An experimental study on the performance evaluation of a combined sensible‐latent heat thermal energy storage

Abstract

SummaryThermal energy storage (TES) is one of the significant technologies for reducing the discrepancy between ever‐increasing energy demand and utilization. Sensible and latent heat based TES concepts are the most widely implemented technologies for thermal applications. However, these two storage technologies have drawbacks of lower energy storage ability, higher thermocline degradation for sensible heat storage and lower thermal conductivity of the phase change material (PCM) causing higher charge and discharge times for latent heat storage. To counter these issues, a novel combined sensible‐latent heat storage system has been proposed. The concept of combined sensible‐latent thermal storage is to place the latent heat storage media above the sensible storage media in the storage container. In the present experimental study, an experimental investigation of the proposed storage system and conventional sensible storage system was performed during charge and discharge cycles. The proposed storage system used concrete spheres as sensible storage media and paraffin encapsulated capsules having the same diameter of 38 mm, as a latent heat storage media. A comparative assessment has been made for two different configurations based on temperature profile, storage capacity, charge and discharge times, energy transferred, and energy recovered. The experimental results reveal that the novel combined sensible‐latent heat storage has lower thermocline degradation during discharge and higher energy storage capacity relative to the sensible storage system. The discharge time and energy utilization is prolonged by adding the PCM capsules above the concrete spheres and also the temperature drop at outlet of the storage system has been reduced than the sensible storage. Based on the analysis, the novel combined sensible‐latent heat storage was found to have a better performance compared with the conventional sensible heat storage system.

Molten salts: Potential candidates for thermal energy storage applications

“…The mass flow rate at the hot storage tank is controlled based on the electricity demand, and the salt is pumped to the intermediate heat exchanger to heat steam for driving the turbine. Then the salt is sent to a pre‐heater (to pre‐heat the condensed water from the turbine) and off to the cold storage tank 130 . The major issue with this design is the salt freezing when the primary heat source is lost.…”

“…Then the salt is sent to a pre-heater (to pre-heat the condensed water from the turbine) and off to the cold storage tank. 130 The major issue with this design is the salt freezing when the primary heat source is lost. The 19.9 MWe Gemasolar CSP plant (Spain) employs the two-tank direct ESS (with 120 MWt molten salt as the storage material).…”

Performance assessment of a phase change charging mode in a vertical thermal energy storage system

“…They found that the charging time of the latent heat system is superior to the sensible system by about 10.7%. In another research work carried out by Suresh and Saini, 14 they compared the performance of a combined TES system with a traditional sensible storage system that contains only concrete spheres as a packing element, and they concluded that better performance with their new system is obtained. On the other hand, Christopher et al 15 investigated the performance of TES combined with evacuated tube collectors.…”

Thermal performance of an accumulator unit using phase change material with a fixed volume of fins

“…It is a more energy‐efficient method than conventional accumulation 8 . The utilization of the PCM has been found to be useful for different applications including thermal management in building, 9‐11 performance enhancement in solar collectors, 12,13 and thermal energy storage 14,15 . There is an increasing research interest in using nanoparticles and fins for enhancing the thermal performance of the heat storage units 16‐19 …”