Session: 08-09-01: Thermal Energy Storage

Paper Number: 99359

99359 - Thermal Analysis of a Latent Heat Thermal Energy Storage Unit Enhanced With Porous Annular Fins 

Transitioning the world from fossil fuels to renewable energy requires energy storage techniques that combat the intermittency issue associated with renewable energy harvesting. In applications such as concentrated solar power generation, the use of thermal energy storage is a promising option. Specifically, latent heat thermal energy storage (LHTES) systems, which utilize a phase change material (PCM) to store and release thermal energy via a heat transfer fluid (HTF). These systems are effective because they offer high energy storage density due to high latent heat of fusion of PCMs and nearly isothermal heat transfer during phase transition. Despite these qualities, PCMs performance is ultimately impeded by their typical low thermal conductivity. Therefore, passive heat transfer enhancement techniques are employed to increase heat transfer rate to and from the system. Common passive heat transfer enhancement techniques include nanoparticle dispersion, heat pipes, conductive porous matrices, and extended surfaces and fins within the PCM. The individual efficacy of conductive porous matrices and fins has been evaluated by many, but not the combination in the form of a conductive, porous fin. In the current study, annular porous copper fins are employed within a LHTES system housing Rubitherm RT 55 PCM. Two 10 annular porous fin configurations of 20 and 40 PPI are used. The porous fins are compared to an equivalent but solid configuration to determine the effect of the porous fins during the charging and discharging processes of the LHTES unit. The temperature of the PCM is monitored with 12 k-type thermocouples inserted at varying heights and depths of the PCM. Charging is considered complete when all the PCM is molten and the PCM temperature has plateaued. Discharging is considered complete when the temperature of the PCM has reached below 25 ºC throughout. Additionally, the inlet and outlet temperature of the HTF is measured by two RTDs. The difference between the inlet and outlet HTF temperature is used to evaluate the energy exchange of the system. Digital and thermal images track the melting and solidification of the PCM throughout the charging and discharging processes, respectively. The total charging and discharging times of the PCM, as well as the energy response, are used to determine the effectiveness of porous annular fins compared to solid fins. The charging times of the solid, 40 PPI, and 20 PPI fins are 7.67, 13.23, and 19.06 hours, respectively. The discharging times of the solid, 40 PPI, and 20 PPI fins are 14.44, 20.98, and 21.1 hours, respectively.

 

Presenting Author: Saeed Tiari Gannon University

Presenting Author Biography: Dr. Saeed Tiari is an Associate Professor in the Department of Biomedical, Industrial and Systems Engineering at Gannon University. Prior to joining Gannon University in 2016, Dr. Tiari obtained his Ph.D. in Mechanical Engineering from Temple University. His main research interests include bioheat transfer, biofluid mechanics, multiphase flow and heat transfer and thermal energy storage systems. Dr. Tiari received his M.S. in Biomedical Engineering from Amirkabir University of Technology (Tehran Polytechnic) in 2012. He also received his Mechanical Engineering undergraduate degree from the University of Tehran in Iran.

Authors:

Kyle Shank Gannon University
Jessica Bernat Gannon University
Ethan Regal Gannon University
Shiva Pandiri Gannon University
Saeed Tiari Gannon University