Abstract: A thermally insulated substrate, e.g. a system of pipes, is maintained above a selected minimum temperature by means of one or more electrical heaters, preferably elongate self-regulating heaters. Each heater is successively switched on for a heat-up period and then off for a cool-down period. The durations of these periods are successively determined by reference to the ambient air temperature adjacent the substrate at an earlier time, e.g. at the end of the previous cool-down period. The method is particularly useful for temperature-maintenance systems in which a number of heaters are used to heat a complex system of pipes. The durations of the heat-up and cool-down periods for each heater (or for a group of two or more heaters) are separately determined by means of a single microprocessor.

Abstract: A system and method is disclosed for providing a continuous supply of clean air at a desired temperature to the crew compartment of a vehicle when in an environment contaminated by nuclear, biological or chemical warfare agents. Exhaust gases from the vehicle's engine is used to drive a first compressor which directs compressed and heated air to a precooler, an aftercooler, a heat exchanger and a pressure swing adsorption system which removes all known contaminates from the air providing clean output air. The clean air is expanded and cooled by a turboexpander which drives a secondary compressor and a coolant air compressor. A temperature controlled circuit is provided to control the temperature of the air throughout the circuit and in the crew compartment at the desired levels.

Abstract: A system and method provides a continuous supply of clean air at a desired temperature to the crew members of a combat vehicle when in an environment contaminated by nuclear, biological or chemical warfare agents. The contaminated air is initially compressed by energy received from the exhaust gases from a combustion power unit of the vehicle, the initially compressed air is then cooled to increase its density and is then compressed and cooled a second time before being passed through a pressure swing adsorbent system which continuously removes all known contaminants from the air, and is then expanded and changed in temperature to provide clean air at a desired temperature to personnel within the vehicle. The energy released from the air during expansion is used to compress the air the second time thereby providing a very energy efficient system.