Study on desiccant solution control strategies for efficient liquid desiccant air conditioning system control performance

Abstract

Frequent change in ambient conditions requires precise control of the desiccant solution operating parameters to suit the required conditioned space load. Either of the two control strategies shall be adopted for this, which are the dehumidifier solution inlet temperature (DSIT) control strategy and the dehumidifier solution inlet mass flow rate (DSIM) control strategy. This article aims to study the efficient control strategy selection approach for a specific air conditioning application since it leads to energy savings as well as thermal comfort. Initially, the optimum desiccant mass flow rate will be found for the liquid desiccant air conditioning system at peak ambient conditions. And the effect of the control strategies on system performance has been analytically investigated at different ambient conditions. A significant reduction in the solution heat addition rate has been observed with both control strategies with the addition of an air-solution heat exchanger. It has also been seen that the required chiller load is nearly same with both control strategies but a little drop (3%–14.5% variation) was observed with the DSIT strategy at low ambient conditions. However, a considerable drop in solution pumping power due to the significant reduction in solution mass flow rate and its pressure drop with the DSIM strategy suggests that it is an energy-efficient control strategy.