Design and performance simulation of the spiral mini-channel reactor during H2 absorption

• A SMCR is proposed to eliminate thermal stress and improve heat transfer efficiency.
• The structure parameters of SMCR are optimized as ra = 2.2 mm, b = 5 mm, and rc = 5.5 mm.
• The operating conditions are optimized to increase efficiency during H2 absorption.
• The elliptical tube can replace circular tube in SMCR which has better performances.

The metal hydrides have great potential for the storage and utilization of hydrogen. Because of the strong exothermic/endothermic effect of H2 absorption/desorption process, the structure development of metal hydride reactor should mainly focus on the heat transfer enhancement. The new spiral mini-channel reactor is proposed to increase the heat transfer efficiency and H2 absorption rate. The spiral tubes can not only eliminate the stress produced by temperature changes and volumetric expansions, but also improve the turbulent intensity and heat transfer rate. The numerical model of spiral mini-channel reactor is established, and the simulation results present that the new reactor shows high thermal efficiency and hydrogenation rate. The structure parameters of the reactor are optimized as minor radius of 2.2 mm, axial pitch of 5 mm, major radius of 5.5 mm and tube amount of 3. Furthermore, the operation conditions are investigated. The result indicates that superior performance is obtained for the packing fraction of 0.6 and H2 pressure over 10 atm during H2 absorption. With these promising features, this new spiral mini-channel reactor has broad prospects in the hydrogen energy field.