Study of tetra-n-butylammonium bromide and tetrahydrofuran hydrate formation kinetics as a cold storage material for air conditioning system

In order to utilize hydrate slurry for cold storage in air-conditioning system, the experimental studies on the phase behavior and formation kinetics of tetra-n-butylammonium bromide (TBAB) semiclathrate hydrate, tetrahydrofuran (THF) hydrate and TBAB-THF mixture hydrate have been carried out. By changing the concentrations of TBAB (5-55 wt.%), the variations of phase change temperature, equilibrium temperature, sub-cooling driving force, nucleation rate and electrical conductivity measurements have been compared. The results have revealed that the TBAB solution with 40-45 wt.% may be a promising cold storage material for air conditioning system because of higher temperature phase change of about 11.2 °C and maximum amount of hydrate formed of about 99.8%. In the case of TBAB and THF mixture, which prepared at 0-5.37 mass ratios, the phase change temperature and kinetic parameters depend on the amounts of THF and TBAB into the solution. At the mass ratios higher than 1.0, the above mentioned parameters increase, so that the increase in the TBAB concentration helps to increase the phase change temperature and kinetic parameters.