flash boiler

A variety of water-tube steam boiler, used chiefly in steam automobiles, consisting of…A variety of water-tube steam boiler, used chiefly in steam automobiles, consisting of a nest of strong tubes with very little water space, kept nearly red hot so that the water as it trickles drop by drop into the tubes is immediately flashed into steam and superheated. (This type of boiler allowed steam autos to steam up fast enough to be practical.)