Performance analysis of a novel multi-module columnar packed bed reactor with salt hydrates for thermochemical heat storage

Abstract

The thermochemical heat storage based on salt hydrate has great advantages of high energy storage density and applicability to seasonal heat storage. In conventional packed-bed reactors, salt hydrates are often simply accumulated, and the air diffuses inside the pores. As a result, the salt hydrates are prone to agglomeration during the reaction, which will reduce the performance. To address these issues, this paper designs a multi-module columnar packed-bed reactor. The performance of top peripheral air intake and bottom central air intake schemes is numerically compared, and the effects of working parameters, structural parameters and physical parameters are analyzed. The results show that the bottom central air intake scheme has obvious advantages of uniform reaction rate, short reaction time and small resistance loss compared with the top peripheral air intake scheme. It is found that the reaction time is shortened by 46.6 % and the heat storage efficiency increases from 80.4 % to 83.8 % when the inlet air temperature increases from 75 to 95 °C. Besides, the reaction time decreases by 20.7 % as the inlet air velocity increased from 1 to 3 m/s and the optimal spacing of the hydrated salt modules is 0.3 cm. These results are promoting the development of thermochemical heat storage.