Method and device for controlling effective heat transfer in a solid gas storage system

摘要

A method for controlling the effective heat transfer from a storage unit (1). During gas release from storage material (3) in the storage unit the storage material is heated by a heater (2). During re-saturation of the storage material (3) with gas the heater is off. Controlling of the effective heat transfer from the storage unit (1) is performed, during gas release, by ceasing convection of a convection gas and, during re-saturation, by performing or enabling convection of a convection gas to cool the storage unit (1).

主权项

1. A device for controlled dosing of ammonia for reducing NOx from the exhaust of an internal combustion engine of a vehicle via selective catalytic reduction, said device comprising:
at least one start-up storage unit containing a solid ammonia storage material reversibly storing ammonia by absorption or adsorption, and desorption, the at least one start-up storage unit being equipped with a heater to release ammonia by desorption, at least one additional larger storage unit with ammonia storage material, the larger storage unit having a supply pressure generated by heating of the ammonia storage material in the larger unit, and a controller, said start-up storage unit further comprising:
a fluid gap between the at least one start-up storage unit and an encapsulation;a fluid flow device to control the flow of gaseous fluid through the gap between the at least one start-up storage unit and the encapsulation, or a passive-convection control shutter to control passive convection of gaseous fluid through the gap between the at least one storage unit and the encapsulation, the passive-convection control shutter arranged to selectively open and close a fluid-flow path including the fluid gap; the controller being programmed to carry out a method comprising:
during ammonia release from the ammonia storage material of the start-up storage unit, heating the storage material by a heater, and controlling effective heat transfer from the start-up storage unit during ammonia release, by ceasing operation of the fluid flow device, or by regulating convection created by the fluid flow device such that it is lower than that during re-saturation, or by disabling passive-convection by means of the passive-convection control shutter; andre-saturating the start-up storage unit comprising performing immediately after use of the start-up storage unit when the vehicle is parked, saturation of the storage material with ammonia delivered from the larger storage unit by heating the larger storage unit, the heater of the start-up storage unit being off, and controlling effective heat transfer from the start-up storage unit by operating the fluid flow device, or by regulating the convection created by the fluid flow device such that it is higher than during ammonia release, or by enabling passive-convection by means of the passive-convection control shutter thereby increasing the re-saturation rate of ammonia when ammonia is delivered from the larger storage unit.