In these recuperatorsthe calorific power transfer between the primary and secondary fluids is basically made by radiation.
Double shell recuperators offer a lower fuel consumption, even over 40%, because of a combustion air pre-heating and a compact design which allows their installation in the fumes stack.
They are made of two concentric cilinders in which the secondary fluid flows through the circular crown, either in parallel to the recuperator axis or helicoidally, counterflow or in paralell drafts.
Appropriate for working pressures up to 2.000 mm W.G.
For higher working pressures the ring arranged tubes cage recuperators offer a better performance, a higher resistance and a more homogeneous air distribution.
They are designed replacing the interior shell by a ring arranged tubes cage, through which the air flows, so that the heat transfer is still made by radiation.