A crew cooling system for the M9 Armored Combat Earthmover (ACE)

This paper describes the development and testing of a vapor-compression cooling system for the M9 Armored Combat Earthmover (ACE). The M9 ACE is an 18-ton, fully tracked vehicle designed for combat engineer tasks to ready and maintain the forward battle area for offensive or defensive operations. The M9 ACE has a single crew member in a very small compartment that is exposed to ambient conditions. Due to the proximity of this compartment to the air exhaust from the engine´s cooling system, ambient temperatures in the crew compartment can cause heat stress and other physiological problems for the crew. An HFC-134a vapor-compression cooling system was designed to chill water that is circulated through a cooling garment worn by the crew. The cooling system is powered by the vehicle´s 24-volt electrical power, is capable of rejecting heat to 150°F ambient air, and can withstand the vibration, shock, and other conditions of the battlefield. Two generations of this cooling system were designed, fabricated, lab-tested, and field-tested on the M9 ACE. This paper describes the system and its components in detail, and presents the system performance results from the lab tests and field tests