NOVELTY - The exchanger (1) has first and second heat exchange sections (2, 3) located within first and second housings (5, 4) adjacent to each other. A first set of heat exchange tubes (9) traverses the first heat exchange section. A second set of heat exchange tubes (8) traverses the second heat exchange section. An exhaust gas flow path comprises first fluid volume (7) and interiors of the second set of the heat exchange tubes. A coolant flow path comprises second fluid volume (6) and interiors of the first set of heat exchange tubes, where the fluid volumes are partially enclosed by the housings.    USE - Exhaust gas heat exchanger for transferring heat from an exhaust gas flow to a liquid coolant in an internal combustion engine i.e. diesel engine, of a power generation system in vehicles, construction equipments and stationary power generating devices.    ADVANTAGE - The exchanger allows a cartridge to be constructed as a brazed or welded subassembly that is inserted into the first housing such that the heat exchange tubes and a return manifold can be inserted through an aperture provided in a wall section of the first housing and an end of the cartridge with coolant manifolds can be joined to the wall section, so that the coolant manifolds can be located within the wall section, thus providing added benefit of cooling of the wall section, and hence minimizing structural loading to be imposed upon a header through thermal expansion of the first housing, while minimizing size and weight of the exchanger. The exchanger allows the cartridge to be made to be replaceable in an event of failure e.g. coolant leak, occurring within the cartridge by grinding away welds that secure the cartridge to the wall section, thus avoiding a need to replace entire exchanger. The exchanger allows coolant ports to be provided at common ends of the heat exchange tubes and the return manifold to be provided at opposing ends such that the heat exchange tubes can be made to be thermally unconstrained within the first housing, so that stresses within the heat exchange tubes from differential thermal expansions between the first housing and the heat exchange tubes can be lessened, thus increasing durability of the exchanger. The exchanger allows the heat exchange tubes to be provided with twisted embossments within tube walls to provide beneficial turbulation of the coolant passing through the heat exchange tubes and exhaust gas passing over the heat exchange tubes, thus improving heat transfer performance within the exchanger, while reducing likelihood of structural failures.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for recirculating flow of exhaust gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional perspective view of an exhaust gas heat exchanger.    Exhaust gas heat exchanger (1)    Heat exchange sections (2, 3)    Housings (5, 4)    Fluid volumes (6, 7)    Heat exchange tubes (8, 9)