Evaluating the Performance of a Combined SHS-LHS System

In the present work, a combined sensible heat storage-latent heat storage (SHS-LHS) system has been evaluated with Aragonite, which belongs to the category of Limestone, as the sensible heat storage material and Potassium Hydroxide (KOH) as the latent heat storage material. The performance of the combined sensible-latent heat storage system is analyzed and compared with a sensible only heat storage system by evaluating key parameters such as Heat Transfer Fluid (HTF) exit temperature, average temperature of the heat storage system and the amount of energy stored and retrieved during charging and discharging respectively. It was found that a combined sensible-latent heat storage system stabilizes the HTF exit temperature to around the temperature of the phase change material (PCM) during the discharge cycle. This has also been corroborated by other researchers in their experimental work. It was also found for both the systems (sensible and combined) that the larger the pellet diameter, the longer is the time taken by the Thermal Energy Storage System (TESS) to reach the maximum operating temperature. For both the systems, the temperatures remain at the maximum operating temperature for a longer duration at lower HTF flow rates. This helps in maintaining the stability of the temperatures in a TESS for a longer duration, which in turn, to a limited extent, offsets the losses caused due to a rapid reduction in the outlet temperature in a sensible TESS. The amount of energy retrieved from the combined system is larger than the energy that is retrieved from a sensible only TESS. All these findings point to the fact that using a combined sensible-latent TESS is highly advantageous as compared to a sensible only TESS.