Numerical investigation of metal hydride heat storage reactor with two types multiple heat transfer tubes structures

Abstract

Metal hydride, as one of the potential materials, has a substantial thermal effect on the reaction, which can degrade reactor efficiency if heat is not transmitted effectively. In this research article, two types multiple heat transfer tubes (MHTT) reactors with center tube (CT) and no central tube (NCT) are proposed to enhance radial heat transfer. The three-dimensional thermal coupling model between MHTT and bed is established. It is found that the most uniform heat and mass transfer effects occur when the position ratios of CT and NCT are 0.62 and 0.56, respectively. The heat transfer mechanism analysis reveals that the CT and NCT operate on the basis of the processes of formation, diffusion, and fusion of multiple reaction fronts, as well as the movement of a new reaction front. According to the optimization calculation, the best performance of the CT and NCT is achieved when the number of tubes in the CT and NCT is 7 and 3, respectively. CT has better performance as compared to NCT. In particular, gravimetric exergy-output power of reactor (GEOPR) increases from 10.22 W kg−1 to 61.41 W kg−1. Furthermore, it has been demonstrated that the performance of CT is superior to the other structures.