Investigation of an improved solar-powered open absorption system for cooling, dehumidification and air conditioning

This study is concerned with an open absorption (liquid desiccant) system, capable of producing both cooling and dehumidification for air conditioning, utilizing low-grade heat. The system includes a novel solution heat and mass exchanger (HME) designed to serve as a desiccant solution reservoir for both the absorber and desorber, enabling mass transfer between them with minimum heat transfer losses and eliminating the need for an external recuperative heat exchanger. The use of this new HME together with an improved solution flow arrangement in the new system facilitates the use of adiabatic absorption/desorption with minimum circulation heat losses and wetting problems. The characteristic performance of the system was studied under varying operating conditions. The use of the new HME has fulfilled the objective of reducing the time constant of the system, helped correct idling and level control problems and ensures maximum solution concentration on the absorber side during desorber operation.

► A 20 kW laboratory liquid desiccant system, powered by solar energy, was constructed and tested.
► Novel heat and mass exchanger (HME) incorporated in the system improved performance.
► COP values around 0.8 obtained consistently with solar heated water to 65 °C.
► Humidity of ambient air processed through the system reduced approximately to 60% of its original value.