Effect of inlet flow maldistribution on performance of plate fin heat exchanger coupled with hydrogen ortho-para catalytic conversion

The plate fin heat exchanger coupled with hydrogen ortho-para catalytic conversion (PFHE-OP) is a key equipment for the integration of flow heat transfer and catalytic conversion in hydrogen liquefaction systems, and inlet flow maldistribution is one of the key factors affecting its performance. A distributed parameter model of multi-stream PFHE-OP was constructed in this research, and the effects of inlet flow maldistribution parameter ϕ of fluids A, B, and C on the flow and heat transfer characteristics, as well as the efficiency of o-p in PFHE-OP, were investigated; where A was the hot fluid hydrogen involving in op, and B was the hot fluid helium, and C was the cold fluid helium. The results indicated that when ϕ_A, ϕ_B and ϕ_C increased from 0 to 1.5, the heat exchange amount decreased by 3.3%, 8.8%, and 10.0%, respectively; ϕ_C had the most significant effect on the heat transfer amount, because fluid C, being hot fluid, had a larger mass flowrate than the sum of the mass flowrate of cold fluid A and B. The pump power increased with the increase of ϕ_A, decreased with the increase of ϕB, and first decreased and then increased with the increase of ϕ_C, and the heat exchange amount per unit pump power (HEPUP) gradually decreased with the increase of ϕ_A, ϕ_B and ϕ_C; the pump power and HEPUP were most sensitive to ϕ_A, which was due to that fluid A channel was filled with catalyst. Although no o-p was involved in fluid C, the influence of ϕ_C on the distribution of the para-hydrogen mass fraction at the outlet of fluid A was the most significant; with ϕ_C increasing from 0 to 1.5, the outlet para-hydrogen mass fraction in fluid channels near the top and the bottom decreased up to 11.9%; the increase in ϕ_C limits the o-p rate in the channels of fluid A near the top and bottom. The results can provide theoretical guidance for the optimization design of multi-stream PFHE-OP and promote the efficient utilization of hydrogen energy.