Abstract:
A large-heat-input butt-welded joint of welded structures prepared by butt-welding high-strength steel plates over 50 mm in thickness, having excellent brittle fracture resistance, is characterized by: (a1) the hardness of the weld metal is not more than 110% of the hardness of the base metal or (a2) the hardness of the weld metal is not less than 70% and not more than 110% of the hardness of the base metal, and, as required, (b) the width of the weld metal is not more than 70% of the plate thickness of the base metal, (c) the width of the region affected by welding whose hardness is softened to not more than 95% of the hardness of the non-heat-affected base metal has a width not less than 5 mm, and/or (d) the prior austenite grain size in the heat-affected zone (HAZ) contacting the welding fusion line is not more than 200 μm.
Abstract:
A large-heat-input butt-welded joint of welded structures prepared by butt-welding high-strength steel plates over 50 mm in thickness, having excellent brittle fracture resistance, is characterized by: (a1) the hardness of the weld metal is not more than 110% of the hardness of the base metal or (a2) the hardness of the weld metal is not less than 70% and not more than 110% of the hardness of the base metal, and, as required, (b) the width of the weld metal is not more than 70% of the plate thickness of the base metal, (c) the width of the region affected by welding whose hardness is softened to not more than 95% of the hardness of the non-heat-affected base metal has a width not less than 5 mm, and/or (d) the prior austenite grain size in the heat-affected zone (HAZ) contacting the welding fusion line is not more than 200 μm.
Abstract:
A welding method for manufacturing welded structures having excellent properties to prevent the propagation of brittle fracture occurring in welded joints, characterized by the step of forming a repair weld having a greater toughness than that of a butt weld and an outer edge whose angle φ with respect to the longitudinal direction of the butt weld is not less than 10 degrees and not more than 60 degrees, by applying repair welding to a region to arrest a brittle crack in a butt-welded joint where a brittle crack is likely to propagate after removing part of the butt-welded joint, in said region, by gouging or machining.
Abstract:
A fuel cell system 10 of the present invention comprises a fuel cell 11, an ejector 15 which mixes an exhaust gas exhausted from the fuel cell 11 with a fuel gas, and circulating this mixed gas to the fuel cell 11, and a fuel humidifying section 16 for bringing the exhaust gas exhausted from the fuel cell 11 into contact with the fuel gas which is made to flow out from the ejector 15, via a water permeable membrane, to thereby humidify the fuel gas by the water content contained in the exhaust gas. The fuel humidifying section 16 is arranged between the fuel cell 11 and the ejector 15.
Abstract:
A humidifier 21 for use with a fuel cell 1, including a plurality of combined water permeable membranes or water permeable devices 21, each of the water permeable membranes or water permeable devices generating humidified gas by flowing therein different gases with different moisture contents and by moisture exchanging between the different gases so that one dry gas with smaller moisture content is humidified with the other moist gas with larger moisture content; and flowing passage switching devices Va for optionally switching flowing passages Ca of the dry gas. The flowing passage switching devices Va switches the flowing passage Ca in accordance with a required amount of the humidified gas so as to selectively use particular water permeable membranes or a particular water permeable device 21 from among the plurality of water permeable membranes or water permeable devices 21.
Abstract:
An effective volume Vep of a member is calculated with a stress correction amount σcorr added to an effective stress (stress amplitude) σip at each position of the member so that a fatigue strength of the member varying corresponding to an average stress varying depending on the position of the member is apparently constant at a value when the average stress on the member is 0 (zero) irrespective of the position of the member, and a cumulative fracture probability Pfp due to fatigue of the member is derived using the effective volume Vep of the member.
Abstract:
A fuel cell stack 1 in a fuel-circulating fuel cell system is supplied with fuel and an oxidizing agent to generate electricity. The fuel discharged from the fuel cell stack 1 is supplied to the fuel cell stack 1 again through a fuel-circulating passage 6. In the fuel-circulating passage 6 is provided a fuel pump 3 powered from an outside source to circulate the fuel through the fuel-circulating passage 6 at a predetermined circulation rate. An ECU 4 transmits an output instruction value to the fuel cell stack 1 and regulates a circulation rate of the fuel in the fuel-circulating passage 6 according to the output instruction value.
Abstract:
A fuel cell system includes a fuel cell for generating power by being supplied with a fuel gas and an oxidizing gas, a fuel gas supply path for supplying a fuel gas to the fuel cell, a fuel off-gas circulation path for returning a fuel off-gas discharged from the fuel cell to the fuel gas supply path, an ejector, provided in the fuel gas supply path and driven by fluid flow energy, for supplying the fuel off-gas in the fuel off-gas circulation path flow to the fuel gas supply path, a fuel pump, provided in the fuel off-gas circulation path or on the fuel gas supply path and downstream with respect to the ejector, and driven by a rotating machine, for pressurizing the fuel off-gas, a discharge valve for discharging the fuel off-gas from the fuel off-gas circulation path; and a control device operatively connected to the fuel pump and to the discharge valve.
Abstract:
A fuel cell includes an anode and a cathode, and a fuel gas supplied to the anode and an oxidant gas supplied to the cathode chemically react with each other to generate electricity. Moisture contained in a cathode exhaust gas discharged from the cathode is transferred to the fuel gas in a first humidifier and then to the oxidant gas in a second humidifier. The cathode exhaust gas flows through a cathode exhaust gas passage from the cathode via the first humidifier to the second humidifier. A bypass is provided to the cathode exhaust gas passage to allow part of the cathode exhaust gas to detour round the first humidifier and flow to the second humidifier. Accordingly, the balance between humidification levels of fuel gas and oxidant gas each supplied to the fuel cell may be kept and adjusted properly even when the output of the fuel cell gets higher.
Abstract:
A more compact humidifying apparatus for a fuel cell can be implemented. In the present invention, hydrogen humidifying modules 30A and 30B are disposed so as to be separated vertically on the front surface side of the humidifying unit 20, the air humidifying modules 30C and 30D are disposed separated vertically on the back side surface thereof, and the air humidifying modules 30E is disposed at the center, surrounded by the humidifying modules 30A, 30B, 30C, and 30D. The axis direction of all of the humidifying modules 30A to 30E are disposed so as to be parallel to each other, only the hydrogen humidifying module 30A is disposed so that its position is shifted to the left (the longitudinal direction) of the axial direction of the other humidifying modules 30A to 30E, and the air off gas discharge pipes 43 of the air humidifying modules 30C to 30E are disposed in the space formed by this shift.