Structural improvement of catalyst filled channel of continuous ortho-para hydrogen conversion technology

The continuous ortho–para hydrogen conversion (OPHC) technology is a novel and effective method for solving the OPHC challenge in hydrogen liquefaction, whose key application is the catalyst filled plate-fin heat exchanger (CFPFHE). However, the incoordination of the OPHC and heat transfer greatly limits the overall performances of the CFPFHE. To solve it, this paper attempts various catalyst filled channels to improve the overall performances of the CFPFHE by numerical simulation. Firstly, for the perforated fin channel, the special perforated structure makes its overall performances slightly better than the plain fin channel. Secondly, considering the excellent heat transfer of the catalyst filled channel and the demand increasing the catalyst filled amount, the plate channel is proposed by removing the fins between the plates. The results indicate that the surface heat transfer coefficient α_h of the plate channel matches well with the serrated fin channel of the cold side. Compared with the plain fin channel, the pressure drop Δp of the plate channel is decreased by 25.12%–27.89%, and the OPHC index YY_pH2 is increased by 2.62%–4.50%. From the perspective of YY_pH2 ≥ 95%, the allowable working condition of the plate channel is more than 3 times that of the plain fin channel. Meanwhile, the plate channel with a large plate spacing d_h sacrifices a part of α_h, but it greatly improves the flow performance and OPHC performance. Further, the performance correlations of the plate channel are obtained to facilitate the design of the plate channel in the CFPFHE.