Study On Heat Transfer Intensification And Performance Of Spiral Mini-Channel Metal Hydrides Reactor

Metal hydride reactor is an important tool for hydrogen storage and transportation,which has many advantages such as large hydrogen storage capacity,low pressure,and low energy consumption.Due to the reaction between hydride and hydrogen is an exothermic and endothermic process,the heat transfer rate inside the reactor is one of the key factors affecting the performance of hydrogen absorption and desorption.In this thesis,the spiral mini-channel reactor with good elasticity and temperature compensation were optimized.and a multi-element valued model was used to comprehensively evaluate various reactors.To further optimize the spiral pipe structure parameters,a round spiral mini-channel reactor model was established based on the heat balance equation,and the reactor was also produced.The spiral tube heat exchanger was studied through numerical simulations,and experimentally obtained the convective heat transfer coefficient equation of the spiral tube.Simulation results indicated the forced convection heat transfer between the fluid inside the spiral tube and the bed is the main heat transfer method for the reactor,and the sensitivity order of round spiral tube structure parameters is Dc>Dt>Pt.Additionally,the effect of increasing the unit fluid flow on the bed temperature tends to get smaller as the fluid flow extends.Numerical model equation was employed to conduct the influence of the spiral tube type on the heat transfer performance,and the results showed that the heat transfer performance order of different tube spiral tubes obeys: elliptical spiral tube> round spiral tube> square spiral tube.Based on this,a conjugate elliptical spiral mini-channel reactor(C-ESMR)was proposed.Compared with the elliptical spiral mini-channel reactor,the maximum axial temperature difference of the hydrogen absorption/desorption bed of C-ESMR could reduce by 5.1 K/5.6 K,respectively.The parameters and operating conditions of the reactor were optimized.The results indicated that optimal installation parameters of the conjugate elliptical spiral tube is 180°,and the sensitivity of structure parameters order is Dc>A>B>Pt>?.The optimal hydrogen absorption/ desorption pressure is 0.8 MPa/0.1 MPa for continuous hydrogen absorption-desorption cycle process,and both reducing the hydrogen absorption temperature and increasing the hydrogen desorption temperature can reduce the cycle time effectively.Finally,a multi-element valued model was used to evaluate the reactor schemes comprehensively,and C-ESMR behaved an integrated superiority of 0.8816,confirming its superior to other reactors which would perform the high hydrogen storage efficiency and significant research prospect.