrasonic humidifier, which uses a rapidly vibrating piezoelectric element to project micrometer-sized water droplets into the air, where they are quickly absorbed. Although ultrasonic humidifiers are more common on residential applications, they are still fairly uncommon in existing commercial sector applications. Another non-evaporative technology uses a high-speed rotating impeller to generate cool mist.
Ultrasonic humidifiers use approximately 90% less energy to perform comparable amounts of humidification as a resistance heat-driven humidifier. In a cooled space, ultrasonic humidifiers can have a cooling effect via adiabatic processes, whereas steam humidifiers actually increase the latent heat content of the air. One disadvantage of non-evaporative humidifiers is that in addition to water, they have been shown to project micro-organisms or minerals from the water supply into the air. To prevent this, buildings with water quality issues should employ a form of pure water. Water with a higher mineral content can cause scale that breeds microorganisms, so when using non-evaporative humidifiers it is advisable to obtain a water supply using distillation (the best method), deionization, or reverse osmosis; alternatively, a demineralizing filter may be used.
Ultrasonic humidifiers generally have a higher up-front cost than steam humidifiers. However, their low, ongoing operating costs and other advantages have made them more common for most new construction of the types of buildings that need to maintain a certain level of humidity, such as data centers, printing houses, bakeries, dairies, labs and sensitive manufacturing facilities.
Baseline Description: 1 pound of 55 degree water converted to steam for humidification
Baseline Energy Use: 8.5 kWh per year per unit
From steam tables, 180 Btu/#, for 1# from 55 to 212 = 28,260 Btu. 212 degree water to steam is 970 Btu/# = 29,000 Btu = 8.5 kWh
Manufacturer's Energy Savings Claims:
"Typical" Savings: 98%
Stultz (Airwin, 2013)
Best Estimate of Energy Savings:
"Typical" Savings: 90%
Low and High Energy Savings: 90% to 93%
Energy Savings Reliability: 5 - Comprehensive Analysis
The United States Department of Energy (US DOE), Federal Energy Management Program (FEMP) (US DOE, 1999) states the energy savings is 90% to 93% for ultrasonic humidifiers versus steam generators.
Energy Use of Emerging Technology:
.9 kWh per unit per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Potential number of units replaced by this technology:
In order to provide electrical energy savings, the new humidifier must replace an existing humidifier in which electric resistance heat is used to generate steam. Electrical energy savings will not occur and only fuel savings will be captured (in fact, electrical energy use will increase) when this technology is used to replace humidifiers that inject steam into conditioned air flows. Humidifiers are commonly found in hospitals, art museums, industrial facilities and computer rooms. Note that electric steam humidifiers are used when a source of steam is not available. Industrial plants (such as textile spinning mills) and hospitals generally have operable steam systems so no electrical energy savings are available from these facilities.
Absent a comprehensive regional market survey, technical energy savings cannot be estimated, but are thought to be small in the commercial and industrial sectors.
Regional Technical Potential:
0.00 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Currently no data available.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.