Experiment study and heat resistance analysis on heat transfer characteristics in staggered tube moving bed heat exchangers

Heat transfer of high temperature granules in the moving bed heat exchanger is an important thermal process in a blast furnace slag waste heat recovery system. Gaining a comprehensive understanding of granular side heat transfer characteristics is crucial. Here, we experimentally investigated the effects of velocity, diameter, diameter distribution, inlet temperature and granule type on granular side heat transfer and the development of heat transfer in the flow direction in a staggered tube array. Furthermore, the experimental results were analysed via the thermal resistance theory. The obtained results indicate that the heat transfer coefficient increases with increasing velocity and inlet temperature and decreases with increasing diameter. Multi-sized granules and blast furnace slag have better heat transfer than mono-sized granules and phosphorus slag, respectively. The heat transfer coefficient tends to increase and then decrease in the flow direction, with the location of the peak, depending on the ratio of the contact and penetration thermal resistance. The semi-empirical formula based on experimental results can provide a theoretical basis required to design.