| Thermal storage system has been used widely in the world, since it can shifts the on-peak electricity load to off-peak time and balance the power grids. For lager air-conditioning systems, the promise of money savings with thermal storage system is encouraging. The principle of heat exchange inside the stratified thermal storage tank was analyzed in this paper, and a one-dimensional, implicit, finite-difference model of a single stratified thermal storage tank has been developed. Turbulent mixing was included with conduction by introducing a mixing factor EDDY. The model covers the experiment with variable flow rates and temperature difference for charging or discharging the thermal storage tank for two type inlet configurations. A computer program was developed to simulate the temperature profile of a stratified storage tank. The result show that a very simple one-dimensional numerical model can accurately simulated a stratified chilled-water thermal storage tank.By adjusting the mixing factor EDDY in the simulation computer program, simulated the temperature profile inside the tank, and compared it to the experiment data, then found out the turbulent mixing character inside the tank. It showed that the mixing factor EDDY decreased from a maximum value at the inlet to a minimum value at the outlet; the decreasing exponential function predicted the best variation of the EDDY inside the tank. A general relationship between EDDY inlet and the Reynolds/Richardson number was found for the two type inlets investigated.In the finally, the relationship between EDDY and the inlet configurations was discussed. The result showed that the mixing factor EDDY inside the tank of the two type inlets have the same variations style. But compared to the octagonal inlet diffuser, the radial disk inlet diffuser has a small mixing factor EDDY and high energy efficiency. |
