surface will not be a single face but rather will be formed by discrete portions e g edge portions of plates the rotation of the core brings heat transfer portions of the core 130 sequentially through the exhaust gas flowpath and the inlet air flowpath the exemplary heat exchanger is positioned so that the heat exchange is counterflow i e the exhaust flow and air inlet flow are in opposite directions as so far described the system is illustrative of just one of a variety of plant configurations to which the present invention may be applied according to the present invention one or more detonative cleaning systems may be located along the air combustion products flowpath and positioned to clean the element fig3 and 4 show an exemplary cleaning system 220 the exemplary system 220 includes a plurality of pulsed combustion devices 222 and 223 in the exemplary implementation two devices are shown the first device 222 being upstream of the core along the exhaust flowpath and the second device 223 being downstream of the core along the exhaust flowpath each device 222 223 has a conduit 224 having an outlet 226 at one end in interior 228 of the housing 120 and facing an associated core axial end 150 152 exemplary combustion conduits have lengths of 0 5 4 m and cross sectional areas of 20 730 cm 2 the conduit 224 may include one or more inlets for receiving fuel and oxidizer fig2 shows exemplary fuel.