Session: 11-06-01 Heat Transfer in Solar and Renewable Energy Systems - Concentrated Solar Power and Thermal Storage

Paper Number: 73008

Start Time: Monday, 11:35 AM

73008 - Thermal Performance of a Packed Bed Latent Heat Thermal Energy Storage With Pure Silicon as PCM 

In this paper, effect of mass flow rate and inlet temperature on the thermal performance of a packed bed latent heat thermal energy storage has been numerically investigated. As the Heat Transfer Fluid (HTF), hot air is selected. Pure silicon is chosen as the PCM (Phase Change Material). The effects of HTF mass flow rate and HTF inlet temperature on the thermal performance have been numerically investigated. The thermal performance has been evaluated on the basis of the following parameters:  energy transfer efficiency (ƞ), TES heat storage capacity (Q_charging), TES charging rate (p), TES density (q), TES rate density (w). The values of these parameters have been calculated and compared for four different mass flow rates (0.08 Kg/s, 0.1 kg/s, 0.12 kg/s, 0.15 Kg/s) and four different inlet temperatures (1800K, 1900K, 2000K, 2100 K) of the heat transfer fluid. For each case of mass flow rate, the inlet temperature is kept fixed at 2000K and for each case of inlet temperature, the mass flow rate is kept fixed at 0.1 Kg/s. The charging time is 500 seconds for each case. The total PCM mass for each case is 5.08 kg. The results are obtained by running simulations for each case in ANSYS fluent. PCM melting is modelled by using solidification/melting model. The results show that after the end of charging time, 47.3% increase in the values of heat storage capacity, charging rate, TES density and TES rate density take place when HTF mass flow rate is increased from 0.08 kg/s to 0.15 kg/s. After the charging time, the values of heat storage capacity, charging rate, TES density and TES rate density increase up to 2.6 times when HTF inlet temperature is increased from 1800K to 2100K. The energy transfer efficiency does not show significant difference for different values of inlet temperatures but is slightly higher for lower values of mass flow rate. The average melt fraction after 500s is higher for higher mass flow rates and inlet temperatures of HTF. A 41.5% increase takes place in the final value of melt fraction (0.4364 to 0.6177) for raising the mass flow rate from 0.08 kg/s to 0.15 kg/s. The value of melt fraction after 500s more than triples (0.1819 to 0.6278) for increasing the value of inlet temperature from 1800K to 2100K. A conclusion can be drawn that the heat transfer fluid inlet temperature has more impact on the performance of packed bed latent heat thermal energy storage.

Presenting Author: Titan C. Paul University of South Carolina

Authors:

Sumit Saha Bangladesh University of Engineering and Technology
Abu Raj Md. Ruslan Bangladesh University of Engineering and Technology
A. K. M. M. Morshed Bangladesh University of Engineering and Technology
Titan C. Paul University of South Carolina