Energy analysis of a solar-assisted ejector cycle air conditioning system with low temperature thermal energy storage

Thermal energy storage is essential in solar cooling applications due to intermittent and uncontrollable availability of solar energy. Various technologies are available for low temperature energy storage. In the present work, a solar-assisted ejector cooling system with latent heat cold storage and conventional auxiliary heating was considered. The latter was applied in order to assure constant operating conditions for the ejector cycle. The analysis was carried out for an office building with cooling requirements during working hours only. The capacity of the cold storage was selected to ensure full coverage of the cooling load throughout the periods with cooling requirements. A quantitative energy analysis is presented, assessing the influence of parameters such as rated system power, ejector energy efficiency, solar collector area, ejector operating conditions and the amount of energy from the auxiliary source. Two energy efficiency parameters were defined, based on which the optimum system configuration and operating principle were identified. The advantages of each configuration were described.

► Solar-driven air conditioning provides significant potential for energy savings.
► Thermal energy storage – key component of solar-driven refrigeration applications.
► Correct sizing of the energy storage unit requires system simulation.