Capacitive deionization regeneration as a possible improvement of membrane regeneration method for absorption air-conditioning system

Abstract

Driven by renewable energy and being environment friendly, the absorption air-conditioning system is a good choice for green buildings. Concentrating the absorbent solution with electrodialysis method, the membrane regeneration absorption system has higher performance than the traditional absorption system. Its theoretical coefficient of performance can approach 6 under certain working conditions. However, the experimental data in this paper reveals the actual coefficient of performance of the membrane regeneration system is about 1–2, much lower than expected. It is caused by the energy loss in heating and electrochemical reactions. To improve, a capacitive deionization regeneration method is proposed: strong absorbent solution and pure water are acquired with the joint work of two units. Analysis has been made on the absorption air-conditioning system adopting this method. The mass and energy equations have been developed and some parameters have been investigated for performance optimization. Even with conservative prediction, the results show the capacitive deionization method has better performance than the membrane regeneration method. The coefficient of performance can be enhanced by 100% with the energy recovery strategy. Capacitive deionization method also has advantages on the cost and maintenance, which makes it a promising choice for the absorption air-conditioning system.