Performance of a novel cold thermal storage material in an emulated air conditioning system using different storage strategies.
Abstract With the increasing use of thermal energy storage in space cooling systems, various phase change materials have been explored. Semi-clathrate hydrates of quaternary ammonium salts can form under atmosphere pressure at applicable temperature ranges of air conditioning systems, among which tetrabutylammonium bromide (TBAB) hydrate has aroused most intensive interests in the past decade. This paper presents an experimental study to modify the phase equilibrium point of a novel TBAB hydrate based cold storage material, and investigates the material's performance in an emulate cold storage air conditioning system at various operation modes. Single charging and discharging operations, tank charging with chiller delivering load, and tank discharging with chiller delivering load operations with or without using bypass, are implemented to achieve full-storage and partial-storage strategies. The temperature distribution, charging and discharging rate and capacity are studied as key indexes to evaluate the cold storage performance. It was during a tank charging-chiller delivering load operation, using bypass is unfavourable for thermal storage effectiveness. During a tank discharging-chiller delivering load operation, chiller starting at a later stage with bypass is favourable for the system efficiency.