Tested Energy Efficiency Technology Hybrid-ECU (TEETH)

Air Flows through TEETH into the deployable shelter.

Challenge

Increasing air conditioner operational efficiency beyond that of today’s improved environmental control units (IECUs) will effectively reduce fuel consumption on deployed bases. In cooling mode, IECUs work harder during peak load demand times (daytime) due to higher ambient temperatures, leading to greater energy consumption at peak load costs. Reducing/shaving peak air conditioning electricity load demands will reduce both energy and fuel consumption and the number of power generators deployed.

Solution

ARA leveraged previous experience developing phase change material (PCM) thermal storage technology for the U.S. Defense Department’s Environmental Security Technology Certification Program (ESTCP) to design and manufacture the Technology Readiness Level 7 (TRL 7) TEETH prototype. ARA’s SMART-Energy (SMART-E) group designed and fabricated a custom heat exchanger, insulated enclosure, airflow paths, and governing control system that automatically managed daily TEETH operation.

In August 2015, the SMART-E group successfully demonstrated the TRL 7 TEETH at Tyndall Air Force Base, FL, where it consistently shifted 6 hours of peak ECU operation to a 5-hour off-peak period, reducing peak ECU energy use by 75%. TEETH also improved shelter comfort conditions by maintaining a more consistent shelter temperature and reduced humidity levels. While TEETH was designed to mitigate the peak period ECU load, ARA recognized TEETH’s potential to reduce daily ECU energy consumption by 10% by exploiting increased ECU efficiency during late night and early morning hours. 

Using analytical and real-world data from the TRL 7 demonstration, ARA advanced the design to the TRL 8 stage and plans to demonstrate the more compact and efficient TRL 8 TEETH prototype in the summer of 2016. Looking forward, plans are to advance the technology with a novel heat exchanger design that significantly expedites PCM regeneration during off-peak hours, resulting in 30% daily ECU energy savings.

Impact

Integrating the TEETH unit into the HVAC system reduces ECU power demand and shifts it to off-peak hours. TEETH also provides more comfortable shelter conditions. Shifting and reducing peak ECU operation is critical for minimizing energy consumption and reducing use costs. Previous demonstrations have shown that peak shaving with this system can eliminate one 750 kW generator for a 3,300-person deployment.  

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