Experimental and numerical investigation of cold thermal energy storage systems

In this thesis study, two different types of latent heat thermal energy storage (LHTES) systems are designed and fabricated to investigate the solidification and melting periods of water.In the shell?and?tube type LHTES system, natural convection dominated phase change process is investigated. An electronic interface measurement method is developed to monitor the solid?liquid interface variations during the phase change. Experimental results indicate that the mean relative difference of the current method is nearly ±3%, in comparison with the photography method. Results designate that, natural convection becomes the dominant heat transfer mechanism after a short heat conduction dominated period. Furthermore, parametric results indicate that the inlet temperature of the heat transfer fluid (HTF) is the most deterministic parameter on the stored and rejected energies. Besides, the natural convection dominated phase change is analyzed in a two?dimensional domain with the aid of FLUENT software. Comparisons are performed in terms of the time wise variations of interface positions and the mean deviation is obtained less than 2 mm.In the ice-on-coil type LHTES system, four different control strategies are tested to achieve a constant temperature value of the HTF at the inlet section of the tank. More stable inlet temperature of the HTF is achieved for the control with the HTF temperature at the outlet section of the evaporator. Parametric results emphasize that, for the current experimental conditions external melting mode can provide relatively lower outlet temperatures for a longer period. On the other hand, parametric energy and exergy analyses are carried out for the charging period of the system with using the thermal resistance network technique. Time wise variations of the total stored energy, mass of ice and outlet temperature of the HTF are compared with the experimental data. The mean deviation is obtained less than 4% in terms of the total mass of ice. After validation, performance of the system is investigated for several working and design parameters.