Effect of regeneration mode on the performance of liquid desiccant packed bed regenerator

The regenerator is one of the key components in liquid desiccant air-conditioning systems, in which desiccant is concentrated and can be reused in the system. The regeneration heat is supplied into the regenerator by either hot air or hot desiccant. The heat and mass transfer performances of these two regeneration modes are analyzed and compared in detail. In the hot air driven regenerator, the parallel-flow regenerator has the best mass transfer performance and the counter-flow performs poorest under the same conditions, because the heat transfer process is the governing process and the mass transfer performance depends on the promotion of the heat transfer to the mass transfer process. In the hot desiccant driven regenerator, counter-flow configuration has the best mass transfer performance and parallel-flow is the poorest at the same conditions, since mass transfer is the governing process. Regeneration heat should be chosen to heat the desiccant instead of the air in the packed bed regenerator, since the hot desiccant driven regenerator has apparent better mass transfer performance. The proposed regeneration mode and flow pattern will be helpful in the design and optimization of the regenerators.