Adsorption and desorption of silica gel circulating fluidized beds for air conditioning systems

Abstract This article investigates low-energy consumption silica gel circulating fluidized beds for the dehumidification of air conditioning systems. The system consists of an adsorption bed, a desorption bed, and two fans. The fans drive silica gel particles upward to form fluidized beds; as the particles descend, funnels inside the beds allow particles to move between beds through connecting pipes. The particles circulate between absorption and desorption beds to create a continuous operating dehumidification air conditioning system. To achieve a fluidized state, air velocities between 4.0 m/s and 6.0 m/s and regeneration temperatures between 40 °C and 60 °C, which simulate low-temperature waste heat or solar thermal conditions, were chosen for the study. Altering funnel heights and adding oblique baffles to the system allowed us investigate different adsorption/desorption performances. The results show that single-tube fluidized bed can increase adsorption/desorption performance by 20% and lower the pressure drop by about 30%, compared to the packed bed. The circulating fluidized bed system has the highest Energy Factor by 0.554 kg/kW h, and improve the packed bed system by 124% due to the absence of a motor and has the largest total adsorption rate. Increasing air velocities and regeneration temperatures cause adsorption/desorption performance to rise in circulating fluidized bed systems. A regeneration temperature of 60 °C has the highest total adsorption rate of 343 g/h. Compared to the other funnel heights, a 200 mm funnel height with an oblique baffle that increases circulatory effects improves the total adsorption rate by 14% to reach an adsorption rate of 230 g/h.