Comprehensive strategies for performance improvement of adsorption air conditioning systems: A review

Adsorption chiller technology has received much attention in the last few decades due to its advantages in utilizing low grade thermal energy and eco-friendly refrigerant. However, it has not been wide commercialized due to its low coefficient of performance (COP) and low specific cooling power (SCP) compared to conventional refrigeration technologies. This paper reviews different strategies to improve the COP and SCP of adsorption chillers. Heat recovery, mass recovery, multi-stage, multi-bed, improved adsorption structures and optimized operating conditions are discussed in this review. This study revealed that: (i) for operating conditions of low evaporative temperature, low generation temperature or high condensing temperature, a mass recovery technique is strongly recommended; (ii) in the case of intermittent cold production systems, use of constant temperature adsorption cooling cycle strategy is preferred; (iii) an appropriate cycle time and switching time are important to achieve the optimal system performance since the adsorption chiller performance is strongly dependent on the operating conditions; (iv) by employing a novel composite adsorbent material, along with improvements in heat exchanger design, advanced adsorption cycles can be a promising technology to improve adsorption chiller performance. This review highlights the need for further research to reduce chiller manufacture costs, increase power-to-mass ratio and improve understanding of dynamic long term chiller performance when driven by solar or waste thermal energy.