Performance of heat pump driven internally cooled liquid desiccant dehumidification system

Internally cooled liquid desiccant dehumidification systems are considered to be compact and efficient dehumidification systems in the air-conditioning field. A theoretical method is proposed to investigate the ideal maximum coefficient of performance and current gaps between actual and ideal working conditions of the heat pump driven internally cooled liquid desiccant dehumidification system. It is found that the maximum coefficient of performance is determined by the inlet humidity ratio of process air and regeneration air, and the required humidity ratio difference. It has been proved to be not significantly affected by the solution concentration. Furthermore, three perfectness are identified and deduced to explain gaps between the actual and ideal working condition. They include heat-cold offset perfectness due to heat-cold offset of the circulating solution between dehumidifier and regenerator, transfer capacity perfectness due to the limited transfer capacity of the internally cooled/heated dehumidifier/regenerator, and heat pump thermodynamic perfectness. The results indicate that actual coefficient of performance generally only corresponds to 10%-35% of the maximum coefficient of performance. With aid of the aforementioned perfectness, reasons for limited coefficient of performance of the current system are analyzed to illustrate future improvement direction and potential.