Abstract: A system is disclosed for dispensing fuel into the transient flow of an exhaust system to control exhaust emissions. A controller initiates the delivery of fuel into the exhaust when an emissions control device, such as a diesel particulate filter, requires increased exhaust temperatures for regeneration. In operation, pressurized fuel and pressurized air are supplied to a fuel delivery device, wherein a fuel injector pre-mixes fuel with air. The fuel-air mixture is then dispensed into the exhaust flow through a nozzle, causing a rapid pressure drop in the mixture that results in the pressurized air expanding rapidly, breaking the fuel spray into fine particles.