TILLSATSVERMEAPPARAT FOR FORDON

摘要

An auxiliary heater device comprises a tubular combustion chamber surrounded by a heat exchanger 50 as to define a gap therebetween. The peripheral wall of the combustion chamber is provided with a plurality of circumferential projections that extend into the gap in a manner that reduces direct contact heat exchange between the combustion gases flowing through the gap and the peripheral wall by blocking axial flow of the gases along the wall in contact therewith and by deflecting these gases toward the heat exchanger pipe.