Finite element comparison of single, bi-layered and three-layered tube hydroforming processes
In this paper, single, bi-layered and three-layered tube hydroforming processes were numerically simulated using the finite element method. It was found that the final bulges heights resulted from the models were in good agreement with the experimental results. Three types of modeling were kept with the same geometry, tube material and process parameters to be compared between the obtained hydroformed products (branch height, thickness reduction and wrinkling) using different loading path types. The results were also discussed.
Experimental study and finite element analysis of simple X- and T-branch tube hydroforming processes
The tube hydroforming process is a relatively complex manufacturing process; the performance of this process depends on various factors and requires proper combination of part design, material selection and boundary conditions. Due to the complex nature of the process, the best method to study the behaviour of the process is by using numerical techniques and advanced explicit finite element (FE) codes. In this work, X- and T-branch components were formed using a tube hydroforming machine and experimental load paths (forming pressure and axial feed) were obtained for the processes via a data acquisition system integrated with the machine. Subsequently, the processes were simulated using LS-DYNA3D explicit FE code using the same experimental boundary, loading conditions and the simulation results were compared with the experimental results. It was found that the developed branch height and the wall thickness distribution along different planes were in good agreement with the experimental results.
Techno-economic and exergetic assessment of an oxy-fuel power plant fueled by syngas produced by chemical looping CO2 and H2O dissociation
Abstract Natural Gas Combined Cycle (NGCC) is presently the most efficient fossil fuel power plant but with no carbon capture. The efficiency penalty resulting from the integration of carbon capture and storage (CCS) is, however, a major challenge. The present study proposes an oxyfuel NGCC integrated with Chemical looping (CL) syngas production (OXY-CC-CL), for power generation with CCS. The chemical looping CO2/H2O dissociation would produce syngas (CO and H2 with methane reduction step in redox cycle) from recycled exhaust gas for additional power generation within the power plant. This integration of CL unit with the existing conventional oxy fuel power plant would be expected to decrease the efficiency penalty. Therefore, the thermodynamic (both energetic and exergetic), economic and environmental performance of the integrated chemical looping unit oxyfuel NGCC power plant with carbon capture were assessed. A 500 MW scale plant was modelled and compared with a conventional NGCC and oxyfuel NGCC plant with carbon capture (OXY-CC). The net efficiency penalty of the proposed OXY-CC-CL unit was 4.2% compared to an efficiency penalty of 11.8% of the OXY-CC unit with a 100% carbon capture. The energetic efficiency obtained hence was 50.7%, together with an exergetic efficiency of 47.1%. Heat integration via pinch analysis revealed the possibility to increase the system energetic efficiency up to 61%. Sensitivity analyses were performed to identify relative impacts of system operational parameters. The specific capital cost of the proposed OXY-CC-CL was obtained as 2455 $/kW, with a corresponding LCOE of 128 $/MWh without carbon credits.