Design of monolith-typed reactor for vehicular hydrogen production

Abstract

This thesis studied the development of a small scale multifunctional reactor for hydrogen production for on-board fuel cell. The study was divided into three parts as follows: i) the comparison between the flow arrangements of the thermally coupled micro reformer (TMR) ii) the effect of the flow arrangement on the micro membrane reformer (MMR) performance and iii) design of thermally coupled monolithic membrane reformer (TMMR) for vehicle. In the case of TMR and MMR, both reformers were examined by three dimensional computational fluid dynamic simulation using COMSOL Multiphysics®. Parallel arrangement and checked arrangement were considered as the flow arrangement of the reformers. The checked arrangement in TMR reduced temperature difference between cold and hot spots due to higher heat transfer. As a result, the checked arrangement is appropriate for large channel width reformer. Since the checked arrangement has larger contact area, total membrane area was utilized in MMR. Higher hydrogen permeation and lower hydrogen accumulation were observed. The parameters’ influence in TMR and MMR was reported. According to the higher performance of the checked arrangement, the arrangement was employed in the TMMR design based on a commercial monolith configuration. The TMMR was designed using Gibbs reactor and Plug flow reactor models via Aspen Plus. The efficient condition was at 4 atm and methane of 0.30 mol/s for steam reforming and 0.03 mol/s for combustion. It was found that the energy efficiency of TMMR depended on exchange area of monolith. At optimal configuration (1.5 m2 of exchange area), 200 cpsi monolith and 150 mm of diameter and length produced hydrogen equivalent to 129 kW with 43.96% efficiency. Therefore, TMMR which has 2.65 liters of volume is a potential reformer for on-board hydrogen production.