Session: Research Posters

Paper Number: 166828

Experimental and Numerical Investigation of a Latent Heat Thermal Energy Storage (Lhtes) System 

This research presents an integrated experimental and numerical investigation of a Latent Heat Thermal Energy Storage (LHTES) system designed to capture cool energy at night and release it during the day, leading to reduction in both water usage and energy demand in industrial cooling applications. The setup uses a phase change material (PCM) enhanced by multiple heat pipes and fins to overcome the PCM’s naturally low thermal conductivity. While the system currently uses a small fan at the condensation section, its final goal is to rely on fully passive thermosyphon-assisted commercial units become widely available.

On the experimental side, the apparatus consists of a three-chamber design. The bottom chamber circulates hot water (the heat transfer fluid, or HTF) at controlled temperatures of 40 °C, 45 °C, or 50 °C. The middle chamber holds up to 19 cm of PCM (Microtek 32), layered in carefully to minimize voids. Eight copper heat pipes pass through the PCM, each equipped with fins in their top (condensation) section to improve heat dissipation, while twelve thermistors track temperatures at key points, including the HTF inlet/outlet, along the heat pipes, and at multiple PCM depths.

For numerical work, a finite volume model is set up in ANSYS Fluent, using an enthalpy-porosity formulation to handle the melting and solidification of the PCM. To simulate the heat pipe internals, the domain is split into vapor, wick, and wall regions, with User-Defined Functions (UDFs) specifying the phase-change processes, saturation temperature, and the thermal conductivity of solid vs. liquid PCM. Heat transfer from the HTF and to the air is approximated via two separate convection analyses, each delivering a boundary condition for the evaporator and condenser sections respectively.

The results show strong agreement between experiments and simulations, with less than a 10% discrepancy in total melt/solidify times for all three HTF temperature levels. Raising the HTF temperature from 40 °C to 50 °C cuts the PCM melting duration by about half, demonstrating the impact of a higher temperature difference. During solidification, around 90% of the PCM re-solidifies within approximately three-quarters of the total discharge period, while the remaining liquid lingers in peripheral regions. System efficiency analyses indicate roughly 18% efficiency during charging and around 48% during discharging, strongly influenced by ambient conditions and natural convection effects. Taken together, these findings confirm the viability of an LHTES design that could help industries in arid regions substantially reduce water and energy consumption for cooling needs.

Presenting Author: Mohammad Shahabadifarahani University of Oklahoma

Presenting Author Biography: Mohammad Shahabadifarahani
Ph.D. Candidate of Mechanical Engineering at University of Oklahoma
Expertise: Thermal energy storage system, Thermofluidic analysis, Multiphase systems, CFD simulations

Authors:

Mohammad Shahabadifarahani University of Oklahoma
Hamidreza Shabgrad University of Oklahoma