Abstract: An apparatus (e.g., tube sheet) includes a plate piece, a sleeve piece, and a tube piece. The plate piece defines a hole. The sleeve piece has first and second ends; the second end is shaped to fit through the hole for attachment of the sleeve piece to the plate piece. The tube piece also has first and second ends. Inner and outer cross-sectional geometries of the tube piece and the sleeve piece (e.g., in the case of round tubes, inner and outer diameters) are shaped for the first end of the tube piece to fit in the first end of the sleeve piece and to form a continuous interior fluid flow path from the second end of the tube piece through the plate piece when the sleeve piece is disposed in the hole and attached to the plate piece and the tube piece is disposed in the sleeve piece.

Abstract: Various methods and systems are provided for an exhaust gas cooler. In one example, a method includes controlling a flow of coolant to at least a first stage of a plurality of stages of an exhaust gas cooler relative to a second stage of the plurality of stages to maintain at least one of: a controlled amount of heat removal from the first stage relative to the second stage, an about equal coolant temperature increase across the first stage relative to the second stage; an about equal gas temperature decrease across the first stage relative to the second stage; and an about equal gas heat removal across the first stage relative to the second stage.

Abstract: Various methods and systems are provided for an exhaust gas cooler. In one example, a method includes controlling a flow of coolant to at least a first stage of a plurality of stages of an exhaust gas cooler relative to a second stage of the plurality of stages to maintain at least one of: a controlled amount of heat removal from the first stage relative to the second stage, an about equal coolant temperature increase across the first stage relative to the second stage; an about equal gas temperature decrease across the first stage relative to the second stage; and an about equal gas heat removal across the first stage relative to the second stage.

Abstract: An apparatus (e.g., tube sheet) includes a plate piece, a sleeve piece, and a tube piece. The plate piece defines a hole. The sleeve piece has first and second ends; the second end is shaped to fit through the hole for attachment of the sleeve piece to the plate piece. The tube piece also has first and second ends. Inner and outer cross-sectional geometries of the tube piece and the sleeve piece (e.g., in the case of round tubes, inner and outer diameters) are shaped for the first end of the tube piece to fit in the first end of the sleeve piece and to form a continuous interior fluid flow path from the second end of the tube piece through the plate piece when the sleeve piece is disposed in the hole and attached to the plate piece and the tube piece is disposed in the sleeve piece.

Abstract: Various methods and systems are provided for an auxiliary power unit. In one embodiment, an auxiliary power unit comprises a plurality of independent modules configured to be installed in respective different locations within a rail vehicle or other vehicle. Each module of the plurality of independent modules is configured to carry out one or more respective functions of the auxiliary power unit for providing auxiliary power in the vehicle.

Abstract: Various methods and systems are provided for an auxiliary power unit. In one embodiment, an auxiliary power unit comprises a plurality of independent modules configured to be installed in respective different locations within a rail vehicle or other vehicle. Each module of the plurality of independent modules is configured to carry out one or more respective functions of the auxiliary power unit for providing auxiliary power in the vehicle.