Abstract: An EGR cooler including tubes and a shell enclosing the tubes. Cooling water is supplied into and discharged from the shell. Exhaust gas is guided from a diesel engine into the tubes for thermal exchange of the exhaust gas with the cooling water. A bypass flow path for guiding the cooling water is constituted within the shell so as to prevent stagnation of the cooling water in the shell.

Abstract: An EGR cooler including tubes and a shell enclosing the tubes. Cooling water is supplied into and discharged from the shell. Exhaust gas is guided from a diesel engine into the tubes for thermal exchange of the exhaust gas with the cooling water. A bypass flow path for guiding the cooling water is constituted within the shell so as to prevent stagnation of the cooling water in the shell.

Abstract: A reactor, comprising an inner reaction tube, a head part having an inlet for feed, and an outer cylindrical part having a space to accommodate therein the inner reaction tube and an outlet for product, wherein the head part is connected to the outer cylindrical part and the inner reaction tube placed in the space of the outer cylindrical part is also connected to the head part and/or the outer cylindrical part. This reactor can be easily assembled or disassembled; that is, a catalyst placed in the inner reaction tube can be exchanged only by dismantling one of the head part and the outer cylindrical part. Thus the reactor of the invention is suitable for use in chemical experiments.