New ETF service air system is now more energy efficient for AEDC operations

  • Published
  • By Janaé Daniels
  • AEDC/PA
Arnold Air Force Base, Tenn. --  Arnold Engineering Development Center (AEDC) is always looking for ways to conserve the cost of energy. 

Although it was not initiated as an energy-cost savings project, replacing the Engine Test Facility (ETF) Service Air System has already seen energy-cost savings. The new system will implement a consolidated service air plant for the propulsion mission area. 

A cost analysis was done at the end of fiscal year 2009 dollars to estimate what the energy cost savings would be. 

"If the system was completely finished and operational today, the cost savings would be estimated at around $535,000 a year, with about 84 percent of these savings being energy-related," Brandon Lucy, 651st Test Systems Squadron program manager, said. "This is very good for our investment projects. Sometimes it's hard to quantify our paybacks because the requirements are not driven by payback like a private company and their profits, but for us it's by keeping the center viable for our test customers." 

Even though the project will not be complete until 2011, Lucy says this estimation is fairly close to the actual outcome. 

"We are really going to get close to that $535,000 even though at the completion of this year's work we will only have seven of the 11 operational compressors," he explained. "We are now able to take two of the old large high energy use compressors off line, when not needed for testing and rely exclusively on the new energy efficient compressors." 

According to Mike Harvey, Aerospace Testing Alliance (ATA) system engineer for the ETF Service Air System, the system will consist of 11 Ingersoll Rand rotary screw-type air compressors distributed in two locations, C-Plant/Compressor, building 913 and B-Plant/ETF Air Compressor and Test, building 878. 

The new integrated system also employs desiccant dryers, both wet and dry air receivers for storage, filters, oil water separators and demand driven control to only provide air as the downstream use requires. 

The service air system provides 90 to 125 psig air throughout ETF for pneumatic tools and maintenance work (shop air), all pneumatic operated valves and other services and some test support activities such as engine starts and test cell air curtains. 

The procurement portion of the project began in 2007 and is being implemented in five phases for a total cost of $5.5 million. This procurement supplies demolition of the old equipment and supply and installation of the new equipment. At the end of fiscal year 2009, three of the five phases have been completed. 

According to Lucy, the goal of the project is to eliminate old legacy, high-energy usage compressors that have aged, require continuous maintenance and have caused lost test time. 

"The compressors in the B and C plants will be demolished and be replaced with a total of 11 energy efficient screw-type compressors. At this time we have installed seven. The remaining four will be installed by fiscal year 2011." 

In the past, there were multiple service air compressors distributed throughout ETF, over time those all were connected into a common header, but the systems were not integrated or set up to talk to each other. Lucy said this was another cause of high-energy usage because compressors would be operating essentially all the time. 

"When the system engineers took a total look at the system, through the design efforts, they said we needed to move to something more energy efficient," he said. "Instead of a couple of large compressors, we needed to move to smaller, more energy efficient ones." 

Fred Hutchinson, ATA Investments and Design project manager, said storage was added to the project as well. 

"This is something we didn't have before two 20,000-gallon storage vessels, storing extra air that is built up to support large step-change demands without compressor ignition," Hutchinson explained. "It also provides some air service when all compressors are shut down." 

A similar system was replaced in the von Kármán Gas Dynamics Facility (VKF) in 2005. 

"The new VKF Ingersoll Rand Service Air Compressor system replaced an existing Ingersoll Rand system, installed in 1989, that was oversized and not energy efficient," Mike Hollis, system engineer for the VKF service air compressor system, explained. 

"Due to this system being oversized, there were operational problems which caused compressor surges. With the original system, there were some AEDC testing impacts. Also, the original system required extensive maintenance costs compared to the new. Maintenance on the original system was done in-house and required an extensive spare parts inventory in the warehouse. Maintenance on the new system is contracted to Ingersoll Rand, a Nashville Service Center, rather than in-house maintenance. This results in no in-house maintenance costs or spare parts inventory costs to AEDC." 

According to Hollis, the initial cost analysis of the new system showed a return on investment of 15 months due to power costs savings. 

"This analysis prompted the Air Force to fund $227,000 for purchase and installation of the new compressors, dryers, air storage vessels and other equipment," Hollis said. "To date there have been no operational impacts to AEDC testing with the new system." 

This new VKF system won the Association of Energy Engineers 2006 Middle Tennessee Energy Award due to the energy savings. The redesigned system provides greater reliability, reduced operating costs and built-in redundancy. Annual energy savings are estimated at 1,770,000 kilowatt hours for more than $171,700. 

The success of the VKF Plant system and the lessons learned were valuable inputs for the designers of the new ETF Service Air System. 

Similar to the VKF Plant, the ETF Service Air system is also being maintained on a service agreement with Ingersoll-Rand allowing the same maintenance cost savings to be realized.