Aspen Systems, Inc. Develops Environmental Control Unit (ECU-Chill®)


ASI has developed a new environmental control unit (ECU) named “ECU-Chill®” to provide cooling to military enclosures and transit cases that enables operations in high-temperature environments, while dissipating the increased heat loads generated by military electronics. The objective of this program was to develop a refrigeration based environmental control unit for electronics enclosures with the capability to dissipate over 500 watts of heat while maintaining internal air temperatures at or below outside ambient levels. Additional objectives included; a heating capability for cold start up, sealing the electronics from environmental contamination, and meeting environmental requirements for military systems.

Army Need:

The Army’s demand for state of the art Command, Control, Communications and Computers, Intelligence Surveillance and Reconnaissance (C4ISR) systems has risen dramatically in recent years. These high band width systems have become increasingly complex and sophisticated to meet the need for communications and computing power in mobile systems. The newer systems produce much higher levels of heat than their forerunners and as a result are difficult to keep operational in the CENTCOM Theater of Operations. Thermal overrun temperatures are the single leading cause of electronics failures and MTBF availability issues. The dissipation of elevated levels of heat from these advanced electronics systems has proven to be difficult to overcome with standard thermal management techniques. This has grown to be a critical issue since these systems must be deployed to very high ambient temperature environments. New, thermal management systems with the ability to cool enclosures below ambient temperature are required to keep these systems operational.

Furthermore, many new and legacy systems utilize Commercial-Off-the-Shelf (COTS) rack mounted electronics that were originally designed for operation in air conditioned office buildings. These rack mounted systems are now deploying in transit cases that are exposed to ambient temperatures exceeding 120°F, cold, rain, sand, and dust typical of a military environment. The environmental control unit, “ECU-Chill” developed under this program is a mission enabler for the fielding of COTS and high-end C4ISR electronics systems, by providing a clean, cool, sealed environment that helps ensure their reliable operation in severe environments.


ECU-Chill is a vapor compression refrigeration system that consists of Aspen’s unique, miniature rotary compressor, condenser, evaporator, fans, control system, expansion valve, heater, and refrigeration lines. ECU-Chill is a complete ruggedized environmental control unit that provides cooling or heating as determined by the internal temperature of the enclosure. It maintains a sealed electronics enclosure at or below ambient temperatures, enabling Commercial-Off-The-Shelf (COTS) and advanced C4ISR electronics to be safely and effectively used for computing and communications in extremely hot or cold environments. At temperatures below 40°F (4.4°C) ECU-Chill provides 300 Watts of heat. Between 40°F and 80°F (26.6°C) there is no cooling or heating, and above 80°F the compressor and condenser fans operate and 550 Watts of cooling is provided.

The system has been fully ruggedized for military use to MIL-STD 810. ECU-Chill will continuously maintain a temperature of ≤125°F (51.6°C) inside an electronics enclosure in a 125°F ambient environment while dissipating 550 Watts of waste heat. The electronics remain sealed against all environmental contamination, improving reliability. At less than 20 pounds, the ECU-Chill system can be deployed in transit cases while maintaining the two man lift mobility requirements. This compact ECU measures 18.5 inches wide by 9 inches high, and 6.7 inches deep. Combined with its low weight, ECU-Chill maximizes enclosure designer’s freedom to increase power while maintaining a minimum enclosure size and weight. ECU-Chill has met its rating specifications during all aspects of MIL-STD 810, including operation in blowing sand and dust.

To assure an even temperature distribution and an accurate temperature reading inside the transit case, the internal evaporator fans run whenever the ECU is powered up. The system can be mounted to the cover or side wall of an electronics enclosure or transit case. A power cord is provided to accept 28 VDC power. A temperature sensor in the ECU monitors enclosure temperature and provides feedback to the ECU control system. The internal controls then varies the compressor speed to maintain desired enclosure temperatures. Visual and audible alarms indicate ECU operational status. A toggle switch for disabling the alarm and LED is provided.

Phase III Impacts:

The SBIR program was combined with Phase III contracts to fully develop the ECU-Chill system into a field-ready system. ECU-Chill is now in production at Aspen’s facility in Marlborough, MA. ECU-Chill is beginning to be used by a major Army program with ECU systems being procured for two different systems. SOCOM is using the ECU-Chill on its MRAP variant to cool C4I equipment.

To date Aspen has received over $7.2M in production orders for ECU-Chill. It is anticipated that this product will expand its operational presence onto numerous programs to provide ECU capabilities to more effectively field C4ISR and rack mounted electronics in mobile Army applications.