Proton Exchange Membrane Fuel Cell (PEMFC) is majorly used for power generation without producing any emission. In PEMFC, the water generated in the cathode heavily affects the performance of fuel cell which needs better water management. The flow channel designs, dimensions, shape and size of the rib/channel, effective area of the flow channel and material properties are considered for better water management and performance enhancement of the PEMFC in addition to the inlet reactant's mass flow rate, flow directions, relative humidity, pressure and temperature. With the purpose of increasing the output energy of the fuel cell, many flow field designs are being developed continuously. In this paper, the performance of various conventional, modified, hybrid and new flow field designs of the PEMFC is studied in detail. Further the effects of channel tapering, channel bending, landing to channels width ratios, channel cross‐sections and insertion of baffles/blockages/pin‐fins/inserts are reviewed. The power density of the flow field designs, the physical parameters like active area, dimensions of channel/rib, number of channels; and the operating parameters like temperature and pressure are also tabulated.

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Pipe bending by high-frequency local induction heating is an advanced technique used to bend pipes having a small bending radius and a large diameter. Although pipe bending is a widely used engineering process, the optimum process parameters are decided on the basis of a trial and error method by highly experienced field engineers. Hence, it is necessary to develop an integrated methodology for the optimum design of the pipe bending process. During hot-pipe bending using induction heating, the thickness of the outer wall of the pipe decreases because of tensile stress, but the thickness is not allowed to decrease by more than 12.5%. The use of the DOE method and a dynamic reverse moment is proposed for maintaining the thickness reduction ratio to within 12.5%, when D/t is high. The results of the proposed approach are found to be in good agreement with those of FEA.

The liner of a CNG pressure vessel is manufactured by a DDI (deep drawing and ironing) process for the cylinder part, which is a continuous process that includes a drawing process to reduce the diameter of the billet and a subsequent ironing process to reduce the thickness of the billet. A tractrix die used in the 1st deep drawing allows the blank to flow smoothly by decreasing the punch load and radial tensile stress occurring in the workpiece. It also increases the draw ratio compared to conventional dies, but it causes forming defects. In this study, a shape coefficient (Sc) is proposed for the tractrix die using the blank diameter (D0), inflow diameter of the workpiece (di), and inflow angle of the workpiece ($$\theta$$ θ ) for design of the tractrix die. The effects of the thickness and inflow angle of the workpiece on wrinkling and folding were investigated through FEA. Also, a discriminant is proposed for the relative radial stress ($$\tilde{\sigma }$$ σ ~ ) generated during the deep drawing process using the tractirx die and used to predict fracture. Based on the results, the blank thickness, the draw ratio, and the inflow of the workpiece angle in the 1st deep drawing process are suggested, and the number of operations in the DDI process was reduced from 6 to 4. This improves the productivity and reduces the manufacturing cost.