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A rotary screw pyro-oil reactor was designed for powdery biomass for a feeding capacity of 40 kg h −1 with a moisture content of <10%. The pyro-oil reactor temperature was maintained at 450-550 °C. The pyro-oil vapors produced were quickly drafted out of the reactor for quenching to yield 16-24 L h −1 from 40 kg h −1 of biomass feed. The flash-pyrolysis technique, which is capable of directly turning biomass into a liquid fuel, was used to produce liquid fuel (bio-oil). It was carried out at a pressure at 0.03 bar and at a medium temperature of about 550 °C. The flash-pyrolysis technique converts the entire biomass matter, excluding the ash. In this method the powdery biomass is converted into three components: bio-oil (the yield is typically 70% on an energy basis, a powdery biomass feed at a moisture content of 10%); pyrolysis gas (typical yield 14%) and char (typical yield 16%). The temperature of the fixed bed was adjusted in the experiment, but the other variables remained constant, such as the amount of feed, the pyrolysis time of the gas product, the reactor pressure and the bed height. A biomass particle size range of 1-3 mm and a biomass residence time of 20 s in the reactor resulted in optimal bio-oil production of 70%. This work demonstrated how precise pyrolysis mechanism processes and bio-oil yields can influence the maximal reaction temperature in the 450-550 °C range. The performance analysis reveals that the fixed bed reaction temperatures of biomass rapid pyrolysis give reliable control over the bio-oil reactor type and size. This paper provides an overview of the design and thermochemical liquefaction process used to convert powdered biomass to biofuel.

Summary For a proton exchange membrane fuel cell (PEMFC), the pressure uniformity of fluid in the stack is a significant factor influencing the cell performance. This study employs the multi‐objective genetic algorithm (MOGA) to optimize the pressure uniformity in a PEMFC stack by adjusting the geometric design of inlet and outlet flow channels. The flow channel geometry is divided into three parts or named factors: tube length, tapered tube length, and channel height. The target is to find the minimum pressure difference between the inlet and outlet flow channels and optimize the pressure uniformity in the stack. The Latin hypercube sampling (LHS) method is used to organize the simulations for the design of experiments (DoEs), and the genetic aggregation (GA) method is employed to generate the response surfaces of the three factors. The resultant response surfaces are utilized to analyze the effects of the three factors on two objective functions, namely, pressure uniformity and pressure drop. The analysis of variance (ANOVA) method is also used to evaluate the influences of the factors, and the results are consistent with those obtained by the response surface method. The results show that the channel height produces the greatest impact on pressure uniformity. An increase in channel height can improve the pressure uniformity and reduce the pressure drop between the inlet and outlet channels. The MOGA analysis determines the optimal geometric design where the maximized pressure uniformity is 0.97 and the minimized pressure drop is 31 kPa. The number of cells in the stack is also taken into consideration. It is found that the influence of the inlet/outlet channel geometry on pressure uniformity is more pronounced when the cell number increases. The results benefit the design of inlet/outlet flow channels and the improvement of pressure uniformity in a PEMFC stack.

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