Exhaust gas
Inlet air to the tested propulsion systems can be conditioned up to 450 degrees Fahrenheit by large combustion air heaters. These heaters can burn either diesel fuel or waste aviation fuel and generate up to 1,000,000,000 BTU per hour. Exhaust gases are cooled by direct-contact water spray, which reduces the temperature to 200 degrees Fahrenheit. Additional water spray cools and cleans the exhaust gas to less than 150 degrees Fahrenheit before it enters the exhaust compressors.