An evacuated tube solar bubble column liquid desiccant regenerator

Abstract

Liquid desiccant air conditioners (LDAC) are environmentally friendly, require less energy, and can improve air quality. These systems are composed of two main parts: a dehumidifier and a regenerator which are heat and mass exchanger devices that are the main bottlenecks on the overall performance of LDAC systems. Despite their numerous advantages over conventional regenerators, bubble column regenerators have only been studied adiabatically. To address this gap in the literature, an internally heated bubble column regenerator is proposed that is heated with an evacuated tube solar collector while also eliminating the previous issues with corrosion. A prototype was constructed, and the effect of various values of air flow rate, air injection depth, and initial desiccant concentration was studied experimentally in 10 cases (8 modified cases, 2 conventional cases). The results showed that initial concentration has the highest impact on the device’s performance. Increasing air flow rate led to higher water extraction. Air injection depth had no significant impact on the device’s output. In Case 10 (10 L/min air flow rate, 50 cm hose depth, and 30 % initial desiccant concentration), a maximum of 576 g of water was removed from the desiccant. The maximum improvement over the conventional case was 139 % which was achieved in Case 5 (10 L/min air flow rate, 50 cm hose depth, and 35 % initial desiccant concentration). The exergy efficiency for Case 10 was the highest, reaching 8.5 % at the end of the experiment.