Disclosed is an improved method of manufacturing cooled accelerator grid with full penetration weld configuration. In a preferred form, the method includes the steps of: machining a plurality of stubs, a first and a second end of a plurality of inconel pipes; welding the stubs with the first end of the inconel pipes forming a water connector assembly; machining of a base plate; welding the base plate with the water connector assembly; machining the base plate welded with the water connector assembly, wherein machining further comprises milling of plurality of cooling channels across angled plane of the base plate welded with the water connector assembly; closing of plurality of cooling channels located on the base plate welded with the water connector assembly; and welding each of plurality of external hydraulic circuits with the second end of each of the plurality of inconel pipes.

A heat transfer tube fixing apparatus of a heat transfer tube expansion apparatus has grasping sections and a moving section. The grasping sections grasp one axial direction end sections of a plurality of heat transfer tubes in a state where the heat transfer tubes are inserted in a plurality of heat transfer fins. The moving section switches between a first state of covering the surroundings of the grasping sections and a second state of not covering the surroundings of the grasping sections by moving in the axial direction of the heat transfer tubes. The grasping sections fix the heat transfer tubes so as not to move in the axial direction and the heat transfer fins and the heat transfer tubes are fixed by the heat transfer tubes expanding in a state where the moving section is in the first state.

This invention relates to an apparatus, comprising: a plurality of plates in a stack defining at least one process layer and at least one heat exchange layer, each plate having a peripheral edge, the peripheral edge of each plate being welded to the peripheral edge of the next adjacent plate to provide a perimeter seal for the stack, the ratio of the average surface area of each of the adjacent plates to the average penetration of the weld between the adjacent plates being at least about 100 cm.sup.2/mm. The stack may be used as the core assembly for a microchannel processor. The microchannel processor may be used for conducting one or more unit operations, including chemical reactions such as SMR reactions.

A heat exchanger includes a plurality of plate-shaped fins arranged at intervals such that air flows between adjacent fins, each of the fins having insertion holes and a plurality of flat tubes extending through the fins such that a refrigerant flows through the tubes in a stacking direction of the fins, each flat tube having a cross-section having straight long sides and half-round short sides, each flat tube having long-side outer circumferential surface parts and a short-side outer circumferential surface part in contact with the fin and covered with the brazing filler metal. The fins and the flat tubes are joined with the brazing filler metal covering the outer circumferential surfaces of the flat tubes such that top part of each fin collar of each fin is in contact with the flat tube and base part of the fin collar is spaced apart from the flat tube.