Heat transfer enhancement of power-law fluid in a solar-driven pretreatment system for microalgae hydrothermal liquefaction

In this article, the flow and heat transfer performance of microalgae slurry in a solar-driven rectangular absorption tube with embedded vortex generators were studied by data optimization analysis and numerical simulation. The orthogonal test design method was used to establish an orthogonal test table by changing the shape, height, spacing, and fluid flow rate of the vortex generator to determine the optimal combination of various factors. Then the response surface analysis method was used for further optimization analysis. Eventually, the flow and heat transfer performance of microalgae slurry were studied numerically, and the optimal data were verified. The results show that the optimal comprehensive heat transfer performance (PEC) is delivered by the cylindrical vortex generator with height of 9 mm and spacing of 28 mm when the inlet velocity of microalgae slurry is 0.02 m/s. It can be seen that the data analysis method combined with numerical simulation can optimize the experimental process parameters and save the cost of the engineering design process, effectively and practically.