Design and performance optimization of diesel engine waste heat recovery methanol reforming hydrogen generation system

Abstract

A shell-and-tube Methanol Steam Reformer (MSR) system was designed for diesel engines. The effects of structural and operational parameters of the spiral baffles in the methanol reformer on heat transfer and hydrogen production performance were investigated. Additionally, a multi-objective optimization using response surface methodology was conducted to study the interactive effects of spacing and thickness, as well as liquid hourly space velocity and steam–methanol ratio, on the methanol conversion rate, hydrogen concentration and hydrogen production. The results indicated that reducing the baffle spacing and increasing the baffle thickness further improved heat transfer efficiency. Optimal conditions were achieved at a spacing of 30 mm and a thickness of 2 mm, resulting in a methanol conversion rate of 64.2 %. Increasing the steam–methanol ratio from 0.5 to 2 increased the methanol conversion rate from 50.6 % to 79.7 %, with a subsequent decrease in hydrogen concentration. Increasing the liquid hourly space velocity from 635 h−1 to 1905 h−1 significantly reduced the methanol conversion rate from 94.5 % to 64.2 %, but the hydrogen production increased from 0.111 mol/s to 0.228 mol/s. Optimization results indicate that the liquid hourly space velocity and steam–methanol ratio have a greater influence on the hydrogen production efficiency of the methanol reformer.