Reliability-based design optimization of screw shaft for continuous high-pressure hydrothermal co-liquefaction process

Abstract

Hydrothermal co-liquefaction (HTCL) is the prominent process for producing bio-products with a higher conversion rate. It is performed at high temperatures and pressure in the presence of water. Earlier, it was mostly conducted in batch reactors, but it has major limitations including operating volume, back mixing, and tedious process for high productivity. With that, the present investigation is performed on designing the screw shaft for the high-pressure HTCL process. The dimensional factors including flight length, pitch, helix angle, and depth were considered to design the optimal screw shaft. Likewise, principal stresses, shear stress, bending stress, bending moment, and total deformation were regarded as inevitable response variables to analyze the internal strength of the shaft. In this regard, the Taguchi approach provides the L9 (34) orthogonal array as an experimental design. Then, the numerical results from the transient structural analysis were analyzed with the assistance of statistical methods such as Grey Relational Grade (GRG), Grey Fuzzy Reasoning Grade, Analysis of Variance (ANOVA), and Taguchi method to find the most influential dimensions for minimizing the response variable. Consequently, the results from both GRG and Taguchi optimization were compared, and selected the most optimum parameters.

Keywords

• hydrothermal co-liquefaction
• screw shaft
• finite element method
• stress analysis
• goodman failure criteria
• multi and single response optimization technique