Study on heat and mass transfer symmetry characteristic of metal hydride thermal compressor during absorption/desorption process

Research and optimization were conducted on heat and mass transfer symmetry of metal hydride thermal compressor (MHTC) between absorption/desorption during the operation of MHTC. On the basis of the local thermal equilibrium model, numerical simulation was performed on a domain with 2D annulus in multi-tube MHTC reactors, and the parameters of the simulation process and structure were also optimized. The results show that for the 4-layer multi-tube reactor, it expends 350 s for the reaction fraction to increase from 0.10 to 0.90 during absorption and 360 s to drop from 0.90 to 0.10 during desorption when the hydrogen pressure, temperature, and heat transfer coefficient are 2/0.05 MPa (absorption/desorption), 293/393 K, 1000 W·m^-2·K^-1, respectively. The largest temperature differences are 40 K and 43 K, respectively, showing a clear asymmetry between absorption/desorption. The equilibrium pressure inside the multi-tube reactor changes significantly and more than 50% of its total variation occurs in the first 20 s during desorption.