Main Page | See live article | Alphabetical index FRH is an abbreviation for "flameless ration heater," an water-activated exothermic chemical heater included with Meals, Ready-to-Eat (MREs), used to cook the food. US military specifications for the heater require that it be capable of raising the temperature of an eight-ounce entree by 100°F in twelve minutes, and that it display no visible flame. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.