Development and Investigations on a Novel Solar Bubble Column Liquid Desiccant Regenerator

Energy used for cooling in buildings is poised to grow multifold in decades to come due to economic development and craving for high living standards in developing countries. Sustainable development in this area would need development and adoption of eco-friendly and energy efficient air-conditioning technologies. One such promising technology is liquid desiccant-based air conditioning (LDAC) system. Current work deals with development and investigation of a novel Solar Bubble Column Liquid Desiccant Regenerator (SBC_LDR) which is a part of LDAC system where energy in form of heat is supplied. SBC_LDR integrates the energy conversion (solar energy to thermal energy) and liquid desiccant (LD) regeneration (water removal from dilute LD) in a compact integrated system vis-à-vis conventional systems which use numerous components to achieve these functions. SBC_LDR adopts bubble column scheme, provides long residence time to bubbles and creates high turbulence in the LD pool, invigorating the heat and mass transfer processes in the device; finally resulting in high energy efficiency. Three sets of experiments, each running 3–5 days have been conducted on SBC_LDR, increasing concentration from lower to higher working range (~35 to ~ 45%) of a liquid desiccant-based air-conditioning system using calcium chloride as LD. It is seen that high solar insolation, low concentration and high turbulence provided by air bubbles resulted in the highest energy efficiency of the system. Solar COP up to 0.66 could be achieved in the given setup which is higher than those reported in literature for single stage systems with low complexity.