Numerical investigation on flow and heat transfer processes of novel methanol cracking device for internal combustion engine exhaust heat recovery

In this research, a novel structure of methanol cracking device was designed for methanol decomposition by using internal combustion (IC) engine exhaust heat. To evaluate and optimize its performance, the flow and heat transfer processes in methanol cracking device were investigated by computational fluid dynamics (CFD) simulation. The results show that methanol flow rate has important effects on the pressure loss, temperature distribution and heat flux. In general, the flow velocity and pressure in methanol cracking device are not well-proportioned and it results in the asymmetrical distributions of temperature and heat transfer coefficient. The maximum heat transfer coefficient is close to 100 W/(m2·K) while the minimum almost equals to zero because of flow stagnant zone. The average heat transfer coefficient increases as methanol flow rate rises, and it reaches to 51.63 W/(m2·K) at the methanol flow rate of 0.06 kg/s. When methanol flow rate increases from 0.03 kg/s to 0.06 kg/s, the average outlet temperature decreases from 615 K to 560 K and meets the requirements for methanol cracking reaction. All these indicate that the designed methanol cracking device can be used for IC engine exhaust heat cracking methanol, and also provide theoretical guidance for further optimizing the geometry structure.