Cooling and heating with clathrate thermal energy storage system

Closed-loop cooling and heating cycles utilizing clathrate as the storage medium are developed to verify the system's technical operation and to evaluate system components. In addition, a macroscopic study of the clathrate solidification process is made.; The constructed experimental cycle can be reversed between cooling and heating utilizing the same thermal energy storage (TES) system. The system is developed to operate with clathrates having low and high phase change temperatures, since there is a great potential for these groups of gaseous clathrates to be discovered in the near future.; Test runs (for cooling and heating) were performed utilizing basic Refrigerant clathrate as the storage medium. Both the cooling and heating cycles operated with direct contact heat transfer between the refrigerant and water or clathrate. R-12 clathrate was selected solely due to its low cost and easy accessibility.; Experimental data were collected via implementation of a Dash-8-IBM PC data acquisition system. Crystallizer temperature and pressure variations with respect to time during system energy charging, energy storage, and energy recovery were plotted for a number of runs. Computer codes were developed to perform energy balances for each system component for both the cooling and heating cycles.; Clathrate formation temperatures as high as 47 F and as low as 39 F resulted for the cooling test runs with agitation being essential to minimize subcooling. In the case of the heating cycle, the solidification temperature increased to about 53 F for some runs. The gas hydrate solidification process was studied during storage medium cool down by a freezing coil. No clathrate was detected to be accumulating on or near the coil for any of the test runs. The entire solidification process took place at the gaseous refrigerant/water and liquid refrigerant/water interfaces. Absence of clathrate formation or accumulation around the coil is important, for the phenomenon increases the system thermodynamic performance. Results of the experimental tests reveal successful operation of the cooling and heating cycles utilizing a common thermal energy storage system. The results also indicate that the system can evaluate other groups of clathrates in simulated cycles for both cooling and heating.